major earth station equipment - itso.int · 6/10/5244 - 3 antenna a satellite earth station antenna...
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6/10/5244 - 2
Major Earth Station Equipment
ANTENNA – Types – Parameters
Uplink – Modulation – Up-converters – Transmitters – Inter Facilities Link
RF Downlink – LNA / LNB – Down-converters – Demodulation – Inter Facilities Link
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Antenna
A satellite earth station antenna – An effective interface between the uplink equipment and free space – Must be directional to beam an RF signal to the satellite – Requires a clear line of sight between the antenna and the satellite
HPA
Antenna
Free space
HPA
Free space
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ANTENNA
ANTENNA PARAMETERS: GAIN
G (dBi) = 20.4 + 20 Log f + 20 Log D + 10 Log h
f = frequency in GHz D = diameter in meters h = antenna efficiency in decimal format
What should be the gain of a 9.3 m C-band antenna at 6.4GHz that is
62% efficiency ?
G = 20.4 + 20 Log 6.4 + 20 log 9.3 + 10 Log 0.62 G = 20.4 + 20 ( .806179) + 20 ( .968482) + 10 ( -0.2076) G = 20.4 + 16.12 + 19.37 - 2.08 G = 53.81 dBi
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ANTENNA
BEAMWIDTH:
For a given antenna, the higher the frequency the narrower the 3dB beamwidth. Therefore the receive band will be broader than the transmit.
For a given frequency band the larger the antenna aperture the smaller or narrower the beamwidth.
θ (deg.) = 21 f D
f = frequency in GHz D = diameter in meters
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Antenna
– Manual movement – Provides coverage of the entire satellite arc – Peaked on satellite with no further adjustments
– Motorized – Azimuth ± 180o from antenna center line (CL) – 5 - 90o – Tracking satellites in transfer orbit
– Typically Motorized – Azimuth ± 60o from center line (CL) – 5 – 90o Elevation – Full time service – Occasional use on multiple satellites
Full Motion
Limited Motion
Fixed
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Antenna
– Computer Track • Predict data from computer controls antenna movement
– Installed at base of the antenna (“Jog Controller”) – Toggle switches for AZ (CW/CCW), EL (UP/Down) and Polarizer – Serial data link for remote control with a computer – Transducers provide AZ & EL and Polarizer angle readouts
Antenna Position Controllers (APC)
Antenna Control Unit (ACU) – Manually position and polarize the antenna – Preset satellite locations stored in memory – Step Track
• Requires a suitable receiver to provide signal level to the ACU • Back and forth movement in AZ and EL to ensure peak signal level
– Memory Track • Creates a model of satellite motion for a twenty-four hour period • Uses this model to track the satellite
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Antenna
– Mono-pulse • Relative signal phase and the sharp slope of a tracking null is
used to determine peak position • It is not necessary to step the antenna to determine
satellite target orientation relative to the antenna’s RF axis • Utilizes an electrical means (phase comparison) rather than a
mechanical means (antenna stepping) to determine satellite orientation
• Responds more accurately and faster to satellite dynamics • Primary use is for tracking transfer orbits
Antenna Control Unit (ACU)
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Antenna Efficiency
Efficiency can never be 100%
Well-designed antennas have efficiency ratings of 50 - 70% – 60 – 65 % typical
Efficiency is affected by: – Spar and feedhorn blockage – Subreflector alignment and placement – Subreflector surface tolerance and design – Main reflector surface tolerance or deviation – Feed horn loss – On axis alignment – Polarization purity
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Antenna Types
Prime Focus parabolic reflector – Center Feed – Feed & strut blockage can be large – High feed line loss – Both TX and RX – Poor G/T performance
OMT
Feed
SPAR
RF
RF
MAIN REFLECTOR
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Antenna Types
Parabolic reflector Cassegrain – Typical use 5m or larger – Parabolic main reflector – Hyperboloidal subreflector – Subreflector and strut blockage small – Small feed line loss – Good G/T
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Antenna Types
Parabolic reflector Gregorian – Typical use 5m and larger – Parabolic main reflector – Ellipse subreflector – Subreflector and strut blockage small – Small feed line loss – Good G/T
RF
SUBREFLECTOREllipseOMT
MAIN REFLECTOR
RF
SPAR
Feed
SPAR
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Antenna Types
Parabolic reflector offset feed – Typical 3.7m and smaller – No feed blockage – Small feed line loss – VSAT applications
R F
R F
MAIN REFLECTOR
OMTSPAR
Feed
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Antenna Types
Simulsat – Receive Only – Captures signals across a 70° view arc – Up 35 satellites are received with uniform performance – Each satellite illuminates a specific area – Signals reflect to their corresponding C or Ku-Band feed – Feeds are adjusted, no antenna movement
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Antenna Types
– The system noise temperature is also reduced because the receiver looks at the cold sky instead of the warm earth
In a direct feed reflector, the feed horn is located at the focus or may be offset to one side of the focus
Large earth station antennas have a subreflector at the focus – The subreflector permits the antenna optics to be
located near the base of the antenna – Reduces losses because the length of the waveguide
between the transmitter or receiver and the antenna feed is reduced
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Antenna Subreflector
Gregorian – The subreflector is concave with an ellipsoidal surface – Ellipsoidal? A geometric surface or a solid figure shaped
like an oval. Any section through an ellipsoid is either an ellipse or a circle.
Cassegrain – The subreflector is convex with an hyperboloidal surface – Hyperboloidal? A mathematical surface whose sections
parallel to one coordinate plane form ellipses and those parallel to the other two coordinate planes form hyperbolas
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Antenna Focal Distance (f/d)
Focal Distance (f/d) – To calculate: f/d = D2/16d
• D = Antenna Diameter • d = Depth of Parabola
d = 0.6m
D = 3.8m
f/d
D = 3.8m
d = 0.8m
f/d
f/d = D2/16d D = 3.8 m D = 149.6 in
d = 0.6 m d = 23.63 in
f/d = 1.504 m f/d = 59.23 in
f/d = D2/16d D = 3.8 m D = 149.6 in
d = 0.8 m d = 31.5 in
f/d = 1.128 m f/d = 44.42 in
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Antenna
Deep dish antenna – Short focal length decreases the feedhorn’s ability to illuminate the
entire reflector area providing less gain – Can provide advantages
• Low elevation angles • Terrestrial interference
– Better antenna noise temperature
Shallow dish antenna – Long focal length increases the feedhorn’s ability to illuminate the
entire reflector area providing good gain – More susceptible to:
• Earth noise at low elevation angles • Terrestrial interference
– Affects antenna noise temperature
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Antenna De-Ice
Fabric Cover – Prevent snow/ice accumulation in the dish
Freezing perception will impact antenna performance – Snow or ice on the reflector surface
• Attenuates the signal • De-focus the antenna
Area’s with freezing perception require antenna de-icing Electric
– Blankets glued to the back of the reflector – Forced hot air with the back structure enclosed
Natural gas – Forced hot air with the back structure enclosed
Rain Blower – Blows air across feed input to prevent water buildup
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Antenna Feed System
Rain Blower – Blows air across feed input to prevent water buildup
1 Port – Receive Only
2 Port – Two Receive – One Transmit and One Receive
3 Port – One Transmit and Two Receive
4 Port – Two Transmit and Two Receive
Polarization adjustment – Single plane, transmit and receive are fixed and both rotate – Dual plane, transmit and receive rotate separately
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Ortho Mode Transducer (OMT) – Changes feeds circular W/G to two rectangular W/G’s – Separates and directs signals of two different polarities – Determines isolation for Circular Polarization
OMT and TRF
Transmit
TRF
Feed
LNA
Receive
H V
4 port feed will have an OMT and TRF for each polarity
Transmit Reject Filter (TRF) – Blocks transmit power from the Low Noise Amplifier
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FCC / ITU requirements for transmit patterns – 29-25log θ from 1 to 7o
– 8 dBi from 7 to 9.2o
– 32-25log θ > 9.2o
Antenna Pattern
Deg 29-25 log θ from peak
1 29.0 15.2 2 21.5 22.7 3 17.1 27.1 4 13.9 30.3 5 11.5 32.7 6 9.5 34.7 7 7.9 36.3 8 8.0 36.2 9 8.0 36.2 10 7.0 37.2 11 6.0 38.2
How are the curves applied?
– Calculations are subtracted from antenna gain
– i.e. antenna gain = 44.2 dBi
– Higher gain antenna will provide more discrimination
– i.e. 50 dBi – 29 = 21 dB
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Antenna Pattern
Deg from peak
1 15.2 2 22.7 3 27.1 4 30.3 5 32.7 6 34.7 7 36.3 8 36.2 9 36.2 10 37.2 11 38.2
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Uplink Components
Uplink Block Diagram – Modulator / Modem – Up-Converter – Power Amplifier – Antenna – Inter Facility Link (IFL)
• Fiber Optics • Co-axial cable • Patch Panels • Combiners / Splitters • Waveguide
Modem Up-Converter Transmitter FeedIFL IFL IFL
Antenna
Simplified Uplink Block Diagram
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Up-Converter (U/C)
The method used to achieve the conversion is heterodyning. That is the mixing of two different frequencies into a non-linear device ( mixer ) to produce two other frequencies equal to the sum or difference of the first two, while maintaining it’s characteristics
A device that converts an input signal known as the intermediate frequency (IF) to a desired higher frequency without disturbing the intelligence (modulation) on the incoming signal
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Up-Converter (U/C)
– 140 MHz to L-Band • 140 ±72 MHz input • 950 – 1450 MHz output • Non inverting • 72 MHz bandwidth
70 / 140 MHz IF to L-Band
– 70 MHz to L-Band • 70 ±18 MHz input • 950 – 1450 MHz output • Non inverting • 36 MHz bandwidth
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Up-Converter (U/C)
L-Band to C-Band – 950 - 1450 MHz input – 5.925 – 6.425 GHz output – Non inverting (4.900 GHz LO) – Inverting (7.375 GHz LO) – 500 MHz bandwidth
L-Band to Ku-Band – 950 - 1450 MHz input – 14.00 – 14.50 GHz output – Non inverting (LO = 13.050 GHz) – Inverting (LO = 15.450 GHz) – 500 MHz bandwidth
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U/C Frequency Calculations
– Modem IF Frequency = 74.5 MHz (6104.5 – 4900 -1200 + 70) – Uplink freq (-) BUC LO freq (-) U/C center freq (+) 70 MHz
Modem 70 Mhz to L-Band BUC74.5 MHz 1204.5 MHz HPA6104.5 MHz
Center Frequency1200 MHz LO = 4900 MHz
70 to L-Band to C-Band (Non Inverted) – Center Frequency of transponder (6100 MHz) – LO frequency of the BUC (4900 MHz) – Center frequency of Up-Converter = 1200 MHz (6100 – 4900)
• Bandwidth center freq (-) BUC LO freq – Carrier Uplink Frequency 6104.5 MHz
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Modem IF to L-Band BUC65.5 MHz 1270.5 MHz HPA6104.5 MHz
Center Frequency1275 MHz LO = 7375 MHz
U/C Frequency Calculations
– Modem IF Frequency = 65.5 MHz (7375 - 6104.5 - 1270 + 70) – BUC LO freq (-) Uplink freq (-) U/C center freq (+) 70 MHz
70 to L-Band to C-Band (Inverted) – Center Frequency of transponder (6100 MHz) – LO frequency of the BUC (7375 MHz) – Center frequency of Up-Converter = 1275 MHz (7375 – 6100)
• BUC LO freq (-) Bandwidth center freq – Carrier Uplink Frequency 6104.5 MHz
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Modem IF to L-Band BUC77.5 MHz 1157.5 MHz HPA14207.5 MHz
Center Frequency1150 MHz LO = 13050 MHz
U/C Frequency Calculations
– Modem IF Frequency = 77.5 MHz (14207.5 – 13050 -1150 + 70) – Uplink freq (-) BUC LO freq (-) U/C center freq (+) 70 MHz
70 to L-band to Ku-Band (Not inverted) – Center Frequency of transponder (14200 MHz) – LO frequency of the BUC (13050 MHz) – Center frequency of Up-Converter = 1150 MHz (14200 – 13050)
– Bandwidth center freq (-) BUC LO freq – Carrier Uplink Frequency 14207.5 MHz
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U/C Frequency Calculations
– Carrier Uplink Frequency 14207.5 MHz
Modem IF to L-Band BUC62.5 MHz 1332.5 MHz HPA14207.5 MHz
Center Frequency1340 MHz LO = 15540 MHz
70 to L-Band to Ku-Band (Inverted) – Center Frequency of transponder (14200 MHz) – LO frequency of the BUC (15540 MHz) – Center frequency of Up-Converter = 1340 MHz (15540 – 14200)
– BUC LO freq (-) Bandwidth center freq
– Modem IF Frequency = 62.5 MHz (15540 - 14207.5 - 1340 + 70) – BUC LO freq (-) Uplink freq (-) U/C center freq (+) 70 MHz
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Up-Converter (U/C)
70 MHz to C-Band – 70 ±18 MHz input – 5.850 – 6.425 GHz output – Non inverting – 36 MHz bandwidth
140 MHz to C-Band
– 140 ± 36 MHz input – 5.850 – 6.425 GHz output – Non inverting – 72 MHz bandwidth
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U/C Frequency Calculations
– Modem IF Frequency = 74.5 MHz (6104.5 – 6100 + 70) – Uplink freq (-) U/C center freq (+) 70 MHz
Modem Up-Converter74.5 MHz HPA6104.5 MHz
Center Frequency6100 MHz
70 MHz to C-Band – Center Frequency of transponder (6100 MHz) – Center frequency of Up-Converter = 6100 MHz – Carrier Uplink Frequency 6104.5 MHz
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U/C Frequency Calculations
Modem Up-Converter144.5 MHz HPA6104.5 MHz
Center Frequency6100 MHz
140 MHz to C-Band – Center Frequency of transponder (6100 MHz) – Center frequency of Up-Converter = 6100 MHz – Carrier Uplink Frequency 6104.5 MHz
– Modem IF Frequency = 144.5 MHz (6104.5 – 6100 + 140) – Uplink freq (-) U/C center freq (+) 140 MHz
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Up-Converter (U/C)
70 MHz to Ku-Band – 70 ±18 MHz input – 14.00 – 14.50 GHz output – Non inverting – 36 MHz bandwidth
140 MHz to Ku-Band – 140 ± 36 MHz input – 14.00 – 14.50 GHz output – Non inverting – 72 MHz bandwidth
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U/C Frequency Calculations
– Modem IF Frequency = 77.5 MHz (14207.5 – 14200 + 70) – Uplink freq (-) BUC LO freq (-) U/C center freq (+) 70 MHz
Modem Up-Converter77.5 MHz HPA14207.5 MHz
Center Frequency14200 MHz
70 MHz to Ku-Band – Center Frequency of transponder (14200 MHz) – Center frequency of Up-Converter = 14200 MHz – Carrier Uplink Frequency 14207.5 MHz
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U/C Frequency Calculations
– Modem IF Frequency = 147.5 MHz (14207.5 – 14200 + 140) – Uplink freq (-) BUC LO freq (-) U/C center freq (+) 140 MHz
Modem Up-Converter147.5 MHz HPA14207.5 MHz
Center Frequency14200 MHz
140 MHz to Ku-Band – Center Frequency of transponder (14200 MHz) – Center frequency of Up-Converter = 14200 MHz – Carrier Uplink Frequency 14207.5 MHz
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U/C Attributes Parameter Typical Value* Unit
Return Loss > 20 dB
Noise Figure < 15 dB
RF output
Return Loss > 20 dB
Spurious
Non-Carrier < -80 dBm
Carrier < -60 dBm
Third Order Intermodulation at 10 dB backoff from rated output power
< -40 dBc
Third Order Intercept > 23 dBm
IF/RF Performance (Transfer)
Gain Stability vs. Temperature at 0-50 Celsius Degree
< 1 dB
Gain Stability vs. Temperature 24 Hr. at constant drive and temp.
< 0.25 dB
Parameter Typical Value* Unit
AM/PM conversion at rated output power
< 0.1 degree/dB
Group Delay (per 40 MHz)
Linear < 0.05 ns/MHz
Parabolic < 0.01 ns/MHz2
Ripple < 1 ns P-P
Frequency Stability
Daily < 5 x 10-9
Yearly < 1 x 10-7
Over Operating Temperature < 1 x 10-8
Phase Noise (IESS 308/309 phase noise profile)
10 Hz < -30 dBc/Hz
100 Hz < -60 dBc/Hz
1 kHz < -70 dBc/Hz
10 kHz < -80 dBc/Hz
100 kHz < -90 dBc/Hz
1 MHz < -90 dBc/Hz
* For better performance, the selected value should be less or greater than as indicated
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Transceiver
Transceiver – Combination Power Supply, Up / down converter, HPA and LNA – Mounted on / at the antenna – 70 or 140 MHz IF input – C-Band output – Single or dual synthesized converters
• Uplink • Downlink
Power Supply
Up-Converter
Down-Converter
TXIF
RXIF
SSPA
LNA
Transceiver Block Diagram
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Transceiver Attributes Parameter Typical Value* Unit
IF Input VSWR < 1.5 : 1
RF Output VSWR < 1.5 : 1
Gain Flatness over any 40 MHz
< 1 dB
Gain Stability vs. Temperature (0-50 Celsius Degree)
< 1.5 dB
Spurious at rated output power
< -50 dBc
Harmonic Output at rated output power
< -50 dBc
Third Order Intermodulation at 3 dB backoff from rated output power
< -26 dBc
Receive Characteristics
RF Input VSWR < 1.5 : 1
IF Output VSWR < 1.5 : 1
Gain Flatness over any 40 MHz
< 1.5 dB
Parameter Typical Value* Unit
Gain Stability vs. Temperature (0-50 Celsius Degree)
< 1.5 dB
Noise Figure < 1 dB
Frequency Stability
Daily < 5 x 10-9
Yearly < 1 x 10-7
Over Operating Temperature < 1 x 10-8
Phase Noise (IESS 308/309 phase noise profile)
10 Hz < -30 dBc/Hz
100 Hz < -60 dBc/Hz
1 kHz < -70 dBc/Hz
10 kHz < -80 dBc/Hz
100 kHz < -90 dBc/Hz
1 MHz < -90 dBc/Hz
* For better performance, the selected value should be less or greater than as indicated
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Transmitters (HPA)
Block Up-Converter (BUC) – Non linear – Provides up conversion from L-band to C or Ku band – SSPA Provides amplification – Requires external 10 MHz reference – Typical output power 1 to 10 Watts – 500 MHz bandwidth – Typical application on remote VSAT with L-Band Modem – ≈ 3 dB OBO for multi carrier operation
L-Band U/C
Bandpass Filter
OUT
SSA SSPA
10 MHz
IN
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Transmitters (HPA)
Solid State Power Amplifier (SSPA) – Typical output power 5 to 200 Watts – 500 MHz bandwidth – Non Linear – L-Band Up-Converter optional
• Requires external 10 MHz reference • Requires Diplexer
– Typically ≈ 3 dB OBO for multi carrier operation
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SSPA Attributes Parameter Typical
Value* Unit
Input VSWR < 1.3 : 1
Output VSWR < 1.3 : 1
Gain Flatness over any 40 MHz
< 0.5 dB
Gain Stability vs. Temperature (0-50 Celsius Degree)
< 1 dB
Noise Figure < 10 dB
Spurious at rated output power
< -65 dBc
Harmonic Output at rated output power
< -60 dBc
Third Order Intermodulation at 3 dB backoff from rated output power
< -26 dBc
AM/PM conversion at rated output power
< 2 degree/dB
Parameter Typical Value*
Unit
Phase Noise (IESS 308/309 phase noise profile)
10 Hz < -30 dBc/Hz
100 Hz < -60 dBc/Hz
1 kHz < -70 dBc/Hz
10 kHz < -80 dBc/Hz
100 kHz < -90 dBc/Hz
1 MHz < -90 dBc/Hz
Group Delay (per 40 MHz)
Linear < 0.05 ns/MHz
Parabolic < 0.01 ns/MHz2
Ripple < 1 ns peak to peak
* For better performance, the selected value should be less or greater than as indicated
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Transmitters (HPA)
Traveling Wave Tube Amplifier (TWTA) – Typical output power 100 – 750 Watts – 500 MHz bandwidth – Non Linear – Built in BUC optional
• Requires 10 MHz external reference and Diplexer – ≈ 7 dB OBO for multi carrier operation
– ≈ 4 dB OBO with linearizer for multi carrier operation
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Transmitters (HPA)
HPA HIGH POWER AMPLIFIER • TRAVELING WAVE TUBE AMPLIFIER • WIDEBAND ( FULL SPECTRUM ) GREATER 500MHz • NON LINEAR
– SMALL SIGNAL SUPRESSION – AMPLITUDE TRANSFER CURVE
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Transmitters (HPA)
TRAVELING WAVE TUBE AMPLIFIER – SMALL SIGNAL SUPRESSION – AMPLITUDE TRANSFER CURVE – INTERMODULATION
f 1 - f 2 f 1 + f 2f1 f2
( f 1 - f 2 ) - f 1
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TWTA Attributes Parameter Typical
Value* Unit
Phase Noise (IESS 308/309 phase noise profile)
10 Hz < -30 dBc/Hz
100 Hz < -60 dBc/Hz
1 kHz < -70 dBc/Hz
10 kHz < -80 dBc/Hz
100 kHz < -90 dBc/Hz
1 MHz < -90 dBc/Hz
Group Delay (per 40 MHz for C-band / per 80 MHz for Ku-band)
Linear < 0.05 ns/MHz
Parabolic < 0.01 ns/MHz2
Ripple < 0.5 ns peak to peak
Parameter Typical Value*
Unit
Input VSWR < 1.3 : 1
Output VSWR < 1.3 : 1
Gain Flatness over any 40 MHz
< 1 dB
Gain Stability vs. Temperature (0-50 Celsius Degree)
< 0.25 dB
Noise Figure < 15 dB
Spurious at rated output power
< -65 dBc
Harmonic Output at rated output power
< -60 dBc
Third Order Intermodulation at 7 dB backoff from rated output power
< -24 dBc
AM/PM conversion at rated output power
< 6 degree/dB
* For better performance, the selected value should be less or greater than as indicated
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Transmitters (HPA)
Klystron Power Amplifier (KPA) – Typical output power 1000 to 3000 Watts – Non linear – 40 or 80 MHz bandwidth – OBO ≈ 2 dB for dual carrier operation
≈ 7 dB for multi carrier operation
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Transmitters
KLYSTRON POWER AMPLIFIER
NARROWBAND , TUNED CAVITY FREQUENCY RESPONSE GROUP DELAY
HIGH POWER NON-LINEAR
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KPA Attributes
Parameter Typical Value*
Unit
Input VSWR < 1.3 : 1
Output VSWR < 1.3 : 1
Gain Stability vs. Temperature (0-50 Celsius Degree)
< 0.25 dB
Spurious at rated output power
< -65 dBc
Harmonic Output at rated output power
< -60 dBc
Third Order Intermodulation at 7 dB backoff from rated output power
< -28 dBc
AM/PM conversion at rated output power
< 4 degree/dB
Parameter Typical Value*
Unit
Phase Noise (IESS 308/309 phase noise profile)
10 Hz < -30 dBc/Hz
100 Hz < -60 dBc/Hz
1 kHz < -70 dBc/Hz
10 kHz < -80 dBc/Hz
100 kHz < -90 dBc/Hz
1 MHz < -90 dBc/Hz
Group Delay (per 40 MHz for C-band / per 80 MHz for Ku-band)
Linear < 0.1 ns/MHz
Parabolic < 0.03 ns/MHz2
Ripple < 2 ns peak to peak
* For better performance, the selected value should be less or greater than as indicated
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Downlink Components
Downlink Block Diagram – Demodulator / Modem – Down-Converter – LNA – Antenna – Inter Facility Link (IFL)
• Fiber Optics • Co-axial cable • Patch Panels • Combiners / Splitters • Waveguide
Modem Down-Converter LNA FeedIFLIFL
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Low Noise Amplifier (LNA)
Lower the Noise Temperature, the better the performance
Low Noise Amplifier
DC Regulator
Input Output
Power
Input Waveguide – CPR-229 C-Band – WR-75 Ku-Band
Output Coaxial connector – N-Type (50 ohm) Standard C-Band – SMA (50 ohm) Standard Ku-Band
Typical 3 stage amplification (Designed to keep noise down) – No Frequency Conversion
“Noise Temperature” is the amount of noise added – Specified in degrees K for C-Band
• 20o – 40oK Typical – Specified as Noise Figure (NF) for Ku-Band
• 0.7 to 1.0 Typical (50o – 75oK)
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Low Noise Block Down-Converter (LNB)
Output Coaxial connector – N-Type (50 ohm) – F-Type (75 ohm)
Low Noise Amplifier
DC Regulator
Input Output
Power
LNA with a Block Down-Converter built in Provides Frequency Conversion
– DRO (Dielectric resonator Oscillator) • ± 150 kHz to ± 500 kHz C-Band • ± 150 kHz to ± 900 kHz Ku-Band
– PLL (Phase Locked Loop) • ± 5 kHz to ± 25 kHz C-Band • ± 5 kHz to ± 50 kHz Ku-Band
– External (10 MHz reference) Input Waveguide
– CPR-229 C-Band – WR-75 Ku-Band
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Low Noise Amplifier (LNA/LNB)
Frequency stability of LNB critical depending on type of service
Designed to provide the lowest noise contribution as possible – 20o – 40o K noise temperature typical for C-band – 70o – 90o K noise temperature typical for Ku-band – 50 to 60 dB Gain typical
Mounted as close as possible to the OMT waveguide ports
One of the most critical components of an antenna system – Major factor in determining the systems figure of merit (G/T)
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LNA / LNB Attributes LNA
Parameter Typical Value*
Unit
Input VSWR < 1.3 : 1
Noise Temperature for C-Band < 45 K
Noise Temperature for Ku-Band
< 100 K
Output
Output VSWR < 1.3 : 1
Gain Flatness over any 40 MHz < 0.2 dB
Gain Stability vs. Temperature at 0-50 Celsius Degree
< 2 dB
Third Order Intercept > 20 dBm
Group Delay (per 40 MHz)
Linear < 0.01 ns/MHz
Parabolic < 0.01 ns/MHz2
Ripple < 1 ns P-P
LNB
Parameter Typical Value* Unit
Input VSWR < 2.5 : 1
Noise Temperature for C-Band < 45 K
Noise Temperature for Ku-Band
< 100 K
Output
Output VSWR < 2.5 : 1
Gain Flatness over any 40 MHz < 1 dB
Frequency Stability over Temperature
< 50 kHz
Phase Noise (IESS 308/309 phase noise profile)
10 Hz < -30 dBc/Hz
100 Hz < -60 dBc/Hz
1 kHz < -70 dBc/Hz
10 kHz < -80 dBc/Hz
100 kHz < -90 dBc/Hz
1 MHz < -90 dBc/Hz
* For better performance, the selected value should be less or greater than as indicated
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Down-Converter (D/C)
A device that converts an RF input signal to a desired lower frequency known as the intermediate frequency (IF) without disturbing the intelligence (modulation) on the incoming signal
The method used to achieve the conversion is
heterodyning. That is the mixing of two different frequencies into a non-linear device ( mixer ) to produce two other frequencies equal to the sum or difference of the first two, while maintaining it’s characteristics
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Down-Converter (D/C)
Ku-Band to L-Band (LNB) – 11.70 – 12.20 GHz input – 950 - 1450 MHz output – Non inverted (10.75 GHz) – 500 MHz bandwidth
C-Band to L-Band (LNB) – 3.70 to 4.2 GHz input – 950 - 1450 MHz output – Inverted (5150 MHz LO) – 500 MHz bandwidth
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D/C Frequency Calculations
– Modem IF Frequency = 1270.5 MHz (5150 – 3879.5) – LNB LO freq (-) Downlink freq
Modem LNB1270.5 MHz 3879.5 MHz
LO = 5150 MHz
C-band to L-Band – Inverted C-Band (LNB) – LO frequency of the LNB (5150 MHz) – Carrier Downlink Frequency 3879.5 MHz
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– Carrier Downlink Frequency 11907.5 MHz
D/C Frequency Calculations
Modem LNB1157.5 MHz 11907.5 MHz
LO = 10750 MHz
Ku-Band to L-Band – Non Inverted Ku-Band (LNB) – LO frequency of the LNB (10750 MHz)
– Modem IF Frequency = 1157.5 MHz (11907.5 – 10750) – Downlink freq (-) LNB LO freq
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Down-Converter (D/C)
L-Band to 70 / 140 MHz IF
– L-Band to 140 MHz • 950 – 1450 MHz input • 140 ± 36 MHz output • Non inverting • 72 MHz bandwidth
– L-Band to 70 MHz • 950 – 1450 MHz input • 70 ±18 MHz output • Non inverting • 36 MHz bandwidth
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D/C Frequency Calculations
– Modem IF Frequency = 65.5 MHz (5150 – 3879.5 -1275 +70) – LNB LO freq (-) Downlink freq (-) D/C center freq (+) 70 MHz
Modem Down-Converter65.5 MHz LNB1270.5 MHz
Center Frequency1275 MHz
3879.5 MHz
LO = 5150 MHz
Inverted C-Band (LNB) – Center Frequency of transponder (3875 MHz) – LO frequency of the LNB (5150 MHz) – Center frequency of Down-Converter = 1275 MHz (5150 – 3875)
– LNB LO freq (-) Bandwidth center freq – Carrier Downlink Frequency 3879.5 MHz
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D/C Frequency Calculations
– Modem IF Frequency = 65.5 MHz (11907.5 – 10750 - 1150 +70) – Downlink freq (-) LNB LO freq (-) D/C center freq (+) 70 MHz
Modem Down-Converter77.5 MHz LNB1157.5 MHz
Center Frequency1150 MHz
11907.5 MHz
LO = 10750 MHz
Non Inverted Ku-Band (LNB) – Center Frequency of transponder (11900 MHz) – LO frequency of the LNB (10750 MHz) – Center frequency of Down-Converter = 1150 MHz (11900 – 10750)
– Bandwidth center freq (-) LNB LO freq – Carrier Downlink Frequency 11907.5 MHz
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Down-Converter (D/C)
C-Band to 70 MHz – 3.700 – 4.200 GHz input – 70 ±18 MHz output – Non inverting – 36 MHz bandwidth
C-Band to 140 MHz – 3.700 – 4.200 GHz input – 140 ± 36 MHz output – Non inverting – 72 MHz bandwidth
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D/C Frequency Calculations
– Modem IF Frequency = 74.5 MHz (3879.5 – 3875 + 70) – Downlink freq (-) U/C center freq (+) 70 MHz
Modem Down-Converter74.5 MHz LNA3879.5 MHz
Center Frequency3875 MHz
3879.5 MHz
C-Band (70 MHz) – Center Frequency of transponder (3875 MHz) – Center frequency of Down-Converter = 3875 MHz – Carrier Downlink Frequency 3879.5 MHz
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D/C Frequency Calculations
– Modem IF Frequency = 144.5 MHz (3879.5 – 3875 + 140) – Downlink freq (-) U/C center freq (+) 140 MHz
Modem Down-Converter144.5 MHz LNA3879.5 MHz
Center Frequency3875 MHz
3879.5 MHz
C-Band (140 MHz) – Center Frequency of transponder (3875 MHz) – Center frequency of Down-Converter = 3875 MHz – Carrier Downlink Frequency 3879.5 MHz
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Down-Converter (D/C
Ku-Band to 140 MHz – 11.70 – 12.20 GHz input – 140 ± 36 MHz output – Non inverting – Inverting – 72 MHz bandwidth
Ku-Band to 70 MHz – 11.70 to 12.20 GHz input – 70 ±18 MHz output – Non inverting – Inverting – 36 MHz bandwidth
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D/C Frequency Calculations
Ku-Band (70 MHz)
Modem Down-Converter77.5 MHz LNA11907.5 MHz
Center Frequency11900 MHz
11907.5 MHz
– Modem IF Frequency = 77.5 MHz (11907.5 – 11900 + 70) – Downlink freq (-) U/C center freq (+) 70 MHz
– Center Frequency of transponder (11900 MHz) – Center frequency of Down-Converter 11900 MHz – Carrier Downlink Frequency 11907.5 MHz
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D/C Frequency Calculations
Ku-Band (140 MHz)
Modem Down-Converter147.5 MHz LNA11907.5 MHz
Center Frequency11900 MHz
11907.5 MHz
– Modem IF Frequency = 147.5 MHz (11907.5 – 11900 + 140) – Downlink freq (-) U/C center freq (+) 140 MHz
– Center Frequency of transponder (11900 MHz) – Center frequency of Down-Converter 11900 MHz – Carrier Downlink Frequency 11907.5 MHz
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D/C Attributes Parameter Typical Value* Unit
AM/PM conversion at rated output power
< 0.1 degree/dB
Group Delay (per 40 MHz)
Linear < 0.05 ns/MHz
Parabolic < 0.01 ns/MHz2
Ripple < 1 ns P-P
Frequency Stability
Daily < 5 x 10-9
Yearly < 1 x 10-7
Over Operating Temperature < 2 x 10-8
Phase Noise (IESS 308/309 phase noise profile)
10 Hz < -30 dBc/Hz
100 Hz < -60 dBc/Hz
1 kHz < -70 dBc/Hz
10 kHz < -80 dBc/Hz
100 kHz < -90 dBc/Hz
1 MHz < -90 dBc/Hz
Parameter Typical Value* Unit
RF Input
Return Loss > 20 dB
Noise Figure < 15 dB
IF output
Return Loss > 20 dB
Spurious
Non-Carrier < -80 dBm
Carrier < -60 dBm
Third Order Intermodulation at 10 dB backoff from rated output power
< -50 dBc
Third Order Intercept > 25 dBm
RF/IF Performance (Transfer)
Gain Stability vs. Temperature at 0-50 Celsius Degree
< 1 dB
Gain Stability vs. Temperature 24 Hr. at constant drive and temp.
< 0.25 dB
* For better performance, the selected value should be less or greater than as indicated
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Patch Panels
8:1
IF Patch Panel
Modem
Modem
Modem
Modem
DATAPatch Panel
1:8
Up-Converter
Down-Converter
1:2HPA
1:2 LNA
10 dB Coupler
40 dB Coupler
50 dB Inject
Coupler
IF Patch Panel
TP-1 TP-2
TP-3TP-4
Uplink & Downlink Patch Panel and RF monitor block diagram
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Patch Panels
– Connection between the downlink splitter and modem receive • Monitor output of Down-Converter
Patch Panel’s provide a convenient place to interconnect equipment within the uplink and downlink chains
• Test equipment can be patched in to test either direction (satellite or terrestrial)
Data Patch Panel – Connection between the DTE and Modem
• Ease of testing without having to get into equipment rack to disconnect data cables
IF Patch Panels – Connection between the modem transmit and uplink combiner
• Cross patch modems – Connection between Combiner and Up-Converter
• Monitor output of combiner (All modem transmit carriers)
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Patch Panels
– Splitter at Down-Converter input (TP-4) • Monitor full 500 MHz downlink spectrum
RF Monitor Points
– 10 dB coupler on Up-Converter output (TP-1) • Monitor Up-converter output
– 40 dB coupler at feed input (TP-2) • Monitor aggregate transmit carriers and power
– Receive inject coupler (TP-3) • Capability to inject carrier prior to LNA
– Ability to calibrate downlink chain