locked Re: No decode of the *.wav #IssueReport #Q65


Hi, Bill,
No WebSDR here !
Q65 is not very often in QO-100.
Most of the Signals can be easily decoded, but some NOT.
My enclosed wav files are of them.

My RX path is:
LNB, dxpatrol down converter-144MHz, FT-847, external soundcard, Raspberry Pi 4, wsjtx
My TX path:
wsjtx,Raspi, soundcard, FT-847 432MHz, dxpatrol upconverter, 5W dxpatrol PA, poty-antenna, 1m dish.
And for RX and TX a freq normal with GPS.

As I said, it works sometimes, and sometimes not.

By the way, there is the same issue with some FT-8 signals. But I think, in this case the fault is a little freq shift of the TX station.

73, Karl OE3JAG
Am 08.07.21, 12:41 schrieb Bill Somerville <g4wjs@...>:

Hi Charlie, and Karl,

that seems to confirm that the issue Karl is having is at the Rx end of the link. Karl are you using something like a WebSDR to receive signals? If so then that is certainly where the excess delay is being added.


On 08/07/2021 11:09, Charles Suckling wrote:
Hi Bill

I believe the QO-100 transponder is of the bent-pipe variety, ie  it is basically a mixer.  

When sending myself various WSJT-X modes early on, I remember DT being in the 0.3s region (using an analogue receiver with minimal latency).  


Charlie G3WDG

On Thu, 8 Jul 2021 at 11:17, Bill Somerville <g4wjs@...> wrote:
Hi Karl,

I can only assume that the delay when  receiving signals via QO-100 is mostly artificial. The propagation delay for the round trip to a geostationary orbit satellite is less that 250 mS. Perhaps there is a considerable store and forward delay in the transponder logic of the bird and that combined with the propagation delay and any latency in your receiver is exceeding the DT search range of WSJT-X for Q65-15 signals.


On 08/07/2021 08:13, Carlos wrote:
Hi, Bill,
Thanks a lot, but worth mentioning is, that some times it works.
Maybe in this case, the SAT delay is critical under the DT limit.
Anyway, Q65 is basicly not done for SAT communication, so this is not an urgent case. I just wanted to report !
TU all, 73, Karl OE3JAG
Am 07.07.21, 20:47 schrieb Bill Somerville <g4wjs@...>:
Hi Karl,

apologies, I see that enabling the decode after EME delay option does not help with your .WAV files from QO-100 QSOs.


On 07/07/2021 19:31, Bill Somerville wrote:
Hi Karl,

I believe Joe was simply demonstrating the issue rather than proposing a solution for all. I would guess that the QO-100 transponder has some delay and that plus the propagation delay for two times the distance to the satellite geostationary orbit location is more than the upper limit that the Q65 decoder searches for candidate signals. Try checking the "Settings->General->Decode after EME delay" option.


On 07/07/2021 19:12, Carlos wrote:
Dear Joe,
I feel much appreciated by your answer yourself ! TU !

> A special build of WSJT-X 2.5.0 that extends the upper DT limit to 1.5 s

But, sri, I do not know how to do this special build ?

I have a raspberry 4b, raspibios buster.

TU, 73, Karl OE3JAG

Am 07.07.2021 um 18:42 schrieb Carlos Dentrix:
Am 06.07.21, 22:51 schrieb Joe <joe@...>:
On Tue, Jul 6, 2021 at 10:10 AM, Carlos wrote:

Dear developer team !

The enclosed Q65 WAV files, recorded via SAT QO-100 are NOT decoded.
Neither by V.2.4.0 nor by V.2.5.0-rc3 now.

What is the reason ?
light frequ.shift ?

TU for answer, this decode problem occurs often on SAT.
73, Karl OE3JAG
The 15-second Q65 submodes search for synchronization over the range -1.0 <= DT <= 1.0 s.  The signal in your .wav files has DT somewhat larger than 1.1 s.  A special build of WSJT-X 2.5.0 that extends the upper DT limit to 1.5 s yields the decodes for your files shown below.
                -- 73, Joe, K1JT

184700 -5 1.1 1824 : CQ EA2AA IN83  q0

184730 -6 1.3 1831 : OE3JAG EA2AA RR73  q0

184830 -6 1.1 1824 : OE3JAG EA2AA 73  q0

185000 -2 1.1 1824 : TU KARL  q0

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