[hpsdr] Mercury Audio Output Problem - Solutions

[Doug Bade]

Digging further I found that if I drop the buffer size to 512 on the 
192k sample rate I can get the audio to clean up.. With the buffer 
size at 512k it is pretty solid and clean. The CPU load is up 
substantially but it allows 192k setting to work. Clearly it is a 
buffer/sample rate / CPU USB issue...

Any thoughts on could it be the USB cable ?? I dug out a cable from 
one of my page scanners that has a ferrite in the cable on the pc 
end.. seems like it should be a good idea ????

Thanks for the input regarding VACS as that would seem to point to 
internal timing issues that seems consistent with what I see ..

Is any of the new code for the Mercury going to impact this analysis 
I am seeing ??? Or is this motherboard right on the edge of useable???

Doug
KD8B


At 09:42 PM 1/5/2009, Doug Bade wrote:
>***** High Performance Software Defined Radio Discussion List *****
>
>Hello Group;
>         At the suggestion of Duane I did in fact try 96k and 48k 
> and audio sounds great, well much better anyhow... apparently this 
> is maybe a USB issue as he suggested to me...
>
>This is a problem as this is my Atom 330 board.... Has anyone else 
>who owns this board seen this or is this some issue locally??? I am 
>still hearing a 60 hz hum on the audio but the audio is totally 
>intelligible now as long as I do nor use 192k.... I have lots of hum 
>potential sources so the hum may now be externally caused by me and 
>shielding... but clearly the 192k setting is nasty on my setup..
>
>This setup is Mercury only and Ozy... no Penny....
>
>Doug
>KD8B
>
>
>
>
>At 08:54 PM 1/5/2009, DUANE BAADE wrote:
>>Doug,
>>I had a similar problem, and it was quite interesting, and I am not 
>>sure what the real solution is. If I had the 192kHz sample rate 
>>selected, then the audio was really bad. If I selected 96kHz sample 
>>rate, then the audio was really nice. However, then there is 
>>problem with images. This was with the factory software loaded into 
>>the fpga. Last Friday nite on Team Speak, Phil Harmon said that my 
>>USB was probably not handeling things as it should. I moved to 
>>another computer that I had, and now it seems to work ok at the 
>>196kHz sample rate. I also had problems when Penny was also 
>>installed. I had to set both the 10MHz and 122.88MHz clocks to be 
>>comming from Penny or the trace was way up and lots of noise. On 
>>the second computer, it works better, but it still works best if I 
>>use Penny for both of the clock frequencies. I have not tried any 
>>of the new firmware yet, hopefully that will help too. Just my 
>>2cents worth, hope it helps.
>>
>>Duane Baade    W5PNM
>>
>>
>>
>>From: Doug Bade <kd8b at thebades.net>
>>To: hpsdr at lists.hpsdr.org
>>Sent: Monday, January 5, 2009 6:17:20 PM
>>Subject: [hpsdr] Mercury Audio Output Problem
>>
>>***** High Performance Software Defined Radio Discussion List *****
>>
>>     I am hoping someone has something to point me here as I am making no
>>headway... I am running Mercury and Ozy in Slot 6 and 2 respectively.
>>I am able to calibrate levels from a signal from my service monitor.
>>I am having terrible distorted and buzzing audio coming out the
>>bottom audio jack as well as the next one up. I have tried 2 separate
>>preamplified speaker sets... one my bose.... both sound fine on the
>>windows audio default jack.. but both sound terrible from Mercury..
>>
>>It is as if some 60hz like audio is massively being introduced into
>>the audio.. 50 % of content like level making even speech
>>unintelligible in am or fm modes and obscuring my 1khz tone from my
>>service monitor in each mode respectively...  I have tried moving
>>boards around on atlas.. I have only Mercury and Ozy installed. Clock
>>is off Mercury in both cases. all jumpers default... From the SDR
>>panadapter it looks relatively normal other than I see the noise
>>floor bouncing up and down a few db ever second or 2....
>>
>>The audio sounds heterodyne-ish.... as well as distorted buzzing....
>>
>>Any thoughts???? Anyone had this happen before??
>>
>>Doug
>>KD8B
>>
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