Signals from the Briz-M stage that launched SES 4, 14 February 2012

Sven Grahn


The Proton launch vehicle was launched from Baikonur at 1936 UT on 14 February 2012 carrying the SES 4 satellite.

On the first pass orbit after launch, at 2105 UT, very strong signals were picked up in Stockholm, Sweden on 1018.5 MHz. The waterfall spectrum is hsown below. Strong spectral components were seen at 16 kHz, 32 kHz. Discrete spectral lines can also be seen at 3.2 kHz intervals. Interestingly, both the main carrier and the 32 kHz spectral lines were modulated with slow frequency-shift keying. One can also see a "spectral fog" across the signal spectrum.  The gray area near the main carrier indicates the bandwidth of a CW demodulator that was applied in the software-defined receiver.

During the following night signals on 1018.5 MHz returned on several occassions (see below). The last signals on 1018.5 MHz were seen at about 0650 UT on 15 February.


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