[amsat-bb] SpaceX Dragon C2+ and the ISS CUCU Communications Orbit 29 @ 3:23 AM EST over Chelmsford, MA

Bryce Salmi bts2637 at rit.edu
Thu May 24 10:54:22 PDT 2012


     So my dad and brother and I all decided to get up and catch the pass
over Chelmsford, MA at 3:23AM this morning of the ISS and Dragon. We were
pleasantly suprised due to the pre-dawn light when we saw a bright ISS and
not too far behind it a trailing dimmer Dragon C2+ flying overhead! We used
our normal amateur satellite setup with an Arrow handheld antenna and a
Yaesu VX-8R. At 10 seconds into the audio you hear us change the mode of
the radio to AM.

We know from the FCC papers I linked to in the sound file description that
400.5 MHz was the only SpaceX UHF licensed frequency and it was well known
that the CUCU is a UHF radio. Being 153.6 Kbps it's likely a form of spread
spectrum or similar so we only expected to hear a small portion of the
transmissions. I suggest reading the soundcloud description to get a full
sense of where to listen in the audio but there are clear data bursts in
there. CUCU and the ISS only need to transmit to each other so unlike most
amateur satellites that are designed to be heard from the ground... we're
picking up what's left of the 1.5W as it leaks past the spacecraft to the
ground. The signals are weak but enjoy!



Bryce Salmi

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