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Re: 38.4kbps sound card DSP demodulator



9.6 kbps FSK modems that process the receiver disriminator output require a 6.25
kHz audio response so a 38.4 kbps modem will require a 25 kHz frequency
response. A 192ksps ADC will have usually have a 40-60 kHz frequency response
and the sampling rate is an integer multiple of 38,400 so it can be done. Just
make sure that the SoundBlaster doesn't have a 20 kHz LPF ahead of the ADC.

I think the main problem is finding a radio with a 64 kHz bandwidth filter ahead
of the disriminator. You loose 4-6 dB with the 160-250 kHz wide filters that are
normally available.

73,

John
KD6OZH

----- Original Message -----
From: "Howard Long" <howard@howardlong.com>
To: <amsat-bb@AMSAT.Org>
Sent: Wednesday, 06 October, 2004 11:24 UTC
Subject: [amsat-bb] 38.4kbps sound card DSP demodulator


> Is this possible?
>
> For example, I have a Soundblaster Audigy 2 apparently with the ability to
> resolve 192kHz stereo sound (and 96kHz in 6 channels).
>
> So DSP experts, can a 38.4kbps G3RUH demodulator be written with these
> higher sampling rate devices?
>
> 73 Howard G6LVB
> ----
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----
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