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*Subject*: RE: [amsat-bb] DSP Possibilities ?*From*: "Howie DeFelice" <hdefelice@xxxxxxxxxxxxxx>*Date*: Thu, 21 Sep 2000 16:20:22 -0400

I think your bits/hz calculations are with FEC. Uncoded QPSK would produce 2 bits/Hz, 8PSK without coding is 3 bits/Hz and 16QAM is 4 bits/Hz. This would reduce the transmitted symbol rate to the data rate divided by the number of bits/Hz. Of course, I can't imagine using these schemes on amateur satellites (or any other satellites for that fact) without some FEC. I could be wrong, but I don't think changing the modulation effects the sample rate for the modulator, but it does increase the work load from a number crunching view. On the other hand, the demodulator's sampling rate should be lower due to the decreased symbol rate. I would imagine that the number crunching inside the demod would also increase. The net sum result is that if you take some of the burden off the sample rate, you use up the processing power somewhere else, and it's most likely NOT a linear tradeoff... Howie AB2S ---- Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA. To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org

**Follow-Ups**:**Re: DSP Possibilities ?***From:*John Stephensen, KD6OZH

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