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Well I guess I've never run into this because I've only played with AFSK. After some more experimenting, I can say: Input impedance of whatever you're interfacing to makes a big difference. 20 Hz through .01uF shows some attenuation even into 1M-ohms, and it bombs out at 600-ohms. With...

Your typical AFSK modulated carrier at 300 bps or 1200 bps uses a 1200 Hz mark and a 2200 Hz space (or a variation in that general area). It's not unusual to see such stuff interfaced to microphone inputs and speaker outputs, neither of which can really be expected to pass audio below 300 Hz...

How low? I just observed a sine wave put through a .01uF ceramic cap from 100 Hz to 5 kHz. No distortion. No attenuation. I even dropped it down to 100mV for some extra noise. Looks the same coming out as it does going in.

What is?

So it looks like this thread is a little old, but I just tore into a BC350C and wanted to share a couple things not mentioned previously: There are a couple things about pin 9 of that 3361 chip that may be a problem depending on what you're interfacing to. 1) There's just as much 455 kHz IF...

A good point, Mike. I occasionally get to maintain big $$$ recording systems in a public safety environment so I definitely understand the importance of recalling a specific block of recordings based on a date/time. But I also think this is less important to the hobbyists here on RR...

I can't seem to find a thread on this subject, but I suspect it's been discussed before. A lot of audio archives for those not-so-busy feeds are mostly full of recorded silence. I doubt this has a huge impact on the size of the compressed audio files on the server, but it sure makes trying to...