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Old 16-04-2019, 01:16   #70
tpreitzel
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A continuation of post #69 to illustrate the magnitude of processing required to produce adequate analog audio on shortwave:

https://ibb.co/yNj0LRH

This screenshot is busy and requires some explanation. First, a SOAPY RTL-SDR driver was used instead of a SOAPY RSP-1A driver since I was using an RTL-SDR V3 SDR on the Q-channel, i.e. no upconverter. The audio was managed by PulseAudio's Loopback device and routed to the I/Q Neg Split channel on DReaM's input. DReaM's output was via the FFT of the multi-band equalizer, qpaeq, on PulseAudio's default output device.

The reception and sound quality are quite good considering the use of a $20 dongle and 30' of wire antenna (MMDs-31). All of the rest of the processing was handled via software. Granted, the listener to these larger SW stations shouldn't NEED to equalize their unbalanced broadcasts on limited bandwidths as it's the transmitting station's responsibility. Furthermore, some limitations of analog just can't be overcome without digital.

Last edited by tpreitzel : 17-04-2019 at 00:14.
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