sweep equipment application and configuration .application note: sweep equipment application and
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Sweep Equipment Application and Configuration
This application note is organized into two primary sections after the Overview of Sweepintroduction. The Forward Sweep section beginning on page 3 includes configuration detail, Tipsand Field Meter Settings chart followed by Reverse Sweep with similar aids starting on page 13.
ApplicationForward and Reverse Sweep and Balance using JDSU Stealth Sweep technology incorporated in SDAnetwork equipment and SDA-5000 and DSAM-6000 field meters.
Summary of EquipmentDSAM-6000 and SDA-5000 field meters with Stealth Sweep technology options enabled can performeither forward, reverse or both sweep operations, depending on options installed and configurations atthe meter and at the headend SDA network units.
SDA-5500 Stealth Sweep Transceiver is located in the headend or hub site. It transmits sweep points onthe forward path and/or uses broadcast program carriers, either analog or digital, as reference points,thus minimizing the use of active sweep points. If so configured, it can also manage a single field meterfor sweeping the return from a field location.
SDA-5510 Return Sweep Manager is located in the headend or hub site. It is strictly used for managingmultiple field meters for simultaneous return sweep operations. Up to 10 meters can sweep the returnat the same time.
Note: This application note describes the setup and configuration of SDA equipment manufactured as of2001. Equipment prior to year 2001 has minor user interface differences. Most prominent is the Functionkey. Prior to 2001 the Function key was green instead of blue.
Overview of SweepThe DSAM-6000 and SDA-5000 field meters sweep display shows the difference (delta) in level fromthe headend to the field meter or vice versa. The goal is to measure the frequency response of the cablesystem distribution network. This is done by injecting active sweep points (momentary narrow testcarriers) over a range of frequencies at the input of the hybrid fiber coax (HFC) distribution system.The level of each sweep point is measured at both the input and the output of the system. At thereceiving end (output), the two values are compared and the difference is displayed on the field meter,thereby emphasizing any deviation caused by the network. As an alternative to active test sweep pointsinjected around a channel, the actual broadcast video carrier can be used as a reference carrier for thatfrequency. An optimized sweep plan will include both active sweep points, representing unusedfrequency bands within the networks spectrum, as well as reference carriers. This exclusive StealthSweep technology is patented by JDSU and minimizes any possibility of service interference.
Both directions of the network can be swept. Forward sweep is accomplished with the SDA-5500Stealth Sweep Transceiver and measurement system in the headend or hub site. It transmits andmeasures active sweep points as well as measures reference carriers. Multiple DSAM-6000 or SDA-5000field meters can be used at the same time with a common SDA-5500. Typically the headend technicianor network engineer is responsible for an accurate forward sweep plan within the SDA-5500 transceiver.
Reverse sweep is accomplished in a similar manner except that only active sweep points are transmittedand measured by the field meter and the SDA-5500 receives and measures the sweep points at theheadend or hub site. Only a single field user at a time can perform reverse sweep with the SDA-5500.Larger networks typically will use a SDA-5510 Stealth Reverse Sweep Manager to handle only reversesweep for multiple field users and configure the SDA-5500 for only forward sweep requirements.
2Application Note: Sweep Equipment Application and Configuration
Splitter Headend or Hub Site Distribution Plant
FORWARD SWEEPMeter receives sweep pulses and reference levels transmitted from headend or hub site and displays difference levels (delta).
RETURN SWEEPMeter generated sweep pulses transmitted from field and received in headend or hub site.
RETURN SWEEPHeadend or hub site transmits received sweep pulse levels back to originating field meter for display of difference levels (delta).
The DSAM-6000 and the SDA-5000 perform both forward and reverse sweep functions.*
3Application Note: Sweep Equipment Application and Configuration
Forward SweepStep-by-Step Headend Set-up for Forward Sweep (see diagram below)A diplex filter is used to combine reverse signals into the rack mounted SDA-5500 instead of a splitteror DC-12 due to isolation issues. Also the return fiber receiver is likely to be 5-200 MHz. This couldcause jitter on the forward sweep if not set-up properly. Because the SDA Stealth Sweep Transceivermust see itself, be mindful of what is in this sample loop, such as launch amps, filters, etc; it couldcause problems.
Note: Be sure input levels are between 4 and 12 dBmV. The recommended level is 6 dBmV 2. If levels are toohigh, channels may be enabled that are present. Levels too low will leave channels disabled that otherwiseshould be present. The recommended input for reverse RF into the SDA-5500 Transceiver and SDA-5510Return Sweep Manager is 0 dBmV 2. It may work between 10 dBmV, but it depends on the aggregatenoise floor.
Build Channel Plan (Configure > Channel Plan)If a channel plan has already been made, choose it from the list under Select Channel Plan.
Note: Configure mode can be accessed through the Navigator mode, or by pressing the green function keyfollowed by the number 3 key. Channel plans and files names are limited to 15 characters.
1. Signal TypeNTSC for North America, PAL or SECAM for Europe
2. Build Channel PlanThe forward channel plan should be set up on the SDA-5500 or StealthWare PC software.a.Enter Plan Nameb. Type of Plan (NCTA is common in North America, but could be HRC or IRC)c.Stop Frequency (be sure to press enter then ok)
3. Edit Channel Parametersa.Enable or disable channels appropriately. Default channel type will be analog TV.b. Enter tilt channels, sweep channels and/or scrambled channelsc.Enter the type of channel
(Single, TV, Dual, Digital, QAM Digital Stream, or Sweep Insertion Point)
TipsWhen making labels, the up and down diamond keys may be used to access special symbols (i.e., @, $,etc.). To get to a certain channel more quickly than scrolling, go to the Level mode, type in the channelnumber, then go back to Edit Channel Plan or press the green function key followed by the number 4key. TV is for regular, analog television signals; Single designation is used for continuous wave (CW)carriers; Dual is for NICAM not Secondary Audio Programming (SAP); QAM Digital Stream is for 64or 256-QAM carrier designation for the QAM option on SDA field meters; and Digital is for regulardigital haystacks regardless of modulation type. Do not delete unused channels until sweep pointsare made. If all disabled channels are deleted, no sweep points will be made.
Build Sweep Points on SDA-5500 (Configure > Channel Plan > Build Sweep Points)This is an option on the SDA-5500 only. Sweep insertion points are for vacant bandwidth and channelswhich are disabled to allow sweeping of the entire spectrum. The default is channel 2 to 1 GHz for thesweep, but sweep points can be inserted anywhere between 5 MHz and 1 GHz. Sweep insertion pointsare not automatically inserted in the FM band. You must do this manually if required. Build insertionpoints for disabled channels; 2 points per channel slot is the default, 3 is the max, 1 is sufficient in mostcases. Sweep points are approximately 2.8 ms in duration and approximately 100 kHz wide. Ensure thatno sweep insertion points are built within 6 MHz of either side of the AGC frequency as this may causeproblems with the AGC circuitry in certain amplifiers.
SDA-5500 Sweep Transmitter (Configure > Sweep Transceiver)Sweep Mode must be in the appropriate mode to allow proper operation. The Transmit mode is theolder Stealth Sweep, whereas the new Transmit (SDA Compatible) mode is for the faster sweep refreshwith digital and scrambled carriers present. SDA Compatible mode is the only mode compatible withDSAM-6000 field meters. If DSAM-6000 is to be used on existing networks that already have SDAproducts, both in the headend and in the field, all equipment must be upgraded to SDA Compatiblecapability. The wrong mode selection will create erroneous readings.
Forward Telemetry Frequency must be in a vacant spectrum and at least 500 kHz from any othercarrier. It must also be within the bandwidth of the downstream spectrum. This is an FSK carrier andapproximately 500 kHz wide. The factory default is 51 MHz on the SDA-5500 transmitter, 52 MHz onthe receiver, and 53 MHz on the PathTrak HSM (a common JDSU element also typically located withthe SDA sweep gear).
Note: If diplex filters in the actives have a sharp roll-off, it is advisable to move the telemetry to a frequencythat is more reliable. The location and level of the telemetry may cause its second harmonic to interfere withexisting channels if not optimally adjusted.
Forward Telemetry Level determines the level of the telemetry signal. This should be set 10 dB belowthe video reference level. The telemetry level is adjustable from 20 to 50 dBmV in 2 dB increments. Themax is 50 dBmV; h