[pskmail] Re: Robust psk-modes on raspberry pi

  • From: John Douyere <vk2eta@xxxxxxxxx>
  • To: pskmail@xxxxxxxxxxxxx
  • Date: Wed, 20 Nov 2013 09:17:32 +1100

There are two factors here that makeup the delay in the display of

1. The effect of the interleaver: as the encoded bits are spread over time,
the decoder has to wait to see the end of the interleaver length to decide
which bits to use.

2. The delay between the decoder thread processing and the display thread
processing. If the cpu load increases, that delay increases.

Now regarding the the slow dropoff of the signal bar. The mechanism to mark
an end of signal is only used in psk modes as we had some false positives
in pskr meaning that it would cut off in the middle of a transmission
resulting in missing characters.

Since pskr modes are almost always used in a modem situation I didn't
bother looking for a replacement.


 On Nov 20, 2013 5:16 AM, "Franco Spinelli" <frspin@xxxxxxxxx> wrote:

> Il 19/11/2013 15:25, John Douyere ha scritto:
> > No apologies needed Franco, my post here was done after your email.
> >
> > I just didn't see it before I posted in the Fldigi list.
> >
> > I just mentioned it for consistency only.
> >
> > Thanks for your help in resolving that bug.
> >
> I have applied you suggested patch to source code and now PSKXXXR modes
> decode correctly.
> In all PSKXXXR modes and in PSK63F decoding there is a delay between
> start of signal and start of characters in Rx panel.
> After start of signal level indicator go high, stay high and after 1 or
> 2 seconds text appear in RX panel. Last character decoded appear on RX
> panel 1 or 2 seconds after the end of signal and, after then,
> signal level slowly go down go reaches zero after 4 or 5 seconds
> This don't happen using PSK modes. Signal level go up and down during
> reception and go down immediatly at the end of TX.
> No difference from your simple patch (change from -127 to +127), David
> patch and your last patch as per your mail.
> This happen also on my Eeepc (Atom based). Is this correct?
> Regards
> Franco Spinelli

Other related posts: