Thread: Demodulator
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Old June 29th 07, 07:17 PM posted to rec.radio.amateur.homebrew
Joerg Joerg is offline
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First recorded activity by RadioBanter: Nov 2006
Posts: 58
Default Demodulator

Tim Wescott wrote:

Jimmie D wrote:

Revamping an old homebrew SW receiver I built about 30 years ago. Is
there an IC that will serve as an AM SSB FM detector. The existing
AM/SSB detector is on a board the size of a playing card.

You could probably twist some of the FM/IF detectors into doing that.
Many of them have RSSI outputs that go as the log of the signal
strength, I've seen literature that suggests you can block the DC from
that and feed an exponential stage to get AM detection with built-in
AGC. For SSB, if you switched out the quadrature filter for FM
detection and injected a BFO into the appropriate pin you could get SSB.

But if you're playing around with a board the size of a playing card,
why not build three optimized detectors, or get ambitious and slap down
a DSP with appropriate ADC and DAC resources?


But be careful with a DSP in a receiver. They require a clock and
generate all kinds of RF noises. Might have to be in a can.

Of course, a DSP can do all sorts of other stuff like DRM. Although I
doubt DRM will ever make it into the market.

--
Regards, Joerg

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