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[aprssig] APRS propagation monitor

Stephen H. Smith wa8lmf2 at aol.com
Wed Jun 6 20:49:44 UTC 2012


On 6/6/2012 4:41 PM, Patrick Wood wrote:
> But therein lies the flaw in your test.  When you use good hardware,
> then it is unlikely to be a problem.  When you use the junk soundcard
> chips on most motherboards you will likely get a totally different
> result.
>
> p
>
> On Wed, Jun 6, 2012 at 4:30 PM, Stephen H. Smith<wa8lmf2 at aol.com>  wrote:
>> By the way, the sound system used for these tests was a Griffin Electronics
>> "iMic" external USB-connected sound system that is far superior to the junk
>> noisy motherboard-based sound systems in most PCs.    Details on the iMic
>> here on my website:
>>
>> .<http://wa8lmf.net/ham/imic.htm>
>>
>


The iMic is a reasonably-priced gadget (about $25-$30).  The motherboard-based 
sound systems on most cheap PCs are so awful, I wouldn't consider using them in 
any case where a reasonable alternative exists.

Junk sound systems are an epidemic problem especially on SSTV where clueless 
newbies simply WON'T CALIBRATE apps like mmSSTV to compensate for the sometimes 
100s of parts-per-million sampling error rates.   (Sampling errors result is 
severely-slanted SSTV pics at the other end.)    mmSSTV provides a very easy 
cal routine that involves listening to WWV's ticks while displaying them on a 
special display screen, but at least 90% of mmSSTV users never bother to use it.

The iMic's sample rate calibration out-of-the-box is virtually perfect - no 
calibration drill needed.







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