Very Interesting. In the WSJT user screen there are several sucessive
-19dB S/N individual listings and, out of 70 sequences, it has
selected 22 of them as being valid, but not one single correct decode.
Experience on JT65B receiving the GB3RAL and GB3VHF beacons shows
that -19dB S/N will give perfect copy, and -22dB will decode after two
or three averaging sessions, so there's something very odd going on.
What I can make out on the spectrogram, the sync tone is in
more-or-less the righ place.
Your WSPR signal is just 3 Hz low, and the JT65A sync tone about 15Hz
lower that stated, which is more than near enough for a valid decode -
and the user screen shows its doing just as it should - with some
strong enough individual demods BUT NO DECODES - why???????????????.
Do I understand you are not using the actual WSJT software to encode
the data? Are you actually sure the MultiPSK implementation is doing
its job properly.
Try WSJT 5.98
Andy G4JNT
On 22/03/2008, Graham <[email protected]> wrote:
> Ok Andy,
>
> Looks like making headway ....
>
> I'm using multipsk (the test version) which has jt65-modes .. and for want
> of a better way of describing the frequency ..sorry if it sounds a 'cb'
> like ... but .. ' The purple line' is set at the 1000 Hz mark on the
> waterfall display giving 1002 hz showing on the l/h fequency window ...as
> you say is 270 hz (ish) from the normal point ... but if you set the prog
> to that point , means you can engauge the narrow filter
>
> WSPR is running at 1500 Hz tone o/p giving 503.00 khz rf carrier frequency
>
> I though jt65 would of out performed wspr ...be intresting to see the
> parallel decodes
>
> Tnx - G ..
>
>
>
>
> ----- Original Message -----
> From: "Andy Talbot" <[email protected]>
> To: <[email protected]>
> Sent: Saturday, March 22, 2008 7:03 PM
> Subject: Re: LF: Re: Re: WSPR == ON AIR TEST NOW 1545 HRS = 503 KHz
>
>
> > Hi Graham
> > Yes, I've got the right sequence time and am running WSPR and WSJT
> > 5.98 in parallel. Surprising the WSJT averaging won't extract a valid
> > decode. Some of the sessions are being tagged as having the sync
> > detected, with a resulting 2.5kHz S/N in the --25dB ballpark, but they
> > don't want to seem to be pulled together by the averaging. The DF
> > figure is coming up as -285Hz, suggesting you're 15Hz lower than
> > advertised (should be -270Hz)
> >
> > Do have very bad QRM here. I've just gone over to th the old 137kHz
> > antenna minus its loading coil rather than the HF vertical that was
> > the existing 500kHz Rx. The LF Tee is further from the house and
> > there is about 10dB less localised E field noise. Its a pity about
> > the deliberate jamming taking place just above the upper tone
> > frequency. I'm not sure how well JT65 can cope with that.
> >
> > Update on the WSPR decodes below - it really does seem a very good
> > weak signal mode. I'm just about to write June's Data Column for
> > radcom. I'll give WSPR a section having now played with it for a
> > while in real hard off-air conditions
> >
> > Andy G4JNT
> >
> > c:\WSPR>wspr Rx 0
> > 1750 8 -17 -0.1 0.001487 G0NBD IO83 37 28.3
> > 1752 6 -18 0.1 0.001487 G0NBD IO83 37 28.3
> > 1754 5 -20 0.0 0.001487 G0NBD IO83 37 28.2
> > 1756 3 -20 0.1 0.001487 G0NBD IO83 37 28.4
> > 1758 8 -18 0.1 0.001487 G0NBD IO83 37 28.9
> > 1800 8 -14 -0.3 0.001487 G0NBD IO83 37 30.1
> > 1802 1 -24 0.0 0.001487 28.7
> > 1804 4 -20 -0.2 0.001487 27.5
> > 1814 3 -22 -0.2 0.001487 28.1
> > 1816 1 -23 -0.6 0.001487 27.9
> > 1818 4 -24 0.0 0.001487 27.8
> > 1820 7 -19 -0.4 0.001487 G0NBD IO83 37 27.4
> > 1822 3 -24 -0.1 0.001487 27.6
> > 1828 2 -24 -0.3 0.001487 20.1
> > 1830 5 -23 -0.2 0.001487 G0NBD IO83 37 27.2
> > 1832 4 -20 -0.1 0.001487 G0NBD IO83 37 24.6
> > 1834 4 -24 -0.3 0.001487 G0NBD IO83 37 21.9
> > 1836 5 -23 -0.2 0.001487 G0NBD IO83 37 22.8
> > 1842 2 -24 -0.3 0.001487 G0NBD IO83 37 23.2
> > 1844 1 -26 -0.3 0.001487 22.3
> > 1848 7 -19 -0.2 0.001487 G0NBD IO83 37 21.9
> > 1850 2 -24 0.0 0.001487 24.0
> > 1852 7 -19 -0.1 0.001487 G0NBD IO83 37 27.3
> > 1854 5 -19 -0.1 0.001487 G0NBD IO83 37 23.5
> > 1856 3 -19 -0.1 0.001487 G0NBD IO83 37 24.9
> >
> >
> >
> >
> >
> >
> > On 22/03/2008, Graham <[email protected]> wrote:
> >> Ok Andy,
> >>
> >> Thanks for taking a look , the jt65 been running for a while now , did
> >> you
> >> have
> >> the 2 systems on when you decoded the wspr signals ?
> >>
> >> jt56 is sending at even mins , check the birmingham grabber , should show
> >> the 2 tone sets
> >>
> >> Tnx
> >>
> >> Graham ,
> >>
> >>
> >>
> >>
> >> ----- Original Message -----
> >> From: "Andy Talbot" <[email protected]>
> >> To: <[email protected]>
> >> Sent: Saturday, March 22, 2008 6:17 PM
> >> Subject: Re: LF: Re: Re: WSPR == ON AIR TEST NOW 1545 HRS = 503 KHz
> >>
> >>
> >
> >
> >
> >
> > --
> > No virus found in this incoming message.
> > Checked by AVG.
> > Version: 7.5.519 / Virus Database: 269.21.8/1338 - Release Date: 3/21/2008
> > 17:52
> >
>
>
>
>
--
Andy G4JNT
www.scrbg.org/g4jnt
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