[amsat-bb] Re: Video of indoor, ultra-cheap cubesat operations

Bruce Robertson ve9qrp at gmail.com
Tue Jan 29 18:07:35 PST 2008

Continuing this series of observations, using very simple antennas
indoors with my FT-817:

I worked on a eastward 5 deg. max elevation pass of XI-V, or CO-58,
this evening. This cubesat has a nominal output of 80mW. Its periodic
transmission makes it less ideal than CO-55 for this sort of
experimentation, but the break between transmissions is not as long as
LO-19's: in my experience with this low pass it never doppler-shifted
out of the 500 Hz filter while silent. I had to have only the exterior
wall between me and the bird for it to be reliably heard.

If I've done the math right, this is a free-space path loss of about
153 dB on a, roughly, +20 dBm signal, meaning that the receiver can
hear down to at least -133 dBm at 500 Hz bandwidth (since we haven't
factored in the losses due to the indoor reception).

A dipole mounted directly on a BNC copied VO-52's 2m downlink quite
well for a couple of minutes, both from the second storey of our home
and from the first. By the time I found my video camera, there was
apparently no activity. Possibly the dipole's pattern got in the way
of reception.

I would be very interested to hear if anyone else has had success with
similar minimal equipment. I hope to take this setup to a more urban
environment and see if it will still work, say, outdoors.

73, Bruce

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