The USAF SGLS (Space-Ground Link System)


From a satellite communications course that I went to and from a IEEE publication on Shuttle communications we know that the present-day SGLS uses S-band for up- and down-links, but that the uplink band is different from that of NASA and all other Western space agencies.




Frequencies, FreqUp 1763.721-1839.795 MHz, 20 channels 4004 kHz spacing
Function 1 PRN ranging
Function 2 Voice 30 kHz
Function 3 Command FSK/AM 95,76, 65 kHz tones at 1 or 2 kbps
Function 4 Analog 1.25 MHz subcarrier



FreqDown = FreqUp * 256/205(1+2V/C) = 2202.50-2297.500 MHz, 20 channels, 5000 kHz spacing
Carrier 1 PRN ranging, 1.024 MHz (PSK, PI/2), 1.2500 MHz voice, 1.700(PSK, FM/FM) PCM/PM. PAM/FM or FM/FM
Carrier 2 High bit-rate PCM, 5 MHz below carrier 1
Carrier 3 FM modulated data, 35 MHz maximum bandwidth

Carrier 3 is very interesting. The wideband FM signal seems to be an image link of some sort.

Specifically for the Shuttle the frequency bands have been divided as follows:


Uplink Low band 1763-1804 MHz
  High band 1803-1840 MHz
Downlink Low receive 2200-2253 MHz
  High receive 2251-2301 MHz


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