From: Tomi Manninen OH2BNS (exbnmnd@hochtief.de)
Date: Wed Jun 13 2001 - 11:34:37 EEST
On Tue, 12 Jun 2001, Dustin Moore wrote:
> I was unable
> to get the ALSA drivers up so I don't know how those would fare. I will
> keep trying though.
The ALSA drivers can be a bit tricky to set up but not impossible. I'd
suggest you keep trying. :)
> I'm having trouble with the newqpsk modems though.
>
> The upstairs box doesn't trigger on the the tune tones of the
> downstairs box so it can't receive anything. I can see the downstairs
> machine transmitting in the o-scope window but it doesn't trigger.
> The downstairs machine, on the other hand, can hear the upstairs machine.
> It typically indicates tune tones of +/- 0.2 Hz
That means it is able to hear the tune tones long enough and to make a
"tuning decision". So that rules out any tx-delay problem. Not that there
would be a tx-delay to set in newqpsk... :-)
Are the reported tune frequencies the same for all carriers?
> and FEC errors for each channel between 40 and 85. At the end of the
The fact that you get FEC errors indicate that it was able to make a "sync
decision" and switch to data mode.
> FEC error line it reads :930/496, whatever that means.
That means a total of 930 errored bits in 496 symbols received in data
mode. Mind you you will never be able to get the error count to be zero
(unless you switch FEC off). Due to the way the framing works there will
always be some errors. But not that much obviously.
> The S/N ratios are
> from 9 to 11 for all channels. As far as I can tell my radios are running
> perfectly. The tones all sound good to me, all modems are 2500bps, 8, 3.
Hmm.. SNR of ~10 is a bit low. It's just about at the level where the
modem starts to give up. (Here one should note that the reported SNR is
more a relative figure of merit than a real S/N ratio. Getting real SNR
figures is something I still have under research...)
Are the reported SNR and FEC error figures again the same for all
carriers?
Right now I really can't think of any reason why you would get these
results. All I can think of is a problem with sound levels. Too low or too
high. One of the sound cards being way off in sample rate would also
explain it but that should show in the tune phase as uneven frequency
figures.
Also I have never tried newqpsk over FM so I don't know if there's some
issues there. But there shouldn't be as far as I can think of...
-- Tomi Manninen Internet: wzi.jlecbjs@azuma2.magma-net.pl OH2BNS AX.25: guyvgdsu.bjrzo@mail.dy.fi KP20ME04 Amprnet: terhi.victor@logonet.com- To unsubscribe from this list: send the line "unsubscribe linux-hams" in the body of a message to vhf@glen-net.ca
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