I've asked this question on several forums, and there seems to be no
concise answer.  My computer has the integrated "on board" sound, which
I have used successfully to decode digital modes of most types.  Now
that I am about to upgrade to General (or higher) license, and will be
able to transmit as well as receive, I want to upgrade the sound card
also.  I just ordered a "refurbished" Creative external MP3+ from
Creative, @$14.99.  This unit should give me better S/N ratio of around
100Db, and since it is external, hum pickup from the other computer
internal workings should be reduced or eliminated..  As to how it works
with the various digital modes, time will tell.  I'll post my results
with this when it is received and tried out.  Meanwhile, if anyone has
any other sound card expertise or good/bad reports on certain models,
please do share with the group.

Tnx es 73 de KCØPTO
Les
--- In [email protected], "Peter G. Viscarola" <[EMAIL PROTECTED]>
wrote:

> On the topic of sound cards for digital modes in general:
>
> While using a sound card with a wide frequency response, and using
high
> sampling rates, might intuitively appear to be a good idea, I'd
suggest
> this is not likely to be the case.
>
> Given that we tend to use the sound card to monitor a radio passband
> that's not (likely to be) more than 5KHz wide, sampling much above the
> Nyquist frequency for 5K (10K samples/second) seems
counter-productive.
>
> It seems to me that the key criteria for choosing a sound card for
> digital use would be:
>
> - Flat frequency response from (some low frequency such as) 100HZ to
> 5KHZ
> - Dynamic range in the area of 100db (and hence, a very low noise
floor)
>
> Additionally, it seems like it would probably be a good idea if the
> sound card had filtering to remove frequencies below 100Hz and above
> 5KHz.
>
> Thoughts?  What am I missing in this logic?
>
> de Peter K1PGV
>

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