using the e7495a-b to make transmitter measurements

Agilent E7495A/B Base Station Test Set How to use the E7495A/B to Make Measurements – Lab Exercises

Agilent E7495A/B Base Station Test Set Lab Exercises 2

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What You’ll Find in this Document

Topic Page1. Perform Insertion Loss measurements on a cable and an attenuator

6

2. Perform Return Loss and Distance To Fault measurements on an antenna and its feedline

10

3. Make spectrum analyzer measurements 14

4. Perform channel scanner measurements on a GSM signal 17

5. Measure the average power of a GSM signal 20

6. Make CDMA transmitter measurements 24

7. Make “Over-the-Air” CDMA measurements 28

8. W- CDMA transmitter measurements in the code domain 33

9. W-CDMA (UMTS) Adjacent Channel Leakage Power Ratio (ACLR) Measurements

43

10. Perform T1 line measurements 47

Appendix A – Effects of Interference on Estimated Rho While Making CDMA Over Air Measurements

61

Appendix B – T1 Information 63


Introduction

Wireless network maintenance typically requires the use of many different tools. Wireless network technicians need an integrated, highly ruggedized and portable tool that is easy to use and provides sufficient capabilities to test, troubleshoot and maintain cell sites and the BTSs contained therein. The Agilent E7495A Base Station Test Set is the most comprehensive, full-featured test tool available for technicians� and RF engineers� day-to-day �in-the-field� test needs, and is capable of performing measurements on many wireless formats as will be demonstrated in the various lab exercises in this lab manual. In these lab exercises, you will perform many of the measurements required to sufficiently maintain wireless networks � specifically the base station cell site.

Lab Objective The student will become familiar with the operation and application of the E7495x BS Test Set.

Lab Outline This lab procedure is in 10 parts (chapters) each corresponding to a major functional area: • Chapter 1: Measuring insertion loss of a 10� cable and a 40dB attenuator (on page 6)

• Chapter 2: Measuring the return loss and distance to fault on an antenna and its feedline. (on page 10)

• Chapter 3: Performing spectrum analyzer measurements on a cdma2000 signal. (on page 14)

• Chapter 4: Performing channel scanner measurements on a GSM signal. (on page 17)

• Chapter 5: Measuring the average power of a GSM signal. (on page 20)

• Chapter 6: Performing CDMA2000 transmitter measurements. (on page 24)

• Chapter 7: Performing CDMA2000 over-the-air measurements. (on page 28)

• Chapter 8: Performing W-CDMA Transmitter Analysis in the code domain (on page 33)

• Chapter 9: Performing W-CDMA Adjacent Channel Power measurements (on page 43)

• Chapter 10: Performing T1 line measurements (optional) (on page 47)


The E7495A/B Base Station Test Set

Equipment Requirements The following equipment is required to conduct the E7495A/B Test Set labs: Quantity Description

1 E7495A or B Base Station Test Set (with all options: 200, 210, 220, 240, 600, 710) 2 10 dB Type N attenuators 1 40 dB Type N attenuator 2 2� Type N Jumper Cables *** 1 10� Type N Test Cable *** 2 Type N Female-Female connectors (Barrels) 1 8482A Power Sensor 1 Power Sensor Lead (for 8482A Power Sensors) 2 2� Type BNC Cables (for 10 MHz Reference and Even Second Reference

connections) 1 ESG-D Signal Generator (E4431B or higher � must generate 2 GHz signals) with

options UND (IS-95/cdma2000) , UN8 (TDMA formats) (Chapters 3-7) 1 ESG-D Signal Generator (E4438C) with option 400 (Chapters 8, 9 W-CDMA) 1 Electrodata T1-Lite test set (Chapter 10) E7495A/B with Option 710 required

*** If Type N Jumper and Test cables are not available, you may substitute the Type N cables with BNC cables and supply the necessary Type N � BNC adapters for each end of the cables.


1. Perform Insertion Loss measurements on a cable and an attenuator

Initially we will perform Insertion Loss measurements on the 10� test cable and a 40 dB attenuator that are provided with the test set. These measurements require calibration of the test set across the frequency range of interest. Insertion Loss measurements are important in accurately quantifying the amount of loss a signal will incur as it passes through a cable, attenuator, or any other device. In S-parameter terms Insertion Loss is referred to as an S21 measurement. �S� stands for scattering. In the instructions for this lab: Keystrokes surrounded by [ ] indicate hard keys located on the front panel of the test set, while keystrokes surrounded by { } indicate soft keys located on the left and/or right side of the display. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Turn on the test set [White Power Button] The test set defaults to the Mode menu. The following screen will appear.

Now turn the test set off by following the below instructions very carefully.


Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Turn off the test set Press the [White Power Button] for at least 5

seconds. Failure to press the button for less than 5 seconds causes the test set to go to Sleep mode.

Once the test set has completely shut down you can turn it back on. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Turn on the test set [White Power Button] 1.1 Select the desired frequency range and calibrate the test set for

Insertion Loss measurements. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select the Two Port Insertion Loss option {Antenna/Cable} {Two Port Insertion Loss} Set the Start Frequency to 800 MHz {Start Freq} [800] {MHz} Set the Stop Frequency to 950 MHz {Stop Freq} [950] {MHz} We are now ready to Normalize the test set over the 800-950 MHz frequency range. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select Normalize and follow the instructions of the Normalization Wizard

{Normalize}

Connect the 10 dB attenuators together in series and then connect them to the RF Out Port

Connect the 2� jumper cable to the RF In Port and then to the 10 dB attenuators connected to the RF Out Port

Select the Continue button {Continue} The test set is now Normalized across the desired frequency range. Note: Failure to Normalize the test set prior to making a measurement will most likely produce inaccurate measurement results. If you do not accurately quantify the loss incurred as a signal travels through a cable (or device) you likely use an inaccurate offset when performing power meter and other power related measurements. 1.2 Measure the Insertion Loss of the 10’ test cable Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set After the calibration is complete, disconnect the 10 dB attenuators and place the 10� test cable between the 10 dB attenuators (this will require the use of 1 of the Type N barrels)


Record the Average Insertion Loss of the 10� test cable:_________________________ 1.3 Measure the Insertion Loss of the 40 dB attenuator Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Replace the 10� test cable with the 40 dB attenuator.

Optional: If you prefer to have better resolution of the ripples in the Insertion Loss, you can change the reference level or use Autoscale to have the test set select the reference level and the scale per division for you. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Autoscale the signal to improve viewing {Level} {Autoscale} If desired, change the Reference Level and Scale per Division values

{Ref Level} [Appropriate Value] {dBm} {Scale/Div} [Appropriate Value] {dB}

Record the Average Insertion Loss of the 40 dB attenuator:_________________________ We need to store the insertion loss of the 40 dB attenuator for power meter measurements. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Store the loss of the 40 dB attenuator as the Power Meter Loss

{Store As} {Store As PM Loss}


Notice the value is written below the �PM Loss� button at the bottom of the right side of the screen. 1.4 Measure the Insertion Loss of the cable combined with the 40 dB attenuator Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Insert the 10� test cable along with the 40 dB attenuator. The order does not matter.

Record the Average Insertion Loss of the 10� test cable combined with the 40 dB attenuator:_________________________ We need to store this value in the test set for later use in making transmitter measurements in the cellular frequency band.

Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Store the loss of the 10� test cable/ 40 dB attenuator combination as the RF IN Loss and the RF OUT Loss

{Store As} {Store As RF IN Loss} {Store As RF OUT Loss}

Notice the value is written below the �RF IN Loss� and the �RF OUT Loss� buttons at the right side of the screen. The RF IN Loss value will be used as an offset when making base station transmitter measurements. The RF OUT Loss value will be used as an offset when making base station receiver measurements. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Disconnect the 2� jumper cable, 10� test cable, 40 dB attenuator and 10 dB attenuators from the test set.


2. Perform Return Loss and Distance To Fault measurements on an antenna and its feedline

We will perform a Return Loss measurement on an antenna and its feedline. If the Return Loss measurement is suspicious, we will perform a Distance To Fault measurement in an attempt to locate any fault or faults in the antenna feedline system. These measurements require calibration of the test set across the frequency range of interest. Return Loss measurements are beneficial in determining the integrity of an antenna feedline system. In S-parameter terms Return Loss is referred to as an S11 measurement. 2.1 Select the desired frequency range and calibrate the test set for Return Loss measurements. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select the Return Loss option [Mode] {Antenna/Cable} {Return Loss} Set the Start Frequency to 800 MHz {Start Freq} [800] {MHz} Set the Stop Frequency to 900 MHz {Stop Freq} [900] {MHz} We are now ready to calibrate the test set over the 800-900 MHz cellular frequency range. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select Calibration and follow the instructions of the Calibration Wizard

{Calibrate}

Connect the 2� jumper cable to the RF Out port and to the Open

Select the Continue button {Continue} Replace the Open with the Short Select the Continue button {Continue} Replace the Short with the 50 Ohm Load Select the Continue button {Continue} Remove the 50 Ohm Load The test set is now calibrated across the desired frequency range.

2.2 Measure the Return Loss Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Connect the 2� jumper cable to the antenna feedline and connect the antenna feedline to the antenna


Below the Return Loss display is a table displaying the frequency, return loss, and Standing Wave Ratio (SWR) of the Best and Worst return losses. These values may be changing rapidly. Let�s do a single sweep of the return loss measurement. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Perform a single sweep of the Return Loss measurement

{Average/Sweep} {Single}

For the Best Return Loss, record the Frequency:________________ Return Loss:______________ and SWR:___________ For the Worst Return Loss, record the Frequency:________________ Return Loss:______________ and SWR:___________ If the return loss value is suspiciously low (say less than 10 dB), you may want to perform a Distance To Fault measurement to determine if a noticeable fault exists and where it may be located. 2.3 Perform a Distance To Fault measurement Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select the Distance To Fault option [Mode] {Antenna/Cable} {Distance To Fault} Select the desired distance units Note: Don’t change the frequency range; frequency range is same as return loss measurement

{Units: Feet/Meters}

Set the distance of the antenna feedline to be measured

{Display Distance} [Enter Desired Distance]


Note: Typically the distance should be set 25% longer than the distance of the feedline Select the cable type Note: We will be using an RG-214 cable

{Cable Type: RG/BTS/Cust}

Select the RG-214 cable type {Select Cable} Using the RPG dial highlight “RG-214“. {Select}

We are now ready to calibrate the test set for the desired distance and selected cable type. Note: For Firmware rev. 1.6 and above a calibration is no longer required as long as using the same frequency as in return loss measurement. The calibration data is now saved and can be used in both return loss and distance to fault measurement. If using different frequency recalibration is required. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select Calibrate and follow the instructions of the Calibration Wizard

{Calibrate}

Disconnect from the antenna feedline and connect to the Open

Select the Continue button {Continue} Replace the Open with the Short Select the Continue button {Continue} Replace the Short with the 50 Ohm Load Select the Continue button {Continue} Remove the 50 Ohm Load The test set is now calibrated to make a Distance To Fault measurement.

Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Reconnect the 2� jumper cable to the antenna feedline


Notice that the worst 3 distances to fault and the associated return losses are displayed at the bottom of the screen.

For the worst 3 faults record the return loss and distance to that return loss. For the Worst Fault Return Loss:______________________ Distance:____________________ For the second Worst Fault Return Loss:___________________ Distance:__________________ For the third Worst Fault Return Loss:____________________ Distance:___________________ Does a fault exist in the antenna feedline? If so, at what distance? Looking at the trace, can you determine the distance of the antenna feedline? Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Disconnect the 2� jumper cable, the antenna feedline, and the antenna


3. Make spectrum analyzer measurements

We will view the spectrum of cdma2000 signal. We will also perform a channel scanner measurement on a GSM signal. The spectrum analyzer and channel scanner measurements do not require further calibration of the test set. We will use an ESG-D signal generator to provide the cdma2000 and GSM signals. We will analyze these signals using the spectrum analyzer and channel scanner capabilities of the E7495A. 3.1 Perform spectrum analyzer measurements on a cdma2000 signal Spectrum analyzer measurements provide valuable information on potential interfering signals as well as troubleshooting information concerning the base station transmitter. Configure the ESG-D to generate a cdma2000 signal at 1.955 GHz (Forward Channel 500). Instructions: ESG-D series signal generator Keystrokes: ESG-D series signal

generator Connect the 40 dB attenuator to the RF Output port of the ESG-D and then connect the 10� test cable to the 40 dB attenuator and to the RF In Port of the E7495A.

Turn on the signal generator [White Power Button] Set the center frequency to 1.955 GHz (PCS Band Forward Link Channel 500)

[Frequency] [1.955] {GHz}

Set the amplitude to �10 dBm [Amplitude] [+/-] [10] {dBm} Go to the cdma2000 mode under the built-in Arb Waveform Generator menu

[Mode] {Arb Waveform Generator} {CDMA Formats} {cdma2000 (Rev 8)}

Generate a 9-channel cdma2000 forward link signal

{Link: Forward/Reverse} {cdma2000: Off/On} [RF On/Off]

Configure the E7495A to analyze the cdma2000 Forward Channel 500 signal. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select the Spectrum Analyzer option [Mode] {Spectrum Analyzer/Tools}

{Spectrum Analyzer} Set the Units to Channels {Units: Freq/Chan} Set the channel to 500 Forward (1.955 GHz) {Channel} [500] {Fwd} Set the Span to 2 MHz {Span} [2] {MHz} Autoscale the signal {Level/Location} {Autoscale} Average the signal across 10 traces {Average/Sweep} {Averaging} {Running

Average} {Average} [10] {Enter} Set up a Delta Marker that spans from the center frequency to a 885 kHz offset

{Marker} {Type: Off/Normal/∆} [885] {kHz}


Record the power level delta:______________________________ Let�s now crank up the power of our base station transmitter (the ESG-D) to 20 dBm (100 mW) and see the effects of transmitting at a higher power. Instructions: ESG-D series signal generator Keystrokes: ESG-D series signal

generator Set the amplitude to +20 dBm [Amplitude] [20] {dBm} Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Autoscale the signal {Level} {Autoscale} Reset the delta markers by turning the markers off

{Marker} {Type: Off/Normal/∆}

Turn on delta markers {Type: Off/Normal/∆} Record the power level delta:______________________________ Explain why the power level delta value has changed. What effect will this phenomenon have on system capacity?


The power level delta changed because some device in the transmitter has become saturated and gone into its nonlinear region of operation. As a consequence much more interference is being transmitted in the adjacent frequency channels. The added interference will decrease system capacity.


4. Perform channel scanner measurements on a GSM signal

Channel scanner measurements are beneficial in making AMPS, TDMA, and GSM measurements to verify consistent power level settings on all the transmit channels. Configure the ESG-D to generate a GSM signal at 937 MHz (Forward Link Absolute Radio Frequency Channel Number (ARFCN) 10). Instructions: ESG-D series signal generator Keystrokes: ESG-D series signal

generator Preset Test set [Preset] Generate a GSM signal and turn the RF carrier on

[Mode] {Real Time I/Q Baseband} {GSM} {Data Format: Pattern/Framed} {GSM: Off/On} {RF: On/Off}

Set the carrier frequency to ARFCN 10 for the forward link

{More (1 of 2)} {Freq Channels} {Freq Channels: Off/On} {Channel Number} [10] {Enter} {Channel Band} {More (1 of 2)} {P-GSM Base}

Set the amplitude to -10 dBm [Amplitude] [+/-] [10] {dBm} Configure the E7495A to scan the GSM channels. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select the Channel Scanner option under the Spectrum Analyzer/Tools menu

[Mode] {Spectrum Analyzer/Tools} {Channel Scanner}

Set the Units to Channels {Units: Freq/Chan} Set the Channel Standard to GSM 900 {Chan Std}

Using the RPG dial highlight the “GSM-900” on the Format List. {Select}

Set the Start Channel to 10 {Start Chan} [10] {Fwd} Set the Channel Standard Step Size to 1 {CS Step Size} [1] {Enter} View 8 GSM channels {Num Chans} [8] {Enter}


Notice the power in the 200 kHz GSM channel is displayed above the red bar representing that channel. Record the average power in the desired GSM channel:_______________________________ When doing channel scanner measurement, it defaults to average power and displays the average power of the signal. Since GSM is a bursted signal, it is not on all the time. When doing average detection on a bursted signal, it is averaging over time therefore it doesn�t represent the true power in a burst (each channel). When measuring power of bursted signal like GSM, it is preferred to use peak power to determine the actual power. Let�s now change the power detector to peak: Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Change the power detector to peak {Setup} {Power Detector Avg/Pk} Record the peak power in the desired GSM channel:_______________________________ Can you explain the benefit of measuring the power in each GSM channel (ARFCN) using the Channel Scanner? GSM service providers want the same transmit power level in all the GSM channels. Typically a technician servicing a GSM transmitter brings up 1 GSM channel at a time and verifies its channel power is within +/- 1 dB of all the other GSM channels. Coverage holes could exist on


the channels with lower power and the higher power signals could create added interference. The El Gato GSM channel scanner streamlines this process. Instructions: ESG-D series signal generator Keystrokes: ESG-D series signal

generator Set the power to +10 dBm [Amplitude] [10] {dBm} Record the power in the desired GSM channel:_______________________________ Instructions: ESG-D series signal generator Keystrokes: ESG-D series signal

generator Turn off the RF carrier [RF: On/Off] Disconnect the 10� test cable from the 40 dB attenuator


5. Measure the average power of a GSM signal

Average power is measured over the full bandwidth of the signal over several cycles and can be measured on an active base station. Only the desired signal should be present when measuring average power. If the base station is transmitting other GSM channels, it is recommended to turn off all the other GSM channels while performing the average power measurement on the signal of interest. We will use the same GSM signal transmitted at the Forward Link ARFCN 10 (937 MHz) that we used in the GSM channel scanner measurements. Power measurements require �zeroing� and calibration of the power meter. The power meter should be zeroed if or when any of the following conditions occur:

� when a 5° C change in temperature occurs. � when you change the power sensor. � every 24 hours. � prior to measuring low level signals. For example, 10 dB above the lowest specified power for your power sensor.

The power meter should be calibrated any time the test set�s power cycled on and off. NOTE Configure the E7495A to measure the average power of the GSM signal. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select the Power Meter option [Mode] {Power Meter} Select Zero under the Zero/Calibrate menu and follow the instructions of the Zero Wizard

{Zero}

Connect the Power Sensor to the Power Sensor Lead and then connect the Power Sensor Lead to the Sensor port on the top of the unit

Note: It is suggested to remove the power sensor from any power source prior to zeroing the power meter.

Select the Continue button {Continue} We have �zeroed� the power meter and are now ready to calibrate it. Calibration sets the gain of the power meter using a 50 MHz 1 mW calibrator as a traceable power reference. The power meter�s �Power Ref� output is used as the signal source for calibration. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Verify the reference calibration factor of the power sensor with that displayed on the Ref CF button. Note: The Reference Cal Factor value of your sensor may differ slightly from 100 %. If so, enter the value from your power sensor.

{Ref CF} [98] {%}

Select Calibrate under the Zero/Calibrate menu {Calibrate}


and follow the instructions of the Calibration Wizard Maintain the same connections in the Zeroing process with the additional connection of the Power Sensor to the Power Ref port on the top of the unit

Select the Continue button {Continue} We are now ready to make an average power measurement. Making power measurements on a base station requires the use of the high-power 40 dB attenuator supplied with the unit. Why is a high power attenuator is required in making base station power meter measurements? A high power attenuator is required in making base station power meter measurements in order to protect the power meter and sensor head from excessively high power signals that would damage them. The insertion loss of the 40 dB attenuator must be accounted for while making power measurements. Previously in section 1.3 of this lab we measured the insertion loss of this 40 dB attenuator and stored this loss as the Power Meter (PM) Loss. To make an average power measurement we will first set the calibration factor value for the frequency of the signal we will measure, connect to the base station as close as possible to the power amplifier/duplexer output, and then take a reading. For this lab the ESG-D signal generator will serve as the base station transmitter. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Disconnect the power sensor from the Power Ref port

Set the calibration factor for the frequency of the GSM signal to be measured: 937 MHz. Note: The calibration factor can be read from the table on the power sensor.

{Cal Factor} [97] {%}

Set the High and Low Limits {Setup} {Limits: On/Off} {Lo Limit} [+/- 5] {dBm} {Hi Limit} [15] {dBm}

Instructions: ESG-D series signal generator Keystrokes: ESG-D series signal

generator Connect the power sensor to the 40 dB attenuator which is connected to the RF Output of the ESG-D.

Turn on the RF carrier [RF: On/Off] Set the amplitude to 0 dBm [Amplitude] [0] {dBm}


Notice the area within the limits is green and any area outside the limits is red. Record the average power of the GSM signal:____________ in dBm and _____________ in mW. Let�s now crank up the power of our base station transmitter (the ESG-D) to 20 dBm (100 mW) and measure the average power once again. Instructions: ESG-D series signal generator Keystrokes: ESG-D series signal

generator Set the amplitude to +20 dBm [Amplitude] [20] {dBm} Notice the warning on the screen that the power is outside the limits. Record the average power of the GSM signal:____________ in dBm and _____________ in mW. Why is it important to accurately measure average transmit power? Average power measurements provide a key metric in transmitter performance. Transmit power must be set accurately to achieve optimal coverage in wireless networks. If transmit power is set too high due to inaccurate power measurements, unnecessary interference can occur. If transmit power is set too low, coverage gaps or holes may exist. Either case affects system capacity and translates to decreased revenue for service providers. Instructions: ESG-D series signal generator Keystrokes: ESG-D series signal

generator Turn off the RF carrier [RF: On/Off] Disconnect the 40 dB attenuator


Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Disconnect the 40 dB attenuator, power sensor, and power sensor lead


6. Make CDMA transmitter measurements

CDMA transmitter measurements verify proper transmitter performance and are typically made with the base station out-of-service. Important metrics are frequency error, PN and time offsets, channel power, waveform quality (estimated Rho), carrier feedthrough, noise floor, Pilot power, and the delta powers between the Pilot and the Page, Sync and Quick Paging code channels. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Connect the 10� test cable from the RF Output of the ESG-D the RF In port of the E7495A.

Connect the GPS antenna to the GPS antenna port

You would typically connect to the coupled port on the base station when making CDMA transmitter measurements. Configure the ESG-D to generate a cdmaOne signal at 870 MHz. Instructions: ESG-D series signal generator Keystrokes: ESG-D series signal

generator Preset the ESG-D [Preset] Set the center frequency to 870.03 MHz (Cell Band Forward Link Channel 1)

[Frequency] [870.03] {MHz}

Set the amplitude to �10 dBm [Amplitude] [+/-] [10] {dBm} Go to cdmaOne (IS-95) under the built-in Arb Waveform Generator menu

[Mode] {Arb Waveform Generator} {CDMA Formats} {IS-95A}

Generate a 9-channel cdmaOne forward link signal

{CDMA: Off/On} [RF On/Off]

Configure the E7495A to analyze the 870 MHz cdmaOne transmit signal. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select the CDMA Analyzer option [Mode] {TX Analyzer} {CDMA Analyzer} Select the North American Cellular CDMA channel standard

{Chan Std} Using the RPG dial highlight the “North American Cellular CDMA” channel standard. {Select}

Set the Units to Channel {Units: Freq/Chan} Set the channel to Forward Link Channel {Channel} [1] {Fwd} Set the Time Reference to Internal GPS {Fr/Time Ref} { GPS (Freq & Time)}


The CDMA TX Analyzer screen is divided into 2 sections: the �trace display� and the �metric display�. The trace display contains a code domain power display. In this display 128 Walsh codes are shown in a �bit-reversed� order to represent the combined code channels for the varying data rate traffic channels. The Y-axis labels display the relative (dB) or absolute power (dBm), threshold level, and dB/division. The X-axis labels display active channel numbers. Active code channels shown on the display include:

• Pilot (red) • Page (green) • Sync (blue) • Quick page (light blue) • IS-95 traffic (yellow) • cdma2000 traffic (orange) • Unknown traffic (tan) • Noise (light gray)

The metric display shows 12 measurement parameters displayed below the trace display. Record the Estimated Rho:_____________ Carrier Feedthrough:_______________ and


Pilot Power:______________ Notice the time reference indicator at the bottom right corner of the screen. The text indicates which time reference you have chosen and the LED color indicates the lock condition. A green LED indicates a locked condition whereas a red LED indicates an unlocked condition. What is the benefit of using an Internal GPS time reference versus using the External Even Second time reference from the base station? Using the External Even Second time reference synchronizes the E7495A to the base station�s time reference. If the base station has lost its GPS lock, it will be out of sync with the rest of the system (other base stations) and an �island cell� effect can occur. In this case the base station would not be able to hand off users to the other cells and the call would be dropped when the user leaves the coverage area of this cell. Therefore, it is better to use the Internal GPS time reference if possible. The Active Channel Threshold Level is an advanced setting that can be set to indicate which code channels are considered active. Any code channels exceeding this power level are considered active traffic channels and any code channels below this power level are considered inactive (or noise). A horizontal red line on the screen represents the threshold level. The test set can set this level automatically, or you can manually enter a value.

In Auto mode the threshold level moves as the noise fluctuates. The threshold level is set by the test set at an optimal offset above the average noise floor. If you choose Auto mode, you can alter the Auto Threshold Offset. The recommended and default setting is 0 dB. A negative value moves the threshold lower (closer to the noise floor) and is a more aggressive setting that increases the likelihood of interpreting an inactive channel as active. A positive value moves the threshold higher (away from the noise floor) and is a more conservative setting that increases the likelihood of interpreting an active channel as inactive. In Manual mode the threshold level is fixed and does not move as the noise fluctuates. From the trace display how many active code channels are present?

Let�s set a more aggressive Auto Threshold Offset and view the results.

Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Set the Active Channel Threshold Level to Auto mode and set the Auto Threshold level to a more aggressive setting.

{Setup} {Thres Level: Auto/Manual} {Auto Thres Offset} [+/- 3] {dB}

Perform a single sweep {Average/Sweep} {Single} Notice the threshold level (red horizontal line) is 3 dB lower than before.


Now how many active code channels are present? How many are considered noise? Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Return the Auto Threshold Level to 0 dB {Setup} {Auto Thres Offset} [0] {dB} Perform continuous sweeps {Average/Sweep} {Continuous}

Let�s �manually� set a more aggressive Threshold Level and view the results.

Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Set the Active Channel Threshold Level to Manual mode and set the Threshold Level to a more aggressive setting.

{Setup} {Thres Level: Auto/Manual} [+/- 42] {dB}

Perform a single sweep {Average/Sweep} {Single} How many active noise channels are present? When would it be beneficial to know which channels are considered noise? Knowing which inactive code channels are contributing the most noise to the overall CDMA channel may provide clues to the source of noise � possibly a bad channel card in the base station, etc.

Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Return the Active Channel Threshold Level to Auto mode

{Setup} {Thres Level: Auto/Manual}

Perform continuous sweeps {Average/Sweep} {Continuous} Instructions: ESG-D series signal generator Keystrokes: ESG-D series signal

generator Turn off the ESG-D [White Power Button] Disconnect the 10� test cable from the ESG-D and the E7495A


7. Make “Over-the-Air” CDMA measurements

CDMA Over Air measurements are a quicker method of verifying CDMA transmitter performance. These transmitter measurements can be made on a base station from the convenience of your vehicle without taking the base station out-of-service. Over Air measurements are especially useful in maintaining hard to access cell sites such as pole top base stations.

An important consideration in making CDMA Over Air measurements is the location of where you are making measurements. You must be reasonably close to the base station with no obstructions between you and the base station antennas. If you are using Internal GPS for the time reference, the GPS antenna must be able to �see� the satellites to obtain lock. Using Internal GPS for the time reference has the same advantages mentioned for CDMA transmitter measurements (�island cell� detection).

Configure the E7495A to analyze the PCS Channel 500 transmit signal over the air. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Verify the GPS antenna is connected to GPS antenna port

Connect the PCS band antenna to the RF In Port

Select the CDMA Over Air option [Mode]{Over Air} {CDMA Over Air} Select the North American PCS CDMA channel standard

{Chan Std} Using the RPG dial highlight the “North American PCS CDMA” channel standard. {Select}

Set the Units to Channel {Units: Freq/Chan} Set the channel to 500 Forward {Channel} [500] {Fwd} Set the Time Reference to Internal GPS {Fr/Time Ref} { GPS (Freq & Time)}


The CDMA Over Air Analyzer screen is divided into 3 sections: the �code domain trace display�, �strongest pilot trace display�, and the �metric display�. The code domain trace display contains 128 Walsh codes, which are shown in a �bit-reversed� order to represent the combined code channels for the varying data rate traffic channels. The Y-axis labels display the relative (dB) or absolute power (dBm), threshold level, and dB/division. The X-axis labels display active channel numbers. Active code channels shown on the display include:

• Pilot (red) • Page (green) • Sync (blue) • Quick page (light blue) • IS-95 traffic (yellow) • cdma2000 traffic (orange) • Unknown traffic (tan) • Noise (light gray)

The strongest pilot trace display contains the Pilot Dominance and Multipath Power parameters. Awareness of these two parameter values helps you be sure that you are making valid measurements on the sector of interest. The metric display shows 18 measurement parameters displayed below the trace display. Notice the Internal GPS reference indicator at the bottom right corner. A green LED indicates a locked condition whereas a red �X� indicates an unlocked condition. Also notice the 3 strongest pilots in the �strongest pilots display�.

Record the strongest pilot PN:_________________ and the next strongest pilot PN:___________


The Pilot from the desired sector should be the strongest Pilot captured by the test set. Accurate Over Air measurements require a very dominant Pilot signal and very low multipath power.

Record the Pilot Dominance:________________ and Multipath Power:_____________________

Do these values provide accurate CDMA Over Air measurements?

The Pilot Dominance is the difference in the amplitude of the strongest pilot channel and the second strongest pilot channel and is expressed in dB. Ideally this value should be very large (> 15 dB). Multipath power is the amount of power (expressed in dB) of the dominant pilot signal that is dispersed outside of the main correlation peak due to multipath echoes coming at the same time as the main, desired signal. Ideally, this value will be very small (< 0.1 dB).

The table below shows the quality of the Over Air code domain measurements with respect to Pilot Dominance and Multipath Power. Measurement Quality

Pilot Dominance Multipath Power

Very Good > 15 dB < 0.1 dB Fair > 10 dB < 0.4 dB Marginal > 8 dB < 0.7 dB

The default measurement limits for Pilot Dominance and Multipath Power are set to give �fair� measurement quality. If these limits are met, the Pilot Dominance and Multipath Power values will be displayed in green. When the Pilot Dominance and Multipath parameters are outside the acceptable limits, the parameters will turn red. If this occurs, you should move to a different location that meets the �fair� criteria defined above. Record the Waveform Quality (Estimated Rho):_________________ Is the Estimated Rho value acceptable? If not, how could it be improved? The CDMA base station standard specifies that Estimated Rho must be greater than 0.912. Typical values for a healthy base station are greater than 0.94. When measuring Estimated Rho over-the-air, these values can only be achieved under very good conditions for multipath power and pilot dominance. For example, a Multipath Power of < 0.1 dB and a Pilot Dominance of > 15 dB is required to measure Estimated Rho of 0.912. Therefore, moving to a location that provides higher Pilot Dominance and lower Multipath Power should improve the Estimated Rho value.


For more information on the effects of pilot dominance and multipath power on Rho performance see Appendix A at the end of the lab procedures.

As mentioned earlier the location at which CDMA Over Air measurements are made is critical � measurements made at a later date should be taken at the same location. To assist in accurately finding the same location a GPS lat/long reading can be displayed.

Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Display the GPS Location {Level/Location}{GPS Location: Off/On} Record the Latitude:______________________ and Longitude:___________________________

Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Turn off the GPS Location display GPS Location: Off/On}

Record the Utilization:__________________ and the Peak Utilization:____________________ What is meant by Utilization? Utilization is a ratio of the active Walsh codes to the total 128 Walsh codes, expressed in percent. Even though active control channels such as the pilot are included in the utilization measurement, utilization is an indication of the traffic that is being carried by the base station. Another indication of the current capacity of the base station is the Amplifier Capacity measurement. The Amplifier Capacity measurement is an estimate of the amount of power amplifier capacity that is being used, expressed in percent of maximum. The Amplifier Capacity properties must be properly set to make valid Amplifier Capacity measurements. The Amplifier Capacity measurement metrics are: Amplifier Capacity, Peak Amplifier Capacity, and Average Amplifier Capacity. A CDMA base station is typically set up with a specified amount of power allocated to the Pilot Channel, and specified power settings of the Paging and Sync Channels are defined relative to the Pilot Channel. Occasionally, the Paging and Sync Channels power settings will also be specified in absolute power units (Watts or dBm). Given the Pilot, Paging, and Sync power setup values and the maximum power output of the amplifier, the percentage amplifier capacity setup parameters can be determined. Set the Amplifier Capacity parameters. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Turn on the Amplifier Capacity measurements {Reset/Amp Cap} {Amp Cap: Off/On} Set the Pilot power to 0.8 W {Pilot Power} [0.8] {W} Set the Maximum Power to 8 W {Max PA Pwr} [8] {W} Set the Delta Page Power to �4 dB {Delta Page Pwr} [+/- 4] {dB} Set the Delta Sync Power to �9 dB {Delta Sync Pwr} [+/- 9] {dB}


Record the Amplifier Capacity:______________ and the Peak Amplifier Capacity:____________

Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Disconnect the GPS antenna Disconnect the PCS band antenna from the RF In port


8. W- CDMA transmitter measurements in the code domain

W-CDMA (UMTS) transmitter measurements verify proper transmitter performance of a UMTS Base Station (referred to as a Node B in UMTS world) and are typically made with the base station out-of-service under test conditions. Non-intrusive measurements can also be made on live network if a Monitor or Test port is present. This is usually a coupled port and power levels are �20 or �30 dB down from the main Tx output power RF path which can exceed 10Watts. Important metrics are frequency error, error vector magnitude (EVM), peak code domain error (PCDE), channel power, carrier feedthrough, code domain noise floor, CPICH power, and the delta powers between CPICH and P-CCPCH, S-CCPCH, PICH, P-SCH and S-SCH. These latter measurements are all performed in the �Code Domain� and are sometimes referred to as Code Domain Power measurements.

One of the defining elements of a 3G system is high-speed data transmission. The 3GPP standard allows for multiple data rates depending on the application. This flexibility requires complex processing in both the transmitter and receiver to retain information quality and still transfer a variety of user information in the noisy spread spectrum environment. The code domain power (CDP) measurements allows us to quickly verify the operation of a 3GPP transmitter. In addition, it can give a high-level evaluation of modulation quality, channel power, and signal-to-noise in the code-domain.

In most field-testing situations, it is preferable to use the frequency reference provided by the Node B to facilitate finding and locking to the Tx output signal. However, use of the GPS is advised when a network-independent time reference is desired. For the RF connection, you would typically connect the E7495 RF Input Port to the coupled output port on the base station when making W-CDMA transmitter measurement. This port may be labeled �TEST�, �MONITOR� or simply �MON�. In this way, the base station can remain on-air while Tx measurements are being made. If the RF Input port of the instrument is connected directly to the Tx RF output, then the base station must be taken out of service (or at least that sector).

CAUTION: If testing at the direct Tx RF Output of the Node B, be sure to use the high power 40 dB high power attenuator or a directional coupler with at least –30 dB coupling factor to avoid damaging the E7495!!


Note on how front panel keys are identified for this lab: Keystrokes surrounded by [Brackets] indicate hard keys located on the front panel of the test set, while keystrokes surrounded by {Braces} indicate soft keys located on the left and/or right side of the display. Let�s connect the ESG RF output port to the E7495 RF Input. Instructions: E7495X BS Test Set Keystrokes: E7495X BS Test Set Connect the 10� test cable from the RF Output of the ESG the RF In port of the E7495X .

Connect the GPS antenna to the GPS antenna port (optional- we can use the internal reference if GPS is unavailable

Configure the ESG to generate a W-CDMA (UMTS) signal at 2.145GHz Instructions: ESG series signal generatorInstructions: ESG series signal generatorInstructions: ESG series signal generatorInstructions: ESG series signal generator Keystrokes: ESG series signal generatorKeystrokes: ESG series signal generatorKeystrokes: ESG series signal generatorKeystrokes: ESG series signal generator Preset the instrument [Preset] Set the center frequency to 2.145 GHz [Frequency] [2.145] {GHz} Set the amplitude to –5 dBm [Amplitude] [+/-] [5] {dBm} Go to W-CDMA under the built-in Arbitrary Waveform Generator menu

[Mode] {W-CDMA} {Arb W-CDMA (3GPP)}

Generate a W-CDMA signal that includes a PCCPCH, a DPCH, and a SCH physical channel and change the spread code of DPCH channel to 10

{W-CDMA Select} { PCCPCH + SCH +1 DPCH} {W-CDMA Define} {Edit Channel setup} highlight the spread code for DPCH channel {Edit Item} [10] {Enter} [Return][Return]{W-CDMA: Off/On} [RF On/Off]

ADVANCED TOPIC: the E7495 also has a manual mode in which the scramble code (SC) can be entered by the user instead of being auto-detected by the instrument. If the SC is known by the user, then this value can be entered and the E7495 can decode and display the CDP of the signal, even if no P-SCH and S-SCH are present (a CPICH must be present however). In normal operating conditions, these sync channels are available, and so the P-SCH and S-SCH are used by the E7495 (and UMTS mobiles) to determine the correct sequence of scrambling codes required to demodulate the DPCH channels. Configure the E7495X to analyze the 2.145 GHz transmit signal. The E7495A/B will make this measurement with any combination of physical channels as long as the sync (PSCH & SSCH) and common pilot channel (CPICH) are active. Instructions: E7495X BS Test Set Keystrokes: E7495X BS Test Set Select the W-CDMA (UMTS) Analyzer option [Mode] {TX Analyzer} {W-CDMA (UMTS)

Analyzer} Set the Units to Freq {Freq/Chan/Time Ref}{Units: Freq/Chan} Set the Frequency to 2.145 GHz {Frequency} [2.145] {GHz} Set the Time Reference to Internal Reference {Fr/Time Ref} {Internal Ref}


The active channels are clearly seen as the tall colored bars in the code domain display. The W-CDMA (UMTS) Tx analyzer CDP screen is divided into 4 sections as follows:

��The top-left graph (Full View) shows the power in all 512 channels (spread codes). The light blue section on the bottom bar corresponds with the section displayed in zoom view (described below). The red bar across the graph represents the active channel threshold. The traffic channel displays in orange color, the rest are in the color shown in the control view.

��The top-right graph (Control View) shows the power in the control channels as follows:

Acronym Full Name Which Display Area CPICH Common Pilot Channel Visible in all views (red bar)

PCCPCH Primary Common Control Physical Channel

Visible in all views (yellow bar)

SCCPCH Secondary Common Control Physical Channel

Visible in all views (green bar)

PICH Paging Indicator Channel Visible in all views (light blue bar) PSCH Primary Sync Channel Visible ONLY in the Control View (blue bar) SSCH Secondary Sync Channel Visible ONLY in the Control View (purple bar)

��The lower-left graph (Zoom View) shows the power in the section of the graph

highlighted in light blue in the top-left graph, a section of 32, 64, or 128 codes.

��The bottom portion (Metrics View) displays the current measurement metrics.


NOTE: In W-CDMA (UMTS), the PSCH and SSCH are not assigned spread codes and therefore do not appear in the code domain power display (Full View). The E7495x added a control channel graph view (Control View) for these two Sync channels to measure power only, since there is no spread code associated with these channels. They have special non-orthogonal scrambling codes and are only actually �on� 10% of the time. Let�s modify the signal using the flexible Arbitrary Signal editor in the ESG. We can configure a complex W-CDMA signal with a variety of code channels, data rates, and power levels. This allows you to create almost any test signal. Instructions: ESG series signal generator Keystrokes: ESG series signal generator Modify the signal to add two high data rate channels.

{W-CDMA Define} {Edit Channel Setup} {Insert Row} {DPCH} {120 ksps} {DPCH} {240 ksps} {More}{PICH} {[Return]

Normalize all powers to 0 dB {Adjust Code Domain Power} {Scale to 0dB}

Apply new channel settings [Return] {Apply Channel Setup} You have now added two high-speed data users to the 3G signal plus a paging channel. Even though the content of this signal has changed significantly, the signal can still look similar in the frequency and time domain. To see how the channel characteristics have changed, re-measure the code domain power. Be sure the ESG finishes generating the waveform before proceeding.


Now the two DPCH�s and the PICH channel we added are clearly visible on the code domain display. The PICH (paging indication channel) however is not visible on the control channel view display (top right graph) and on the measurement metrics display. You will need to enable the PICH and SCCPCH on the E7495x to view the power in the control channel view and metrics display. Let�s enable the PICH channel on the E7495x. Instructions: Instructions: Instructions: Instructions: E7495X BS Test Set Keystrokes: Keystrokes: Keystrokes: Keystrokes: E7495X BS Test Set Enable the PICH channel {Setup} {PICH 256 (16) Disabled}{PICH

Enable Off/On}{Channel} [10] {Enter}

Now the PICH channel power appears on the control view display and also on the metrics view (bottom display). Also notice the color of the PICH channel has changed to light blue on the code domain power display. The wider bars on the code domain display represent higher data rate channels. The widest bar on the right is the 240ksps channel. Let�s zoom in closer on this channel and use a marker to verify the power and symbol rate Instructions: E7495X BS Test Set Keystrokes: E7495X BS Test Set Zoom into the widest bar on the Code domain display (this is the 240 ksps channel)

{Display} {View: Zoom/Full} { Position} [278] {Enter} {Width 32/64/128}

Place marker on this channel {Marker} {Type: Normal} {Marker to Peak} With marker 1 active, use the knob to move marker to the desired spread code

Rotate the dial slowly to left or right to select the 240ksps channel


Record (for the widest bar): Data Rate __________ ksps Relative Channel Power Level __________ dB. Zoom into the CPICH (Common Pilot Channel ) and use a marker to identify the CPICH Instructions: Instructions: Instructions: Instructions: E7495X BS Test Set Keystrokes: Keystrokes: Keystrokes: Keystrokes: E7495X BS Test Set Zoom into the CPICH channel (always code 0) {Display} {View: Zoom/Full} {Position} [0]

{Enter} {Width 32/64/128} Place marker on the CPICH channel {Marker} [0] {Enter}

Notice the smaller the number you select on zoom width, the wider the display of each code, letting you zoom in on a particular codes. If you select width = 32, as we did here, you will also see the channel information.

What is the power level of the CPICH? ________ What is the data rate of the CPICH? ________ What is the spreading factor (SF) of the CPICH? _______ What is the spread code of the CPICH? __________


ADVANCED TOPIC Spread Codes, Marker Position, and OVSFs (Orthogonal Variable Spread Factors) The CPICH channel is always at 15ksps and it uses spread code 0. When you put a marker on CPICH channel it should read a value of '256 (0)' � The �256� identifies this channel as using a spreading factor (also known as OVSF) of 256 and (0) indicates it is a spread code 0.

You can use the following formula to determine the SF : SF =3.84Msps divided by channel’s data rate in Msps So if the CPICH is transmitted at 15ksps, the OVSF must be 256 in order to get the final correct chip rate of 3.84Mcps (256 = 3.84Mcps / 0.015Msps) For the DPCH's, they can be at different symbol rates and different spread codes. In this lab we have DPCH at 30ksps (spread code 10), 120 ksps (spread code 8) and 240 ksps (spread code 9). But notice that when you place a marker on these particular channels, the spread code indicated on the Marker Position window does not seem to what you would expect based on the range of 0 to 512. Can you figure out the relationship between the Spread Code indicated on the ESG, the marker position readout, and the expected OVSF number based on where the DPCH bar is located along the X-axis of the CDP display? You can use this formula to predict the marker position: Marker position = (512 divided by the SF) X the Marker’s Spread Code Value (the value that is shown in the marker readout in parentheses when placed on that particular DPCH). For a 30ksps DPCH, it should read '128(10)' [the 128 comes from 3.84Mcps/30ksps and the 10 is the spread code of this DPCH as shown on the ESG]. Where does this particular DPCH bar fall on the Code Domain Full View? Position _______

Channel Power: How does the channel power recorded earlier correlate to the power level of the various channels as set up in the ESG? Let�s go back to the ESG�s channel editor screen to see what power level the CPICH channel was originally set to.

Instructions: ESG series signal generatorInstructions: ESG series signal generatorInstructions: ESG series signal generatorInstructions: ESG series signal generator Keystrokes: ESG series signal generatorKeystrokes: ESG series signal generatorKeystrokes: ESG series signal generatorKeystrokes: ESG series signal generator View the W-CDMA channel editor screen [Mode] {W-CDMA} {Arb W-CDMA (3GPP)}

{W-CDMA Define} {Edit Channel Setup}


Look at the Power column for the CPICH channel. This value should match the value recorded above to within a few hundredths of a dB. Record: Power Level Set (from ESG) _______ dB ; Power Level Measured (from E7495x) ________ dB. Metric Display: Modulation Accuracy is one of the 15 reported metrics on the bottom display of the E7495x Base Station Test when in W-CDMA (UMTS) Tx Analysis mode.

Rho is a very popular measurement in CdmaOne/Cdma2000 for measuring modulation accuracy. For W-CDMA (UMTS), EVM (Error Vector Magnitude) is the metric used to measure modulation accuracy of a transmitter. EVM is a measure of the difference between the measured waveform and the theoretical modulated waveform (the error vector). The 3GPP standard requires the EVM not to exceed 17.5% for a specific Test Model (Test Model 4)

In W-CDMA (UMTS), specifically to address the possibility of uneven error power distribution, the EVM measurement has been supplemented by another test called Peak Code Domain Error (PCDE). PCDE is defined as the maximum value for the code domain error for all codes (both active and inactive). The 3GPP standard requires the PCDE not to exceed �33dB at a spreading factor of 256 (Test Model 3).

Record the EVM:_____________ PCDE:_______________ ADVANCED TOPIC: 3GPP uses specific Test Models with known characteristics and specific traffic channels and symbol rates activated to characterize EVM and PCDE. However, it is still useful to look at EVM and PCDE with live traffic (non Test Model cases). Under most conditions, EVM and PCDE should still pass the 17.5% and �33dB limits respectively.


The Active Channel Threshold Level is an advanced setting that can be set to indicate which code channels are considered active. Any code channels exceeding this power level are considered active traffic channels and any code channels below this power level are considered inactive (or noise). A horizontal red line on the screen represents the threshold level. The test set can set this level automatically, or you can manually enter a value.

In Auto mode the threshold level moves as the noise fluctuates. The threshold level is set by the test set at an optimal offset above the average noise floor. If you choose Auto mode, you can alter the Auto Threshold Offset. The recommended and default setting is 0 dB. A negative value moves the threshold lower (closer to the noise floor) and is a more aggressive setting that increases the likelihood of interpreting an inactive channel as active. A positive value moves the threshold higher (away from the noise floor) and is a more conservative setting that increases the likelihood of interpreting an active channel as inactive. In Manual mode the threshold level is fixed and does not move as the noise fluctuates. From the trace display how many active code channels are present? ____________________

Let�s set a more aggressive Auto Threshold Offset and view the results.

Instructions: E7495X BS Test Set Keystrokes: E7495X BS Test Set Set the Active Channel Threshold Level to Auto mode and set the Auto Threshold level to a more aggressive setting.

{Setup} {Thres Level: Auto/Manual} {Auto Thres Offset} [+/- 5] {dB}

Change the display to Full mode [Display] {View Zoom/Full} Perform a single sweep {Average/Sweep} {Single} When selecting the full view display, the top-left graph shows the first 256 code channels: 0-255, and the bottom-left graph shows the power in the second 256 code channels: 256-512. Notice the threshold level (red horizontal line) is 5 dB lower than before. Now how many active code channels are present? ____________________________ How many are considered noise? ________________________ Instructions: E7495X BS Test Set Keystrokes: E7495X BS Test Set Return the Auto Threshold Level to 0 dB {Setup} {Auto Thres Offset} [0] {dB} Perform continuous sweeps {Average/Sweep} {Continuous}


Let�s �manually� set a more aggressive Threshold Level and view the results.

Instructions: E7495X BS Test Set Keystrokes: E7495X BS Test Set Set the Active Channel Threshold Level to Manual mode and set the Threshold Level to a more aggressive setting.

{Setup} {Thres Level: Auto/Manual} [+/- 45] {dB}

Perform a single sweep {Average/Sweep} {Single} How many active noise channels are present? _________________________ When would it be beneficial to know which channels are considered noise? _____________________________________________________________________________ _____________________________________________________________________________

Knowing which inactive code channels are contributing the most noise to the overall W-CDMA channel may provide clues to the source of noise � possibly a bad channel card in the base station. Instructions: E7495X BS Test Set Keystrokes: E7495X BS Test Set Return the Active Channel Threshold Level to Auto mode

{Setup} {Thres Level: Auto/Manual}

Perform continuous sweeps {Average/Sweep} {Continuous}


9. W-CDMA (UMTS) Adjacent Channel Leakage Power Ratio (ACLR) Measurements

One of the most important measurements on RF signals for digital communication systems is the leakage power into the adjacent channels. A quantitative figure of merit is adjacent channel power ratio (ACPR) or adjacent channel leakage ratio (ACLR). The adjacent channel leakage ratio (ACLR) measurement determines how much of the transmitted power is allowed to leak into the first and second neighboring carrier (high side and low side). The measurement is defined as the ratio of the average power in the adjacent frequency channel to the average power in the transmitted frequency channel. It is reported in dBc Set ESG for W-CDMA Base-Station signal generation as follows:

Instructions: ESG series signal generator Keystrokes: ESG series signal generator Preset the instrument [Preset] Set the center frequency to 2.145 GHz [Frequency] [2.145] {GHz} Set the amplitude to �10 dBm [Amplitude] [+/-] [10] {dBm} Go to W-CDMA under the built-in Arb Waveform Generator menu

[Mode] {W-CDMA} {Arb W-CDMA (3GPP)}

Generate a W-CDMA TEST Model 1 with 16 DPCH

{W-CDMA Select} {Test Models} { TEST Model 1 w/ 16 DPCH}

Activate the format {W-CDMA: Off/On} [RF On/Off] Test Model is the test condition for Base station conformance test. Under 3GPP TS 25.141, 4 types of test models are defined. Each test model consists of PCCPCH (Primary Common Control Physical Channel), PICH (Paging Indication Channel), CPICH (Common Pilot Channel), SCH (Synchronization Channel) and some DPCHs (Dedicated Physical Channels).

Set the E7495X to make ACP measurement: Instructions: E7495X BS Test Set Keystrokes: E7495X BS Test Set Select the Spectrum Analyzer option [Mode] {Spectrum Analyzer/Tools}

{Adjacent Channel Power} Set the Units to Frequency {Units: Freq/Chan} Set the Frequency to 2.145 GHz {Frequency} [2.145] {GHz} Set the Format type to list and select UMTS ACP format

{ACP Format} {Format type Chan/List/Cust} {Format List} Using the RPG dial highlight the “UMTS” on the Format List. {Select}


Record: ACLR levels at the 5 MHz offset: ACP 1 Low______________ dBc. ACP 1 High_______________ dBc. Notice the measurement is shown as a bar graph of the power levels at different offsets. This allows for a quick reading of respective powers. Also notice the bar graph is green with �P� on the bar graph indicating the ACLR measurement passes at the 5MHz and 10MHz offsets. Let�s change the Power limit of the 5MHz adjacent carrier to more stringent value on the E7495x and see if the measurement passes or fails Instructions: E7495X BS Test Set Keystrokes: E7495X BS Test Set Change the power limit for the 1st adjacent carrier

{Setup}{Power Limits} {Adj Chan 1 High Limit}[+/- 60] {dB}


Now the measurement fails and the bar graph for the 5MHz offset turns to red and shows �F� flag. The 3GPP standard requires the adjacent channel power leakage ratio to be better than

45dB at 5MHz offset and 50 dB at 10MHz offset .

Let�s go back to the Tx WCDMA Analysis CDP screen to see how the test model looks in the code domain: Instructions: E7495X BS Test Set Keystrokes: E7495X BS Test Set Switch back to Tx Analyzer, WCDMA Analysis CDP screen

[Mode] {TX Analyzer} {W-CDMA (UMTS) Analyzer}{Mkr} [32]

Note that the instrument remembers the previous frequency and previous configuration with PICH enabled etc.


10. Perform T1 line measurements

Each base station is connected to the wireline network via a T1 line. The T1 line transports data from calls carried by the base station. The integrity of the T1 line must be tested. There are many different ways to test a T1 line, some of which can be very complicated. The complexity of T1 testing certainly parallels or possibly exceeds that of RF testing at a cell site. For a detailed description of T1 specifics please refer to Appendix B at the end of the lab procedures. The test set performs both Out-of-Service and In-Service T1 tests. The test set has full T1 transmit and receive capability to perform Out-of-Service tests such as End-to-End, Loopback, and Delay tests. To support single operator loopback tests both NIU and CSU loopback commands can be sent. The test set can also emulate a NIU or CSU. For In-Service testing a monitor test mode is available. This monitor mode has dual receivers for testing two T1 lines simultaneously.

The test set can perform T1 pulse, Line code, Frame sync, Pattern sync, and BERT measurements. Additionally, all necessary alarm and error measurements are available. Measurements can be made on the full T1 or individual DS0 channels. Other features include Auto Configure, Error and Alarm Injection, and multiple Test Patterns. 10.1 Perform an end-to-end test on a T1 line During the commissioning or startup phase of a T1 circuit a several day end-to-end or hard loop test is often performed. This type of test provides the most comprehensive level of information but does require the circuit to be taken out-of-service for the duration of the test. A hard loop test requires one test set at one end of the T1 line and a hard loop at the other. An end-to-end test requires a test set at each end but enables the troubleshooter to identify the direction of the trouble. The following diagram shows the connection to perform an end-to-end test.

Test Set

RX

TX

TX

RX

Near End T1 Line Far End

Test Set


The figure below shows the DSX service panel connections required for end-to-end and hard loop testing. As mentioned above, for end-to-end testing, a test set is connected at each end of the T1 line. For hard loop testing when using only one test set connect a loop jumper between the output and input on the DSX service panel on the other end of the T1 line.

Note: For the purposes of this lab we will not actually perform an end-to-end test on a live T1 line. We will follow the steps one would take in doing an end-to-end test. There will be no T1 line involved so we will connect the test set to another T1 test set (an Electrodata T1-Lite). Configure the Electrodata T1-Lite to emulate a T1 line. Instructions: Electrodata T1-Lite Test Set Keystrokes: Electrodata T1-Lite Test

Set Connect a bantam jack cable from the Primary TX jack of the E7495A test set (on the left side) to the RX jack on the Electrodata T1-Lite. Also Connect the Primary RX jack of the E7495A test set to the TX jack on the Electrodata T1-Lite. Note: This connection treats the T1-Lite as the live T1 line. If we were actually testing a T1 line, we would connect to the DSX Service Panel such as in the figure above.

Turn on the T1-Lite [Power: ON/OFF] Set the Termination to Terminate Note: Terminate sets the input impedance of the T1-Lite to 100 Ohms and should be selected when the T1 circuit is interrupted (taken out-of-service).

[Termination: TERM/MON/BRDG]

Configure the E7495A to perform an end-to-end test on a T1 line.


Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select the T1 Analyzer option [Mode] {Backhaul} {T1 Analyzer} Restart the measurement to clear any errors from the History column

{Restart}

For a description of the T1 testing process select Get Started

{Get Started} When you have finished reading the Get Started procedure, select Back to return to the T1 mode. {Back}

Select the Hard Loop / End-End Full T1 Bit Error Rate Test (BERT)

{Hard Loop / End-End} {Full T1 BERT}

Select the Primary Auto Configuration to allow the test set to align the setup choices to the properties of the incoming T1 signal (from the T1-Lite).

{Auto Config} {Start Primary Auto Config} {Back}

Enter the Setup menu to select the various parameters for end-to-end testing Note: Most of the default settings will be used. The purpose of this procedure is to demonstrate the many setup options available on the test set.

{Setup}

Set the RX Input to Terminate Note: Terminate sets the input impedance of the test set to 100 Ohms and should be selected when the T1 circuit is interrupted (taken out-of-service).

{RX Input} {Terminate}

Set the line code to B8ZS Note: B8ZS (Bipolar 8 Zero Substitution) replaces runs of 8 zeroes with a special code that is not compatible with AMI (Alternate Mark Inversion).

{Line Code} {B8ZS}

Set the Framing pattern to ESF (Extended Super Framing) Note: ESF is a 24-frame structure accomplished by sending a unique pattern on the 193rd (framing) bit. In this mode the frame bits are used to transmit a CRC and carry information to accommodate alarms and control.

{Framing} {ESF}

Set the Pattern to QRSS {Pattern} {QRSS} Set the Transmit Clock to Internal Note: When Internal is selected, the transmit clock is derived within the test set and is independent of the incoming signal.

{TX Clock} {Internal}

Set the Transmit Line Build Out level to 0 dB Note: 0 dB is a typical level found on the T1 line at the customer’s demarcation point. (0dB LBO = 0 dBdsx = 6 Vpp)

{TX LBO} {0 dB}

Disable the frame slip measurement {More 1 of 2} {Slip Ref} {None} Display the T1 parameters {Display}


The screen displays parameters for three main categories: Status, Alarms, and Results. A �Pass� state is displayed in green and a �Fail� state is displayed in red (either LED or text). The top portion of the screen displays Status indicators: T1 Pulses, B8ZS, Frame Sync, Pattern Sync, Alarms and Errors. Currently only the Primary transmit and receive is being used. The test set can also measure a Secondary T1 line and display the Secondary Status indicators either separately or simultaneously with the Primary Status indicators. The lower portion of the screen displays the Alarms and Results. The Alarms consist of Signal Loss, Frame Loss, Excess Zeros, All Ones (AIS), Yellow Alarm, and Idle (CDI). The Results Summary consists of: BPV, Frame, CRC, Pattern, Recv Level (in dBdsx and in Vpp), Frequency, and Elapsed Time. Let�s inject a Bipolar Violation (BPV) error using the T1-Lite and view the results on the E7495A test set. Instructions: Electrodata T1-Lite Test Set Keystrokes: Electrodata T1-Lite Test

Set Restart the T1 measurements to clear the history errors.

[Restart]

Inject a BPV error [Setup] Using the Down arrow highlight “Error Insert”. Hold down the [Edit] button and use the Up arrow to highlight “BPV”. [Restart] [Error]


Notice the Errors Status indicator displays �Detected� and then in the next clock cycle displays �Were Detected�. Also notice the BPV Results LEDs turned red indicating an error. The left column displays current Results and the right column displays History. The left column LED turns back to gray in the next clock cycle. If you like, inject more errors and view the Status indicator changes. Record the Recv Level (in dBdsx):_________ (in Vpp):_________ and Frequency:___________ Let�s find out how many BPV Errors occurred and for how long. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select the Primary BPV and Frame Errors Results

{Results} Using the RPG dial highlight the “Primary BPV and Frame Errors” on the Results List. {Select}

Record the BPV Errors:____________ BPV Error Rate:_______________________ and the BPV Errd Secs:________________ Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Return to the Results Summary {Results}

Using the RPG dial highlight the “Primary Summary” on the Results List. {Select}

Let�s now turn off the T1-Lite to simulate a loss of signal.


Instructions: Electrodata T1-Lite Test Set Keystrokes: Electrodata T1-Lite Test Set

Turn off the power [Power: ON/OFF] Notice the change in the LEDs of the Status, Alarms, and Results. Record the Recv Level (in dBdsx):_________ (in Vpp):_________ and Frequency:___________ Let�s now turn the power of the T1-Lite back on. Instructions: Electrodata T1-Lite Test Set Keystrokes: Electrodata T1-Lite Test

Set Turn on the power [Power: ON/OFF] Which Alarms and Results indicate an error occurred in the past (when there was no signal)? What is the value of knowing which errors occurred in the past? The ability to view the history of errors can prove vital in troubleshooting and isolating T1 line errors. Using the test set you can select the specific results categories to drill down and find more detailed information concerning the errors that have occurred. Let�s find out how many BPV Errors occurred and for how long. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select the Primary Performance Results {Results}

Using the RPG dial highlight the “Primary Performance” on the Results List. {Select}

Record the Error Free Secs:____________ and percentage:_______________________ the Errored Secs:________________ and percentage:____________________________ the Available Secs:_________________ and percentage:_________________________ and the Unavailable Secs____________________ and percentage:_________________ Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Return to the Results Summary {Results}

Using the RPG dial highlight the Primary Summary on the Results List. {Select}


10.2 Perform a loopback CSU test on a T1 line When the far-end of a T1 circuit is in a remote location and trouble is suspected, it is possible to place the equipment at the far-end into loopback by sending a special code designated for this purpose. If the T1 circuit is leased, then the wireless technician is often limited to looping only the CSU, as NIU loop codes are usually blocked at the central office. The loop code can be sent either in-band or on the ESF datalink channel by the test set to the far-end equipment. The first method, in-band, replaces the bits in the T1 traffic channels with the unique loop code. The remote equipment must see this code for 5 seconds before it will respond in order to minimize the potential that patterns in live data will falsify this request. The downside of this technique is that all devices in the transmit path see this code and any may respond. This could lead to a confusing situation if a T1 route consists of multiple hops, each with its own CSU pair. If the far end has a hard loop, then the loop code could come back to the near and inadvertently place that CSU into loopback. The test set does monitor for a pre-existing loop and will notify the user when remote loopback is attempted using an in-band loop code. Another method is available if the circuit is provisioned for Extended Super Frame (ESF). This method, ESF datalink, sends the loop code on the ESF data link bits. This method is not subject to or prone to false information and, therefore, responds very rapidly. This is the default mode of the test set. The following diagram shows the connections to perform Loopback CSU/NIU testing. Configure the Electrodata T1-Lite to emulate a Channel Service Unit (CSU). Instructions: Electrodata T1-Lite Test Set Keystrokes: Electrodata T1-Lite Test

Set Enter the Setup menu [Setup]

Using the Down arrow highlight “Loop Code Type”

Select NIU/CSU Loop Code Type Hold down the [Edit] button and use the down arrow to highlight” NIU/CSU.”

RX TX

TX

RX

Near End T1 Line Far End

Test Set CSU/NIU


Select the CSU Loop Code Using the Down arrow highlight “Loop Code”. Hold down the [Edit] button and use the Down arrow to highlight “CSU”.

Select the �In-Band� ESF Loop Code Using the Down arrow highlight “ESF Loop Code”. Hold down the [Edit] button and use the Down arrow to highlight “In-Band”.

Enable the CSU Emulate mode Using the Down arrow highlight “NIU/CSU Emulate”. Hold down the [Edit] button and use the Down arrow to highlight “Enabled”.

The T1-Lite test set is now ready to respond to loopback commands from the E7495A test set. Configure the E7495A test set to send loopback commands to the T1-Lite test set. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select the Loopback CSU/NIU Full T1 BERT Mode

{Get Started/Test Mode} {Loopback CSU/NIU} {CSU Full T1 BERT}

Select the In-band loopback method {Setup} {More 1 of 2} {ESF Loopcode} {In-band}

Disable the frame slip measurement {Slip Ref} {None} �Loop Up� the Far End CSU (In our case the T1-Lite)

{Control} {Send Loop Up}

Notice in the top right corner of the screen the statement �Sending Loop Up�. Once the loop up process is complete the statement changes to �Loop Up completed�. Assuming a �loop up� command has already been sent to the far end CSU, what will happen if we attempt to send another �loop up� command to the far end CSU? Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Send another �loop up� command to the far end CSU

{Send Loop Up}

The E7495A test set displays a �Pre-existing Loop� condition at the top right corner of the screen. The T1-Lite test set is currently set to expect a QRSS pattern. Configure the E7495A test set to transmit a �2 in 8� pattern. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select the �2 in 8� pattern {Pattern}

Using the RPG dial highlight the “2 in 8” pattern. {Select}


Notice in the top left corner of the screen under �Test Mode: Loopback CSU Full T1 BERT� the setup indicators �In-band, B8ZS, ESF, 2 in 8�. Instructions: Electrodata T1-Lite Test Set Keystrokes: Electrodata T1-Lite Test

Set Clear the past errors [Restart] Now that the E7495A is transmitting the �2 in 8� pattern, which T1 parameter(s) are failing on the T1-Lite (which green LEDs are off)? Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select the �All 0�s� pattern {Pattern}

Using the RPG dial highlight the “All 0’s” pattern. {Select}

Instructions: Electrodata T1-Lite Test Set Keystrokes: Electrodata T1-Lite Test

Set Clear the past errors [Restart] Now that the E7495A is transmitting the �All 0�s� pattern, which T1 parameter(s) are failing on the T1-Lite? Why did the different patterns transmitted by the E7495A test set cause different T1 parameters to fail? When transmitting the �2 in 8� pattern, a B8ZS is never transmitted. When transmitting �All 0�s�, a B8ZS occurs. The �All 0�s� pattern is often selected to verify B8ZS provisioning. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select the �QRSS� pattern {Pattern}

Using the RPG dial highlight the “QRSS” pattern. {Select}

10.3 Perform a delay measurement on a T1 line Quality of service metrics such as echo or failure rates may depend on the electrical distance of a T1 circuit. The E7495A test set has the capability to measure the round trip delay of a T1 circuit and estimate the distance. The exact numbers depend on knowing precisely what the propagation


delay of the various transmission mediums are for copper or fiber. The measurement takes into account typical propagation delays and displays the information accordingly. The most accurate results will be obtained when the far end is hard-looped with a patch cable or loop plug. It is possible to measure delay when in loopback mode. Configure the E7495A to measure the delay of the T1 line while in loopback mode. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select Delay mode {Get Started/Test Mode} {Delay} {Full T1} Record the Round Trip Delay (in µs):_________________________ Record the One Way Delay (in kilofeet):________________ or (in mi):________________ How does the One Way Delay (in kilofeet or miles) compare to the length of the bantam jack cables? Why is there a difference between the displayed delay distance and the actual length of the bantam jack cables? The signal processing devices in the T1-Lite test set added delay and affected the measurement accuracy. When making delay measurements on T1 lines, you must consider the signal processing delays of the various instruments the signal will encounter along the T1 path. Now let�s send a �loop down� command to the CSU (T1-Lite). Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set {Loopback CSU} {CSU Full T1 BERT} �Loop Down� the Far End CSU (In our case the T1-Lite)

{Control} {Send Loop Down}

Notice the �Loop Down Completed� statement in the upper right corner of the screen. 10.4 Monitor a T1 line T1 circuits carry a significant amount of traffic and often cannot be take out-of-service for testing. Fortunately there is a way to �patch into� a live circuit and observe metrics that provide insight into the performance of that circuit. When a monitor jack is available it is possible to �jack into� a live circuit without interrupting traffic. A resistor couples a portion of the actual T1 circuit inside the jack panel from the live circuit to the monitor jack. When the test set Rx Input is set to �Monitor� it provides a terminated connection to the monitor jack and enables an amplifier within the test set to compensate for the reduced level available at the monitor jack. This enables the test set to properly detect and display the level on the actual circuit as if it were connected directly to that circuit.


The figure below shows the connections required for monitoring a T1 line.

Configure the E7495A to monitor the T1 line. Instructions: E7495A BS Test Set Keystrokes: E7495A BS Test Set Select Monitor mode {Get Started/Test Mode} {Monitor}

{Monitor Full T1} Set the RX Input to Monitor {Setup} {RX Input} {Monitor} Display the T1 parameters {Display} Instructions: Electrodata T1-Lite Test Set Keystrokes: Electrodata T1-Lite Test

Set Disable the CSU Emulate mode [Setup]

Using the Down arrow highlight “NIU/CSU Emulate”. Hold down the [Edit] button and use the Down


arrow to highlight “Disabled”. Inject a BPV error [Restart] [Error] Inject a Bit error [Setup]

Using the Down arrow highlight “Error Insert”. Hold down the [Edit] button and use the Up arrow to highlight “Bit”. [Restart] [Error]

Inject a Frame error [Setup] Using the Down arrow highlight “Error Insert”. Hold down the [Edit] button and use the Up arrow to highlight “Frame”. [Restart] [Error]

Inject a CRC error [Setup] Using the Down arrow highlight “Error Insert”. Hold down the [Edit] button and use the Up arrow to highlight “CRC”. [Restart] [Error]

Notice the History of errors in the Results Summary.

This completes the lab exercises. Power off the instruments and remove the batteries from the E7495 Base Station Test set for long-term storage.


Instructions: E7495X BS Test Set Keystrokes: E7495X BS Test Set Completely turn off the E7495X BS Test Set Press the large round [White Power Button] for

at least 5 seconds. Pressing the button momentarily or for less than several seconds causes the test set to go to Sleep (Standby) mode.

Remove batteries from battery compartment to prevent discharge during shipment or long-term storage.

Open battery door on bottom of unit by rotating ring-clip fastener until door opens. Remove batteries by pulling firmly on white strip. (Note power level indicators on batteries) Close door by pressing firmly shut and rotating ring-clip fastener back into place.


Summary

In this lab exercise we performed many of the measurements required to sufficiently maintain wireless networks � specifically the base station cell site using the E7495x Base Station Test Set. We measured the insertion loss of a cable and an attenuator, measured the return loss and distance to fault of an antenna and its feedline, viewed the spectrum of a cdma2000 signal, performed GSM channel scanner measurements, measured the average power of a GSM signal, verified proper cdma2000 transmitter performance, made cdma2000 over air measurements, and measured T1 line performance. Finally, we explored the W-CDMA Tx analysis and Adjacent Channel Power measurement capabilities of the instrument. Hopefully, these exercises have increased your proficiency and understanding of making base stations measurements using the E7495x Base Station Test Set.


Appendix A – Effects of Interference on Estimated Rho While Making CDMA Over Air Measurements

Estimated Rho is a measure of CDMA waveform quality and is typically made at the transmitter output. In an over-the-air scenario the system measures the waveform quality of the received signal which has been subjected to the effects of interference and multipath. As interference and multipath raise the noise floor of the code domain power measurement, the maximum expected reading of estimated Rho decreases. As pilot dominance decreases and/or multipath power increases, the maximum reading you should expect from estimated Rho decreases. Table 1 below shows the degradation of estimated Rho expected for various values of pilot dominance. This table assumes the ratio of the traffic power received from the two sectors (strongest and second strongest) is approximately the same as the ratio of the pilots (pilot dominance). If the traffic power from the sector with the strongest Pilot is much higher, the degradation will be slightly less. If the traffic power from the second sector is much higher, the degradation will be slightly more. Table 1. Estimated Rho degradation due to Pilot Dominance.

Pilot Dominance Est Rho Degradation (X)

5 dB 0.25

6 dB 0.21

7 dB 0.17

8 dB 0.14

9 dB 0.12

10 dB 0.10

11 dB 0.08

12 dB 0.06

13 dB 0.05

14 dB 0.04

15 dB 0.03

16 dB 0.025

17 dB 0.02


Table 2. Estimated Rho degradation due to Multipath Power.

Multipath Power Est Rho Degradation (Y)

0.75 dB 0.17

0.70 dB 0.16

0.65 dB 0.15

0.60 dB 0.14

0.55 dB 0.135

0.50 dB 0.13

0.45 dB 0.12

0.40 dB 0.10

0.35 dB 0.09

0.30 dB 0.08

0.25 dB 0.06

0.20 dB 0.05

0.15 dB 0.04

0.10 dB 0.03 When measuring estimated Rho over-the-air, the degradation due to an interfering sector and multipath echoes must be considered when interpreting the results. The maximum estimated Rho you should expect to measure is calculated as

Maximum estimated Rho = 1.0 - X - Y where, X is the degradation due to pilot dominance as shown in Table 1, and Y is the degradation due to multipath echoes - see Table 2. Example calculation:

Pilot dominance = 14 dB => X = 0.04 Multipath power = 0.4 dB => Y = 0.10 Maximum estimated Rho = 1.0 - 0.06 - 0.10 = 0.84

In this case, measurements of estimated Rho substantially less than 0.84 indicate poor waveform quality from the sector under test, or possible interference from outside of the CDMA system.


Appendix B – T1 Information

Status Indicators

• T1 Pulses � The test set is receiving pulses at the receive jack. Frame pulses alone are not sufficient to activate this indicator. There must be pulses present in the payload field.

• B8ZS � A B8ZS pulse pattern was detected on the incoming signal at the receive jack. Note that only certain patterns transmit B8ZS pulse patterns. The pattern must contain at least 8 consecutive zeroes before a B8ZS pattern is sent. The QRSS pattern will generate B8ZS while an idle T1 circuit transmitting all 1�s will not.

• Frame Sync � A frame sync pattern matches the one specified in the setup screen on the test set.

• Pattern Sync � The received pattern matches the one specified in the setup screen on the test set

Alarm Indicators

• Signal Loss � The test set encountered the absence of 192 or more consecutive pulses. A frame pulse may or may not be present

• Frame Loss � The test set encountered an unexpected frame pattern. The frame pattern did not match the one selected in �Setup�

• Excess Zeros � The test set encountered the absence at least 16 consecutive pulses in AMI mode or the absence of at least 8 consecutive pulses in B8ZS mode.

• All Ones � The test set encountered an unframed, all 1s pattern ( a constant contiguous stream of 1s). This pattern is also known as an Alarm Indication Signal (AIS), keep-alive signal, or blue alarm. Blue alarms are generated by faulty transmission equipment such a T3 to T1 multiplexer.

• Yellow Alarm � A Remote Alarm Indication (RAI) signal pattern was received. This is normally sent by the far end interface equipment (CSU) in response to receiving a blue alarm on its network side. In D4 framing mode a yellow alarm is created at the far end by setting bit 2 to 0 for 255 consecutive frames. In ESF, a pattern of eight 0s and eight 1s is repeated 16 times to indicate a yellow alarm.

• Idle (CDI) A Customer Disconnect Indication signal was received from the far end interface unit indicating that the customer is no longer supplying a signal. A CDI signal is an in-band pattern 0001 0100. Eight ones followed by eight zeros interrupted each second for 100 ms with LAPD Idle code (01111110) will be sent in the ESF Facility Data Link (ESF FDL).

Results Indicators

• BPV � A momentary indicator that responds when a bipolar violation occurs on the incoming signal applied to the Receive jack. B8ZS codes are not considered a BPV and will not activate this indicator when the test set is set to AMI mode.

• Frame � A momentary indicator that responds when the test set encountered a disruption of the incoming frame pattern.

• Pattern � A momentary indicator that responds to a disruption of the incoming pattern..


• CRC � A momentary indicator that respond to a disruption of the incoming CRC. This indicator is applicable in only ESF mode.

Results Measurement Fields: Recv Level: The voltage level of the signal measured at the Rx jack. ( 0 dBdsx = 6 Vpp)

Frequency: The frequency of the signal measured at the Rx jack. The T1 Pulses indicator must be active for this measurement to be displayed.

Elapsed Time: Indicates the amount of elapsed time since the last measurement reset.

BPV Errors: A tally of the number of BPV errors since the last measurement reset.

BPV Error Rate: The percent ratio of BPV errors to total bits transmitted since the last measurement reset.

BPV Errd Secs: The number of one second intervals since the last measurement reset that contained BPV errors.

Frame Errors: A tally of the number of Frame errors since the last measurement reset.

Frame Error Rate: The percent ratio of frame errors to total bits transmitted since the last measurement reset.

Frame Errd Secs: A tally of the number of one-second intervals since the last measurement reset that contained frame errors.

Signal Loss A tally of the number of one-second intervals since the last measurement reset that contained signal errors.

Frame Sync Loss: A tally of the number of one-second intervals since the last measurement reset that contained frame sync loss.

Excess Zeros: A tally of the number of one-second intervals since the last measurement reset that contained excess zeros.

All 1’s: A tally of the number of one-second intervals since the last measurement reset that contained the AIS pattern.


Yellow Alarm A tally of the number of one-second intervals since the last measurement reset that contained the yellow alarm pattern.

Error Free Seconds: A tally of the number of one-second intervals that were error free since the last measurement reset.

Errored Seconds: A tally of the number of one-second intervals since the last measurement reset that contained errors such as BPVs and frame errors.

Severe Errored Seconds: A tally of the number of one-second intervals since the last measurement reset that were severely errored.

Available Seconds: A tally of the number of one-second intervals since the last measurement reset that were available for service.

Unavailable Seconds: A tally of the number of one-second intervals since the last measurement reset that were unavailable for service.

Degraded Minutes: A tally of the number of one-second intervals since the last measurement reset that were degraded.

Slip Rate: The percent ratio of frames cycle slips of the incoming signal relative to the slip reference choice on the setup menu � since the last measurement reset.

Peak + Wander: The peak amount of positive wander, measured in bit intervals, since the last measurement reset. Each peak wander interval of 193 qualifies as a frame slip.

Peak – Wander: The peak amount of negative wander, measured in bit intervals, since the last measurement reset. Each peak wander interval of 193 qualifies as a frame slip.

+Frame Slips: A tally of the number of positive frame slips that occurred since the last measurement reset.

-Frame Slips: A tally of the number of positive frame slips that occurred since the last measurement reset.

Bit Errors: A tally of the number of bit errors that occurred since the last measurement reset.


Bit Error Rate: The percent ratio of bit errors to total bits transmitted since the last measurement reset.

Pattern Sync Loss: A tally of the number of times the pattern detector lost synchronization since the last measurement reset.

Test Data Rate: The measured data rate of the bit stream. Setup Choice Selection Descriptions: RX Input: Configures the RX Input properties on the test set. Select Terminate, Monitor, or Bridge. The Primary and Secondary inputs are both affected by this setting. • Terminate sets the input impedance to 100 Ohms and should be selected when the T1 circuit

is interrupted. • Monitor sets the input impedance to 100 Ohms, inserts 20 dB gain and should be selected

when connected to a �Monitor� jack. Bridge sets the input impedance >1000 Ohms and should be selected when bridging on to a T1 circuit. Line Code: Configures the test set to transmit and expect to receive a line code that is compatible with the circuit�s provisioning.

• AMI � Alternate Mark Inversion is a traditional line code that transmits alternating polarity, half bit-width voltage pulse to indicate the presence of a �1� data bit and no signal to indicate the presence of a �0� bit.

• B8ZS � Bipolar 8 Zero Substitution replaces runs of 8 zeroes with a special code that is not compatible with AMI. It allows greater flexibility of data patters by enhancing repeater synchronization by increasing pulse density thereby providing greater throughput.

Configures the test set to transmit and expect to receive a particular framing pattern that is compatible with the circuit�s provisioning. Framing: • Unframed � The 193rd (framing) bit is set to 1. • D3/D4 � A 12 frame structure accomplished by sending a unique pattern on the 193rd

(framing) bit. ESF � A 24 frame structure accomplished by sending a unique pattern on the 193rd (framing) bit. In this mode the frame bits are used to transmit a CRC and carry information to accommodate alarms and control. Pattern: Configures the test set to transmit and expect to receive a particular test pattern

• 1:7 � An eight-bit pattern that contains a single one. Used to test clock recovery. • 2 in 8 � An eight bit pattern with two ones and a maximum of four consecutive zeroes.

B8ZS is never sent.


• 3 in 24 � A twenty-four bit-pattern containing 3 ones with the longest length of consecutive zeroes constrained to fifteen. It has a ones density of 12.5% and is used to check clock recovery.

• All 1�s � A pattern that causes line drivers to consume the maximum amount of current. If framing is set to �Unframed� the resulting pattern is equivalent to a �Blue Alarm� or �Alarm Indication Signal� or AIS.

• All 0�s � A pattern that is often selected to verify B8ZS provisioning. • QRSS � A pseudorandom pattern that simulates live traffic on a circuit. It is a very

common test pattern • T1�DALY � A pattern that changes rapidly between high and low density. This pattern

is used to stress ALBO, equalizer and timing recovery circuits. • 55 Octet � Similar to the T1-DALY pattern except that it contains runs of fifteen

consecutive zeroes that violate ones density requirements if sent unframed. • 2E15-1 � A pseudorandom pattern based on a 15 bit shift register. • 2E20-1 � A pseudorandom pattern based on a 15 bit shift register.

AutoConfig: Selecting Auto Config causes the test set to analyze the incoming T1 signal and align the setup choices to that signal. If the incoming data pattern is not recognized then �NA Live Data� is displayed and the pattern selected on the setup screen will remain unchanged. If B8ZS codes are detected then this condition will be indicated and the line code parameter will be set accordingly. If setup was configured for B8ZS prior to selecting �Auto Config� and the pattern detected does not have sufficient zeros density to warrant B8ZS then �NA� will be displayed and the line code choice in the setup screen will remain unchanged. Finally, the framing format is detected, displayed and selection changed accordingly on the setup screen. TX Clock: Configures the test set to use one of the following methods to derive the transmit clock frequency. Internal � The transmit clock is derived locally and independent of any incoming signals. This is useful when the device or line under test is configured to synchronize on the incoming signal. In this case the return clock frequency of the return signal should match the transmit clock frequency of the test set. • Primary RX � The transmit clock frequency is derived from the signal received at the Primary

RX jack on the test set. Secondary RX � The transmit clock frequency is derived from the signal received at the Secondary RX jack on the test set. TX LBO: TX Line Build Out [TX LBO] sets the TX level and pulse shape to simulate the signal conditions that would be encountered at the end of a distant transmission cable. This is useful for testing equipment suspect of having trouble receiving signals found in typical applications.

• 0dB LBO = 0 dBdsx = 6 Vpp • -7.5 dB LBO = -7.5 dBdsx = 2.53 Vpp • -15 dB LBO = -15 dBdsx = 1.07 Vpp

Channel:


Specifies the channel to be utilized when a test mode is selected to operate on a channel as opposed to full T1 Fill Data: Specifies the souce of data in the slot numbers other than the on chosen the channel field. This is applicable for only channel tests. ESF Loop Code: This choice specifies how the loopcode will be sent to the far end and in Loopback Mode and which type of code the test set will respond to in emulate mode.

• In-band: Loop codes replace the live data. • Datalink: Loop codes are sent on the ESF datalink channel.

Slip Reference: This choice determines which signal that test set will compare the incoming signal with during the frame slip measurement.

• None: Disables the frame slip measurement. • Internal: Compares the frame of the signal at the Primary Rx jack with the internal

reference. • Second Rx: Compares the frame of the signal at the Primary Rx jack with that of the

signal on the Secondary Rx jack. Second TX: Select the source of data on the Secondary Tx jack.

• AIS: The signal present at the Secondary Tx jack will be unframed all 1�s • Second Rx: The source of the signal at the Secondary Tx jack will be from the

Secondary Rx jack. • Primary Rx: The source of the signal at the Secondary Tx jack will be from the

Secondary Rx jack. Terminology:

CRC: To an observer, the data on a live T1 Circuit appear to be random. Fortunately there is a way to perform limited testing when the circuit is provisioned for Extended Super Frame (ESF) format. A portion of the frame bits are reserved for a Cyclic Redundancy Checksum (CRC) sequence that can be monitored for performance. Simply stated, the CRC bits are calculated on the transmit end and inserted as a pattern on the frame bit. The CRC pattern depends on the pattern of other bits transmitted by the T1 Circuit. The receiving end also computes this pattern and compares it with the CRC that was computed and sent by the transmitting end. Since both ends use the same rules for computing the pattern, the CRC bits will be identical when all the bits involved in the


computation agree. The CRC check provides good insight into the end-to-end integrity of the T1 Circuit and should be used in conjunction with other tests that can help determine what the cause of the CRC failure might be.

BPV: The electrical signals on a properly functioning T1 circuit conform to the specification set forth in the standards. The standards specify that the presence of a voltage indicates a data �1� and the absence of a voltage represents a data �0�. Each occurrence of a data one produces a voltage for half a bit interval that is the opposite polarity of the previous bit, hence the name Alternate Mark Inversion (AMI). The alternating nature of the signal ensures that the average DC voltage is zero, allowing it be transformer coupled. Transformer coupling ensures a high degree of common mode rejection to the equipment that processes T1 signals. Bipolar 8 Zero Substitution (B8ZS) is an exception to AMI that replaces runs of 8 consecutive zeroes with a special code that violates the AMI rules. It allows greater flexibility of data patters by enhancing repeater synchronization by increasing pulse density thereby providing greater throughput. When the electrical signal does not adhere to the alternating nature of the waveform specification a BiPolar Violation (BPV) has occurred. This can happen for a number of reasons, many of which are outside the control of the wireless technician. One cause may be from electrical noise radiating from florescent lamps, motors, or spark plug ignition circuits coupling into the copper lines that carry T1 signals. Shielded cable is often chosen for T1 circuits to minimize electrical interference. This shield must be grounded to be effective. When the cable is spliced or terminated the shield on both cables should be connected together. Often the transmit and receive signals are routed in separate cable bundles. The receive signal is often much weaker that the transmit signal. Cross talk in the cable pairs can cause the transmit signal to appear on the receive pair and interfere with the low-level receive signal.

Frame: Pulses streaming in a T1 circuit would be meaningless if there were no way to organize them in a meaningful structure. In T1, bits are organized into 192 bit frames with an associated single frame bit for a total of 193 bits. The frame bit pattern has unique characteristics about it that allow the receiving end to recognize it synchronize to it. D3/D4 framing patterns have the ability to identify a super frame of 12 sub-frames. Extended Super Fame (ESF) has the ability to identify a super frame of 24 sub-frames and include a data link channel and Cyclic Redundancy Checksum (CRC) check bits.

Patterns: Many test patterns are available to �stress� the circuit in a unique way or to gain maximum insight into a particular problem. Much has been written to guide the troubleshooter to select the proper pattern. Below is a summary of the qualities of the patterns available in the test set.


• 1:7 � An eight-bit pattern that contains a single one. Used to test clock recovery. • 2 in 8 � An eight bit pattern with two ones and a maximum of four consecutive zeroes.

B8ZS is never sent. • 3 in 24 � A twenty-four bit-pattern containing 3 ones with the longest length of

consecutive zeroes constrained to fifteen. It has a ones density of 12.5% and is used to check clock recovery.

• All 1�s � A pattern that causes line drivers to consume the maximum amount of current. If framing is set to �Unframed� the resulting pattern is equivalent to a �Blue Alarm� or �Alarm Indication Signal� or AIS.

• All 0�s � A pattern that is often selected to verify B8ZS provisioning. • QRSS � A pseudorandom pattern that simulates live traffic on a circuit. It is a very

common test pattern • T1�DALY � A pattern that changes rapidly between high and low density. This pattern

is used to stress ALBO, equalizer and timing recovery circuits. • 55 Octet � Similar to the T1-DALY pattern except that it contains runs of fifteen

consecutive zeroes that violate ones density requirements if sent unframed. • 2E15-1 � A pseudorandom pattern based on a 15 bit shift register. • 2E20-1 � A pseudorandom pattern based on a 15 bit shift register. • 2E23-1 � A pseudorandom pattern based on a 15 bit shift register. • Alternating Ones and Zeroes � A pattern that alternates between ones and zeroes. • 2E20-1 � A pseudorandom pattern based on a 15 bit shift register. • 2E23-1 � A pseudorandom pattern based on a 15 bit shift register. • Alternating Ones and Zeroes � A pattern that alternates between ones and zeroes.

Auto Config: Selecting Auto Config causes the test set to analyze the incoming T1 signal and align the setup choices to that signal. If the incoming data pattern is not recognized then �NA Live Data� is displayed and the pattern selected on the setup screen will remain unchanged. If B8ZS codes are detected then this condition will be indicated and the line code parameter will be set accordingly. If setup was configured for B8ZS prior to selecting �Auto Config� and the pattern detected does not have sufficient zeros density to warrant B8ZS then �NA� will be displayed and the line code choice in the setup screen will remain unchanged. Finally, the framing format is detected, displayed and selection changed accordingly on the setup screen.

using the e7495a-b to make transmitter measurements

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