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From: karn@faline.bellcore.com (Phil R. Karn)
Newsgroups: sci.space.shuttle,rec.ham-radio
Subject: Re: Space Shuttle Communications
Message-ID: <1389@faline.bellcore.com>
Date: Tue, 15-Sep-87 12:31:02 EDT
Article-I.D.: faline.1389
Posted: Tue Sep 15 12:31:02 1987
Date-Received: Thu, 17-Sep-87 05:34:18 EDT
References: <1008@scicom.alphacdc.com> <2646@ames.arpa> <136@splut.UUCP>
Distribution: na
Organization: Bell Communications Research, Inc
Lines: 50
Summary: shuttle frequencies are public
Xref: mnetor sci.space.shuttle:315 rec.ham-radio:2546

> I am reluctant to give the frequencies of the other two UHF channels,
> because I don't know how many squirrels read this group.  I trust 95%
> of you, but one bad apple could screw up a major national asset.  Sigh.
> "Paranoia strikes deep" -- Buffalo Springfield.

The shuttle comm frequencies are public information. From my Rockwell
STS-1 press kit, the three UHF AM frequencies are: 296.8 (primary),
259.7 (secondary), and 243.0 Mhz (emergency).

The S-band frequencies are:

2287.5 Mhz (PM downlink - primary)
2217.5 Mhz (PM downlink - secondary)
2250.0 Mhz (FM downlink - primary)
2205.0 Mhz (FM downlink - development flight instrumentation)
2106.4 Mhz (PM uplink - primary)
2041.9 Mhz (PM uplink - secondary)
1831.8 Mhz (PM uplink - DoD primary)
1775.7 Mhz (PM uplink - DoD secondary)

The links operate in either a high speed or low speed mode:
 
Uplink 
                High speed      Low speed 
voice           2 @ 32 kb       1 @ 24kb 
command         1 @ 8 kb        1 @ 8 kb 
total           72 kb           32 kb 
 
Downlink 
 
voice           2 @ 32 kb       1 @ 32 kb 
telemetry       1 @ 128 kb      1 @ 64 kb
total           192 kb          96 kb

As Ron said earlier, the data stream is multiplexed stuff with digital
voice and telemetry. However, all of the data formats are also public
information. I have a NTIS report on the performance of the
communications system during the STS-2 ascent, and in an appendix are
complete details on everything you need - frame sync vectors, channel
assignments, etc. In addition to the digital data, the PM downlinks
repeat a 1.7 Mhz ranging tone. For the non-DoD uplinks, the carrier
frequency of the downlink transmitter is phase locked to 240/221 times
the uplink frequency, also for tracking.  While certainly challenging, this
is not outside of the capabilities of a dedicated amateur.

The FM downlinks can carry a variety of stuff, e.g., television [probably
analog], 128 kb/s real-time engine data or 192 kb/s playbacks of
recorded data.

Phil