Gary,

I use a number of expensive and inexpensive external (USB) audio interfaces, and I like them all (good sensitivity, good dynamic range); but I experience the following limitations:

A)

I have not been able to persuade Windows and/or Speclab to process 24 bits (I have been successful in applying 24-bit settings in Windows>ControlPanel>Sound  and Speclab, but have not acquired valid data after doing so; and accordingly have always used 16-bit settings with 24-bit external audio interfaces, even though I need at least 24 bits for dynamic range considering VLF and LF environmental noise in some of my locations)

B)

Similarly to the above, I have been able to set up Windows and Speclab for 192kHz sample rates, but have not been able to view past 48kHz without aliasing (and accordingly I settle for 96kHz settings and interfaces in most cases)

C)

All of my external audio interfaces have steep low-pass filters at or near 22kHz pole frequency, so SNR is compromised for signals at 20kHz and above. I’ve disassembled some of these interfaces in attempts to modify the low-pass filter cutoff frequencies, but without a schematic could not be certain regarding changes.

Have you seen any of the above issues with internal or external audio interfaces that you have used?

73,  Jim AA5BW

73, de Gary - G4WGT

MF-LF-VLF Grabber : http://myweb.tiscali.co.uk/wgtaylor/grabber2.html

Web : http://myweb.tiscali.co.uk/wgtaylor/index.html

.

I guess I should have been more specific .

What I am seeking is are some sound cards more stable with respect to sampling rate and calibration? Also, any advantage to 24bit A/D  for LF data modes?

 I wonder if anyone has tried 192kHz sample rate for direct reception of 73kHz?

 

73 & Tnx Warren

 

 

 

On Fri, Aug 15, 2014 at 2:27 PM, Warren Ziegler <[email protected]> wrote:

I just acquired a Windows Vista tower computer - the price was right it was free!

Seems that there is a problem with the internal sound card, but everything else checks out FB.

I plan on using it with WSPR and other digital modes, am thinking of an external USB sound card - will any old sound card do ? Or do I need one with a calibrated sampling rate? I suspect that I will need something really good for Spectrum Laboratory if I want to sample at microHertz rates.

 

73 & Tnx Warren K2ORS

 

 

 

 

--
73 Warren K2ORS
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