RE: LF: USB Sound Card?

[<hvanesce@comcast.net>]

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

From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Gary - G4WGT
Sent: Friday, August 15, 2014 3:25 PM
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: USB Sound Card?

 

Hi Warren,

Yes, I had an internal (on main board) & used it for a while for my grabber when 73kHz was first allocated to USA.
It was good to about 94kHz.

The SB0490 I suggested is only 96kHz :-((

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

.

On 15/08/2014 20:09, Warren Ziegler wrote:

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 <wd2xgj@gmail.com> 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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