Linux-Hams archive - August 1999: Re: soundmodem on SBPro

Re: soundmodem on SBPro

Cathryn Mataga (fnzcjr.bpaqacfntq@pmc.edu)
Tue, 03 Aug 1999 17:03:44 -0700

As it just so happens, I have the hardware manual for Sound Blasters,
up to and including SB16. Hmm, there are some interesting
switches here. There are 2 bits of mic volume at bits d1 and d2 of
mixer register 0xa. At 0xc. there's 2 bits for input source at d1 and
d2. WHere 0,2 = mic, 1=cd input, and 3 = line in. This is probably
the problem. I'll bet mixer register 0xc defaults to 0. Also, there
a bit for low pass filter at 0xc in bit d3, which should be set to 1 for
off.

At 0xe, it d5 set to 1 for output low pass filter OFF, and bit d1
is 0 for MONO out.

Hamish Moffatt wrote:
>
> On Tue, Aug 03, 1999 at 12:57:16PM +0000, Gerd wrote:
> > [setting input gain level using smmixer]
> > >
> > > I've got the problem sorted out now -- nothing that couldn't be fixed
> > > with a good text editor and a C compiler! I'm not sure why smmixer
> > > won't let you set the input gain, but my copy does now. I have packet working
> > > on the sbpro now.
> >
> > So how about making a diff and submit it to the public (eg. into this
> > list) ? :)
>
> Tom told me that he does not think the mixer should affect the input
> gain for recording, only for playback (passthrough). This did not seem
> to be my experience but he is more knowledgable than I on this topic.
>
> > A problem with your squelch and how it is interacting with the rest
> > of the audio part of your receiver. Here you'll have to look for a
> > possible modification, or build your own squelch circuit.
>
> Do you think it is a problem to operate with the squelch open always?
> The soundmodem seems to do a pretty good carrier detect anyway.
>
> I bought an ICOM IC-02A HT yesterday for packet so perhaps that will
> behave a bit better. I like the way ICOM and Yaesu are using the same
> interface for PTT on their HTs; I plugged this ICOM straight into my
> TNC and it worked fine.
>
> Hamish
> --
> Hamish Moffatt Mobile: +61 412 011 176 dwzqt@fdn.com
> Rising Software Australia Pty. Ltd. http://www.risingsoftware.com/
> Phone: +61 3 9894 4788 Fax: +61 3 9894 3362 USA: 1 888 667 7839

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