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 />
M ARS (FAR RANGE) DOW NLINK BUDGET<br />
INPUT PARAM ETERS<br />
LINK BUDGET<br />
Slant Range 4.00E+08 km Tx Ave Power 36.02 dBm<br />
Elevation 30 deg Tx Photons / Pulse 1.09E+13<br />
TRANSMITTER<br />
Tx Antenna Gain<br />
1<strong>12</strong>.98 dBi<br />
Modulation Type <strong>12</strong>8-PPM Tx Transmission Loss -5.19 dB<br />
Tx Pointing Loss<br />
-0.<strong>05</strong> dB<br />
Tx Wavelength 1.55 µm<br />
Tx Ave Power 4.0 W Isotropic Space Loss -370.22 dB<br />
Tx Data Rate 10.0E+<strong>06</strong> Hz Atmospheric Loss -0.64 dB<br />
Tx Aperture Diam 0.22 m Rx Antenna Gain 147.72 dBi<br />
Tx Angular Diam 1.85 arcsec Array Gain 0.00 dB<br />
Tx Footprint Diam 3.59E+<strong>06</strong> m Rx Transmission Loss -4.89 dB<br />
Tx Optical Transmission 30.3 % Rx Pointing Loss 0.00 dB<br />
Tx Depointing 0.10 arcsec Total Optical Path Loss -<strong>12</strong>0.29 dB<br />
Uncoded Slot Rate 365.7E+<strong>06</strong> s -1 Ave Power at Rx Detector -84.27 dBm<br />
Uncoded Bits Per Word 3.50 Photons / Pulse at Rx Detector 10.22<br />
ATMOSPHERIC LOSSES<br />
Required Photons / Pulse 1.87<br />
Atm Zenith Transmittance 95.0 % Link M argin 7.38 dB<br />
Relative Airmass 1.99<br />
Atm Transmission Along LOS 90.3 %<br />
Scintillation Loss -0.2 dB<br />
RECEIVER<br />
Rx Aperture Diam <strong>12</strong>.00 m<br />
Rx FOV 5.00 arcsec<br />
Rx Depointing 0.00 arcsec<br />
Rx Optical Transmission 32.4 %<br />
Rx Array Size 1 apertures<br />
Required Photons / Pulse 1.87<br />
Code Rate 0.50<br />
Figure 60: Example downlink budget for a Mars (far-range) Deep Space<br />
scenario.<br />
3.7.5.2 Uplink Budget<br />
Sample uplink beacon budgets for near-range and far-range Mars scenarios are reported in<br />
Figure 61 and Figure 62, respectively. The transmitter consists of nine 7 cm apertures, which<br />
provide a beam divergence of about 30 μrad (5.82 arcsec). The average power per aperture<br />
is 555.6 W, for a total transmitted power of 5 kW. In the calculation, the scintillation loss (or<br />
turbulence loss) is computed as Strehl ratio 2 and accounts for spread loss and beam<br />
wandering, under the assumptions of a seeing of 2 arcsec (Fried parameter r 0 of 5 cm, at<br />
zenith, at a wavelength of 500 nm). The considered receiver implements a photon-counter<br />
array.<br />
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