Larry, The compander in PowerSDR COMPRESSES signal peaks and EXPANDS signal minimums. The compander in PowerSDR is applied only to the transmit audio signal. It does not affect the receive signal. The compander in your MacIntosh amp is the same animal except that they provide separate control for the compression & expansion levels while PowerSDR has only one control which adjusts both.
The article you referenced is a little confusing. When it was talking about compressing audio before the A-D converter (transmit) and expanding it after the D-A converter (receive), it was referring to a specific application in the recording industry where you have a closed system. That is, you have control over both the recording (transmit) process and the playback (receive) process, such as in a digital audio recorder used in a sound recording studio. Using this technique, you can achieve a nearly distortion-free method of increasing the signal-to-noise ratio. Obviously, in radio communications, we only have control of one end of the process, either the transmit signal processing or the receive signal processing, but not both (unless you only work stations using Flex radios, too). By-the-way, I used to be the studio facilities engineering manager for RCA Records way back in the analog recording days. We had compressors back then, but expander circuits were a little more tricky. They relied on positive feedback & were prone to oscillation. What you can do with DSP these days is nothing short of amazing. 73, Ray, K9DUR http://k9dur.info _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/
