Signal spectrum of Sweden's Odin satellite

Sven Grahn

It may be instructive to compare observed spectra of satellite signals with the known characteristics of a satellite transmitter. The Swedish Odin satellite provides a good example. It transmits about 750 kbit/sec PCM with phase modulation with index 1.86 radians. The first example of signals observed is the "waterfall" below which is 50 kHz wide around the carrier frequency at 2208.135 MHz.

The graph above from ground tests of Odin only show
the signal peaks associated with the main bit rate.

The picture on the left shows a more detailed
spectrum that agrees rather well with the observed
in-orbit spectrum above

The 15 small peaks between those spaced about 750
kHz apart can be seen in the spectrum at the top of
the page which covers a narrower frequency range.

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