[Linrad] Re: Elderly computers.

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

Hi Corneliu,

> I encounter foll error message:
> 
> DA SYNC ERRORS 1

The input runs at some fixed speed that is controlled
by a crystal oscillator. Linrad knows the nominal
speed, but in real life there is always an error.

The loudspeaker output is usually controlled by another 
crystal and Linrad knows what the speed is supposed to be, 
but it is also has an error associated with it.

When you click on a signal to start producing output, Linrad
will produce output data at the nominal output rate by
use of a fractional re-sampler. (Assuming there are no 
frequency errors) Linrad monitors the total time delay
from input to output and tries to keep it constant. That is
done by small changes of the fractional resampling ratio.

The error: DA SYNC ERRORS NN (where NN is a number) tells
you that Linrad failed to make the time delay from input 
to output constant. In case NN is a small number, you may
ignore it (and the associated glitch in the output.) If
it happens regularly it will be a good idea to find out
what is causing this error. There may be more severe 
errors that are caused by the same underlying problem.

SYNC ERRORS can be caused by:

1) Badly selected parameters that make Linrad use 
   more memory than your OS allows. That means that
   data areas are swapped to the hard disk with
   unpredictable time delays occuring now and then.

2) The OS is running other applications that do not
   respect Linrads need for short latency times. You
   may ease Linrads need in this respect by setting 
   a lower limit to the maximum DMA rate.

3) You have selected parameters that causes Linrad
   to load your CPU too much. In case this is really the
   reason it means that you have detected a problem that
   could perhaps be cured. Linrad is multi-threaded and
   if one thread uses the CPU for a too long time without
   releasing it to see if some other thread needs it, all
   sorts of timing problems can occur.

4) You may have detected a bug of some kind that I am 
   not (yet) aware of.


By the way, I know you have a Perseus HF receiver. I am
not so sure you can use it under Windows 98 because it
can be difficult to get USB 2 under Win 98. Further, the
Perseus needs the DLL supplied by Nico and I do not know 
whether it would run under Win 98. One thing is for certain
though: The Perseus HF receiver can NOT be used under Linux.


73

Leif / SM5BSZ


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