Thursday, January 21, 2016

Speech processor

A speech processor would help to cut through the QRM. So I build one.
It is a complex unit. It contains a small 12 MHz ssb transmitter and receiver for 12 MHz.
The signal out of this small SSB transceiver is limited by two diodes connected anti parallel.
Then the signal is filtered by a xtal filter that contains a single xtal. This filtered signal is detected by the SSB receiver. This results in compressed audio.

Clipping could be done on the audio signal but then only a little clipping can be done. The audio sounds distorted when more clipping is done. When clipping the SSB signal much more clipping can be done with good signal quality.

I took some ideas form the dsb clipper designed by PA0FRI. My processor makes real SSB instead. It also has a second xtal filter.

The compressed signal sounds good.

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