<html><body><div style="color:#000; background-color:#fff; font-family:arial, helvetica, sans-serif;font-size:12pt"><div style="RIGHT: auto"><SPAN style="RIGHT: auto">Hi Ron,</SPAN></div>
<div style="RIGHT: auto"><SPAN style="RIGHT: auto"></SPAN> </div>
<div style="BACKGROUND-COLOR: transparent; FONT-STYLE: normal; FONT-FAMILY: arial, helvetica, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 16px; RIGHT: auto"><SPAN style="RIGHT: auto">I have one PC that does this. A quick<VAR id=yui-ie-cursor></VAR> and easy check is to turn off VAC (Virtual</SPAN></div>
<div style="BACKGROUND-COLOR: transparent; FONT-STYLE: normal; FONT-FAMILY: arial, helvetica, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 16px; RIGHT: auto"><SPAN style="RIGHT: auto">Audio Cable) function - a checkbox on the PSDR screen. Then hookup your computer</SPAN></div>
<div style="BACKGROUND-COLOR: transparent; FONT-STYLE: normal; FONT-FAMILY: arial, helvetica, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 16px; RIGHT: auto"><SPAN style="RIGHT: auto">speaker to the headphone jack on Hermes instead of your computer. When I did this,</SPAN></div>
<div style="BACKGROUND-COLOR: transparent; FONT-STYLE: normal; FONT-FAMILY: arial, helvetica, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 16px; RIGHT: auto"><SPAN style="RIGHT: auto">the audio went from scratchy to clean. Running the DPC checks as suggested did not</SPAN></div>
<div style="BACKGROUND-COLOR: transparent; FONT-STYLE: normal; FONT-FAMILY: arial, helvetica, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 16px; RIGHT: auto"><SPAN style="RIGHT: auto">indicate any issue with the problem computer.</SPAN></div>
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<div style="BACKGROUND-COLOR: transparent; FONT-STYLE: normal; FONT-FAMILY: arial, helvetica, sans-serif; COLOR: rgb(0,0,0); FONT-SIZE: 16px; RIGHT: auto"><SPAN style="RIGHT: auto">-- Tom, N5EG</SPAN></div>
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<DIV style="BORDER-BOTTOM: #ccc 1px solid; BORDER-LEFT: #ccc 1px solid; PADDING-BOTTOM: 0px; LINE-HEIGHT: 0; MARGIN: 5px 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; HEIGHT: 0px; FONT-SIZE: 0px; BORDER-TOP: #ccc 1px solid; BORDER-RIGHT: #ccc 1px solid; PADDING-TOP: 0px" class=hr contentEditable=false readonly="true"></DIV><B><SPAN style="FONT-WEIGHT: bold">From:</SPAN></B> Ron Nelson <ronelson99@gmail.com><BR><B><SPAN style="FONT-WEIGHT: bold">To:</SPAN></B> hpsdr@lists.openhpsdr.org <BR><B><SPAN style="FONT-WEIGHT: bold">Sent:</SPAN></B> Thursday, November 22, 2012 11:37 PM<BR><B><SPAN style="FONT-WEIGHT: bold">Subject:</SPAN></B> Re: [hpsdr] TAPR Hermes - Noise on Audio Out<BR></FONT></DIV><BR>***** High Performance Software Defined Radio Discussion List *****<BR><BR>Thanks to all for comments and suggestions.<BR><BR>On a different desktop computer, Hermes works fine with no extraneous audio noise. I tried with both PowerSDR 2.2.3 (10/27/12) and
cuSDR. Works great!<BR><BR>On my "problem" desktop PC the audio output noise continues to be completely reproducible. More tests:<BR><BR>I updated from PowerSDR 2.2.3 (10/07/12) to (10/27/12) - made no difference in the noise. So I am using the latest software now.<BR><BR>The noise is completely independent of the audio settings, volume, sample rate, sample size, etc. It is on both the headphone and speaker outputs. Everything points to oscillation of the audio output stage. The ADC and FPGA are working fine - the RF spectrum and signals are as expected. I can receive stations, but it is very annoying to listen with the constant loud noise, and forget about listening to weak stations.<BR><BR>With PowerSDR in the "Off" state there is no audio output, as expected. With the ethernet cable disconnected the audio output also turns off, as expected.<BR><BR>The noise is there whether I use headphones or speakers.<BR><BR>I tried different ethernet cables
(direct to PC) with no change.<BR><BR>Because I have such a good testbed for tracking down the problem ;->, I am willing to try some mods. Adding capacitance to the audio outputs or power for the D-A converter has been suggested. I may try this after a good nights sleep. Or I may try adding a different ethernet port to the PC to see if that makes a difference.<BR><BR>73<BR>Ron<BR>NR5ON<BR>_______________________________________________<BR>HPSDR Discussion List<BR>To post msg: <A href="mailto:hpsdr@openhpsdr.org" ymailto="mailto:hpsdr@openhpsdr.org">hpsdr@openhpsdr.org</A><BR>Subscription help: http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org<BR>HPSDR web page: http://openhpsdr.org<BR>Archives: http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/<BR><BR><BR></DIV></DIV></BLOCKQUOTE></div></div></body></html>