DK1NY's frequency finder - for general frequencies as well
my antenna for UHF-Satcom :
As we all
know, a lot of science fiction involves space travel. We
sometimes tend to forget that real life space travel already takes
place, albeit on a somewhat limited scale.
This week end I did a
little listening to spacecrafts on the radio. You may not believe it,
but space communications is not as difficult as many people would think.
I
was finding out when the ISS came over the horizon here and started
listening to a relay station for ham (amateur) radio situated on the
ISS. If there is not any spacewalks going on, the relay station is
active listening on the 435MHz (uplink) band (70cm) and transmitting on
the 145MHz (downlink) band (2m).
The downlink on 145.800MHz was
clearly audible with a scanner radio and a simple whip antenna, as soon
as I went out on the balcony of my apartment. On average the period
with audible signals is 10 minutes per pass, shorter when the pass is
near the horizon and longer when the station comes over my head.
Many
years ago I sometimes set my receiver to 143.625MHz in order to listen
for the MIR space station (yes - the Russian one), and have heard that
one talking to the Earth station.
On some occasions it is
possible to have a contact with one of the astronauts on the ISS, if
they have the free time and interest. Almost all the astronauts have
the license to transmit from up there.
In fact, the radio hams
have several satellite relays orbiting the Earth, giving them the
opportunity to try out space communications. Most of those are in a low
Earth orbit, and therefore they are only useable for a short time. Some
have a very elongated orbit (not really any right now), giving the
opportunity for longer communication periods.
Most of us know
about TV and communications satellites in the geostationary orbit (the
satellite follows the Earth's rotation and seems to be stationary over
a certain point on the Earth). The dream of some radio hams is getting
their satellite out there, giving 24/7 communications.
Just a
dream ... but maybe not any longer. There seems to be negociations
going on between the AMSAT (Amateur Satellite) organisation and
Inmarsat, about getting a lift with one of their satellites, and even
sharing the power from the solar panels. We never know if this will
come true, but I sure hope so.
Do not forget that the Space
Station is a rather big satellite and is very easy to see when above
the horizon. So - even if you cannot receive it on the radio you can go
outside and observe a *real life* manned spacecraft. if you want to
know when it can be observed at your place , go to Heavens Above
and find out. it is a good idea to register, so you can have your
location recognised when you log on.
When STS122
had just been launched, I went out to see if I could
spot it and the ISS. The ISS arrived right on time and was *very*
bright and easy to see (I missed the Shuttle, though). I had also
brought my scanner radio receiver with me, and just before the ISS went
into the Earth's shadow , I heard a carrier wave for a few seconds ,
followed by [chorosho] (Russian for "good") and a few more words in
Russian, since they were communicating with a ground station in Russia.
In
the first few orbits after launch of the space shuttle(s) and the last
few orbits before the re-entry (landing) the shuttle uses the frequency
259.700 MHz (AM) for clear voice communications.
A few weeks
later, when the STS-123 was launched, I joined a group listening for
the Shuttle "Endeavour". but since the high power (10 Watts)
transmitter of the spacecraft was out, they were only transmitting with
the low power (0.25 watts) transmitter. with my simple antenna and a
long cable in to the receiver the signal was lost here, but a few other
people around in Europe did hear them.
Since then I have had a preamplifier mounted at the antenna , so the
loss in the cable has been compensated.
In
the last few orbits before re-entry I listened for Endavour again - and
even with their low power transmitter it was audible here. Signals were
weak and noisy, but a few sentences were clearly heard here. Next time
I will have to do some recordings.