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It's probably an ionosonde — sending out HF radio signals not to communicate but to measure the reflections and thereby determine the current characteristics of the ionosphere. The signal is probably not actually a series of brief transmissions, but a continuous chirp transmission with continuously increasing frequency. Two reasons: As far as I know, this ...


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Often, the source of bands of noise in an SDR spectrum is locally generated RFI or EMI. During a neighborhood power outage, one might notice a large number of these bands disappear. Sharper bands in the waterfall can sometimes be mitigated by reducing or choking EMI sources in your "shack". Other possible sources for these bands can be ripple in passband ...


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