Re: Approach to demodulating AM-signals?

Mr M wrote:
Hello



I need to sample and demodulate an AM-signal that is between 30 kHz to 100
kHz. The signal has a bandwidth of about 10 kHz.



What approach should I use?



I’m thinking of using a 16 bit ADC with a maximum sampling frequency of 500
ksps. Maybe using an FPGA to control the ADC. The FPGA can also be used to
do the signal processing.



How high sampling frequency should I use?


High enough so that your reception works.

Nyquist in this case is 220kHz. You need to juggle the sophistication of your anti-aliasing filters vs. the speed requirements of your algorithm. All I can say for sure is that the smallest realistic sampling rate is around 300kHz.

I would also be concerned about that 10kHz signal riding on a 30kHz carrier -- you're going to have some aliasing there, too, that will make a simple envelope detector output look pretty crude and rude.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Posting from Google? See http://cfaj.freeshell.org/google/
.

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