9 February 2015

hopping sounder (10Khz bw, 10 sps)

observed on 19845 Khz (cf), hopping its working frequency.

I used first the oscilloscope to get a measure of the distances between two consecutive sweeps:

The sounder is 100 msec delay between the sweeps, so (1000 msec/100 msec) = 10 sweeps per second (or 10 sps). The sweeps can also be observed, and measured, in the frequency domain: as expected, the sweep rate is 10 sps (100 ms distance between two sweeps). Modulation is FMOP.

This signal hops frequencies in a specific manner. It starts moving up the band in various intervals then it goes back and starts again, overlapping Amateur and broadcast shortwave bands.

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