Re: [amsat-bb] 38.4kbps sound card DSP demodulator

[Luc Langehegermann <luc@xxxxxxxx>]

Hello Howard,

You need to pay close attention to these cards. Often the 192kHz are only for
the playback side, especially on consumer rated cards.

I own an M-Audio Audiophile card, that will do 96kHz full duplex (but only has
an audio bandwidth of 22kHz it seems) with btw should be enough for G3RUH 38k4.
I peeked a look in the source code for the soundmodem from Tom, HB9JNX, and
there the sample rate is set to only the bitrate, here the code extract:

        if (params[0]) {
                s->bps = strtoul(params[0], NULL, 0);
                if (s->bps < 4800)
                        s->bps = 4800;
                if (s->bps > 38400)
                        s->bps= 38400;
        } else
                s->bps = 9600;
        *samplerate = s->bps + s->bps / 2;

You also see here the upper limit is 38k4. Anyone already tried it?

73, Luc


Zitat von Howard Long <howard@howardlong.com>:

> 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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