[Linrad] Re: RX overrun error

[Leif Asbrink <sm5bsz.com; leif@xxxxxxxxxxxxxxxx>]

Hello Jan,

> What RX overrun error 0 means? I am getting this error almost immediately
> when I hit D to proceed SSB. I tried different configuration, but I get it
> even with all default parameters. 
Overrun errors is when Linrad does not fetch data from the soundcard in
time. Some data is then lost. There is a counter associated with overrun
errors and if you do not see the number increase it happened just once and
that would not affect performance although it is a problem that should be
reported on this list. Thank you:-)

> I also have one more error - RX A/D speed error. 
That is most probably a serious error. 

> Both errors appear regardless sampling speed. I am using Lenovo W500
> notebook, with Windows Vista, Core 2 Duo T9400 @xxxx GHz, 4 GB RAM, internal
> sound cards Conexant  High Definition SmartAudio 221.
There are many soundcards - and many of them do not have correct drivers
for Vista. I have recently assembled a computer with two quad core Xeon
processors and I find that nearly nothing works properly under Vista, 
and Windows 7. Not even the 64 bit XP is ok. The problems may be related
to the PCI bus and the chip-set. I have not investigated it in depth yet,
but it seems that the same soundcard and drive routine works ok on a 
single-core machine.

> I had Windows XP on the notebook, but it behaves the very same? I also tried
> use external FireWire sound card Presonus FireBox and Virtual Audio Cable
> sound devices, same results.
RX A/D speed errors are reported when the input speed is wrong. Typically
far too low. In case you do not see overrun errors with an increasing number
the problem is that the soundcard is not serviced because the CPU(s) are busy.

> When I tried these sound devices with WSJT, sampling correction factors were
> very close to 1 (1.0001, 1.0002).
> 
> Any recommendation/advise welcome.
Try Linrad in newcomer mode. That is without second fft and generally less
demanding for the computer. You might try higher priority for Linrad
and a lower value for "Max DMA rate"

Linrad-03.06 and earlier are very sensitive to actions causing other programs
to signal redraw events to Linrad. It is normal to see overrun errors as 
well as speed errors if one moves around the windows of other programs over
the screen. Linrad-03.07 will ignore such redraw events and just update
the screen a couple of times per second when a burst of redraw events is
received (they may arrive at a rate of 1000 per second.)

Maybe someonme else can give you ideas about what is going wrong. Maybe
visual effects are enabled and implemented in software. If they use
hardware accelerators in the videocard they might be harmless, but
if they switch off interrupts for too long, the soundcard would loose
data. Linrad-03.07 might be less sensitive to visual effects. I will
upload it in the near future.

   73

  Leif / SM5BSZ

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