jrm@sage0.gsfc.nasa.gov (John Mattox) (11/16/90)
Ron Parise asked me to post this in response to the request of
cole@SAMSON.phys.virginia.edu under Subject: Re: Atlantis and the DoD:
Hi Folks!
This is in response to the question about shuttle frequencies. The space
shuttle transmits on three frequency bands, UHF, S-Band, and Ku-Band.
The UHF frequencies are simple AM voice and very easy to copy. These
frequencies are used for launch and landing operations, EVA comunications,
(i.e. from the spacesuits back and forth to the shuttle), and occasionally
as an additional voice downlink if a ground station is being used. With
nearly global TDRS coverage, however, ground stations are seldom used.
The frequncies in use are:
296.8 MHz - air to ground, or orbiter to suit
259.7 MHz - air to ground, or suit to orbiter
279.0 MHz - suit to orbiter or suit to suit
243.0 MHz - standard Mil aircraft emergency freq.
The S-Band system is one of the primary orbiter downlink bands. The voice
channels are digital slope delta modulation and are mux'ed in with the
rest of the orbiter telemetry, very difficult to copy. Much of the
downlink TV is on S-Band also but it is analog wideband FM and should be
easily copyable. This is NOT usually NTSC video however! It is called Frame
Sequential Color (FSC) in which a black and white frame is taken first
through a green filter, then through a red filter then through a blue filter.
These frames are recombined on the ground to produce a color image. I'm not
sure what happens if you take the demodulated video and put it into an
NTSC monitor. You might actually get an acceptable B/W picture.
The frequencies are:
2287.5 MHz - primary digital downlink
2250.0 MHz - wideband FM with either main engine analog
telemetry during launch, or TV during orbit
operations.
The Ku-Band system is used in conjunction with the tracking and data
relay satellites and is used much more heavily in Spacelab flights than in
others. The data is *very* high rate digital (50 Mbits/sec range) and
therefore essentially impossible for you to demodulate and decommutate
in your basement. Nevertheless the shuttle transmits on 15.003GHz. You
should also note however that these transmissions are directed toward
the TDRS satellite with a high gain antenna and would therefore not be
copyable on the ground anyway.
The UHF frequencies are fun to listen to but are not heavily used
except during EVA's. You rarely hear anything on non-EVA flights
anymore. Although there is nothing like hearing a few words directly
from the shuttle, the best way to keep track of what is going on is
to listen to one of the shortwave frequencies used by the various NASA
radio clubs (especially the Goddard radio club WA3NAN) to retransmit
the Shuttle air to ground communications 24 hrs a day (or at least any
time the crew is awake).
Happy Listening!
Ron WA4SIR
STS-35 crew
--
+----------------------------------------------------------------------------+
| John Mattox |
| NASA/ Goddard Space Flight Center Internet: jrm@sage0.gsfc.nasa.gov |
| Code 662 DECnet: LHEAVX::MATTOX |jrm@sage0.gsfc.nasa.gov (John Mattox) (11/16/90)
Ron Parise asked me to post this in response to the request of
cole@SAMSON.phys.virginia.edu under Subject: Re: Atlantis and the DoD.
Hi Folks!
This is in response to the question about shuttle frequencies. The space
shuttle transmits on three frequency bands, UHF, S-Band, and Ku-Band.
The UHF frequencies are simple AM voice and very easy to copy. These
frequencies are used for launch and landing operations, EVA comunications,
(i.e. from the spacesuits back and forth to the shuttle), and occasionally
as an additional voice downlink if a ground station is being used. With
nearly global TDRS coverage, however, ground stations are seldom used.
The frequncies in use are:
296.8 MHz - air to ground, or orbiter to suit
259.7 MHz - air to ground, or suit to orbiter
279.0 MHz - suit to orbiter or suit to suit
243.0 MHz - standard Mil aircraft emergency freq.
The S-Band system is one of the primary orbiter downlink bands. The voice
channels are digital slope delta modulation and are mux'ed in with the
rest of the orbiter telemetry, very difficult to copy. Much of the
downlink TV is on S-Band also but it is analog wideband FM and should be
easily copyable. This is NOT usually NTSC video however! It is called Frame
Sequential Color (FSC) in which a black and white frame is taken first
through a green filter, then through a red filter then through a blue filter.
These frames are recombined on the ground to produce a color image. I'm not
sure what happens if you take the demodulated video and put it into an
NTSC monitor. You might actually get an acceptable B/W picture.
The frequencies are:
2287.5 MHz - primary digital downlink
2250.0 MHz - wideband FM with either main engine analog
telemetry during launch, or TV during orbit
operations.
The Ku-Band system is used in conjunction with the tracking and data
relay satellites and is used much more heavily in Spacelab flights than in
others. The data is *very* high rate digital (50 Mbits/sec range) and
therefore essentially impossible for you to demodulate and decommutate
in your basement. Nevertheless the shuttle transmits on 15.003GHz. You
should also note however that these transmissions are directed toward
the TDRS satellite with a high gain antenna and would therefore not be
copyable on the ground anyway.
The UHF frequencies are fun to listen to but are not heavily used
except during EVA's. You rarely hear anything on non-EVA flights
anymore. Although there is nothing like hearing a few words directly
from the shuttle, the best way to keep track of what is going on is
to listen to one of the shortwave frequencies used by the various NASA
radio clubs (especially the Goddard radio club WA3NAN) to retransmit
the Shuttle air to ground communications 24 hrs a day (or at least any
time the crew is awake).
Happy Listening!
Ron WA4SIR
STS-35 crew
--bh@eng.auburn.edu (Brian Hartsfield) (04/05/91)
Could somebody post or e-mail me a list of frequencies where the shuttle air-to-ground communications can be picked up? I am in Auburn, AL. Brian Hartsfield