Looking for NBFM receiver chip

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n1ist
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Looking for NBFM receiver chip

Post by n1ist » Fri Sep 28, 2018 6:06 am

I am looking for an NBFM receiver chip to be able to receive from a vhf wireless microphone (around 200 MHz). In the past, I would have gone with the old Motorola or National parts (like the MC3362, as used in many scanners) but they seem to have all vanished. I have checked SiLabs, but they only have wideband (broadcast) FM chips other than their weather radio, which only has two fixed frequencies. So what's available these days? I see the venerable SA604 still exists... I need low latency so that probably would rule out low-end SDR stuff.

Thanks.
/mike

jordanmills
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Joined: Mon Nov 12, 2018 12:15 pm

Re: Looking for NBFM receiver chip

Post by jordanmills » Mon Nov 12, 2018 12:56 pm

I've been looking into the same thing. Almost everything is discontinued and unavailable. The TH71221 seemed to fit the bill, barely. Except it's EOL so Mouser and Digikey are going to be limited to the last couple hundred they have on hand. The datasheet does not have too much clear information on how to use it for analog FM, but there's a separate application cookbook that has example circuits for using the demodulator output to get FM audio (6.7) and using a varactor to modulate the external crystal to match an FM audio signal (4.2).

https://www.melexis.com/en/documents/do ... x-cookbook

https://www.melexis.com/-/media/files/d ... elexis.pdf

I'm not sure what I'd use if that weren't available. But I think I'm going to give this one a shot.

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