OLSG Report_Final_06_05_12 - Interagency Operations Advisory ...
OLSG Report_Final_06_05_12 - Interagency Operations Advisory ...
OLSG Report_Final_06_05_12 - Interagency Operations Advisory ...
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Optical Link Study Group (<strong>OLSG</strong>) <strong>Final</strong> <strong>Report</strong><br />
IOAG.T.<strong>OLSG</strong>.20<strong>12</strong>.V1<br />
RELAY FEEDER LINK DOW NLINK BUDGET<br />
INPUT PARAM ETERS<br />
LINK BUDGET<br />
Range 39.77E+03 km Tx Ave Power 26.99 dBm<br />
Elevation 20 deg Tx Photons / Pulse 3.90E+08<br />
TRANSMITTER<br />
Tx Antenna Gain<br />
1<strong>06</strong>.27 dBi<br />
Modulation Type DPSK Tx Transmission Loss -4.81 dB<br />
Tx Pointing Loss<br />
-0.27 dB<br />
Tx Wavelength 1.55 µm<br />
Tx Ave Power 0.5 W Isotropic Space Loss -290.17 dB<br />
Tx Data Rate 10.0E+09 Hz Atmospheric Loss -1.65 dB<br />
Tx Aperture Diam 0.1016 m Rx Antenna Gain <strong>12</strong>6.14 dBi<br />
Tx Angular Diam 4.01 arcsec Array Gain 0.00 dB<br />
Tx Footprint Diam 7.73E+02 m Rx Transmission Loss -5.80 dB<br />
Tx Optical Transmission 33.0 % Rx Pointing Loss 0.00 dB<br />
Tx Depointing 0.50 arcsec Rx Fiber Coupling Loss -4.00 dB<br />
Total Optical Path Loss<br />
-74.29 dB<br />
Uncoded Slot Rate 20.0E+09 s -1<br />
Uncoded Bits Per Word 0.50 Ave Power at Rx Detector -47.31 dBm<br />
Photons / Pulse at Rx Detector 14.51<br />
ATMOSPHERIC LOSSES<br />
Atm Zenith Transmittance 95.0 % Required Photons / Pulse 7.00<br />
Relative Airmass 2.90 Link M argin 3.17 dB<br />
Atm Transmission Along LOS 86.2 %<br />
Scintillation Loss -1.0 dB<br />
RECEIVER<br />
Rx Aperture Diam 1.00 m<br />
Rx FOV 5.00 arcsec<br />
Rx Depointing 0.00 arcsec<br />
Rx Optical Transmission 26.3 %<br />
Rx Array Size 1 apertures<br />
Fiber Coupling Loss -4.00 dB<br />
Required Photons / Pulse 7.00<br />
Code Rate 0.50<br />
Figure 80: Example downlink budget for an optical feeder link in an Earth<br />
relay scenario<br />
4.1.5.2.2.2 Uplink<br />
A sample uplink beacon budget for the GEO relay scenario is shown in Figure 81. The<br />
transmitter, with the configuration of Ground Station 2, consists of four 15 cm apertures.<br />
The average power per aperture is 2.5 W, for a total transmitted power of 10 W. The<br />
irradiance required at the receiver aperture is based on the acquisition procedure of LLCD.<br />
The link closes with a good margin of more than 21 dB; therefore, an average power of<br />
about 40 mW per aperture could be sufficient on the ground.<br />
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