5.7DATV

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radiogareth
Posts: 1370
Joined: Wed Jan 06, 2016 9:46 am

5.7DATV

Post by radiogareth » Mon Jun 03, 2024 12:54 pm

Can anyone with rx capability on 5.76GHz check that DATV Easy driving a PLUTO produces working video on that frequency (ie decoded a picture)?
I get very fast lock with all the Data info coming up, but NO PICTURE.
I'm down-converting to 3.4GHz then using an Ionica front end to downconvert to 920MHz (Modified Ionica) then into a Picotuner.
Direct 3.4GHz (ie 9cms) gives almost instant lock and picture (for 9cms) but the TX source there is PD4 driving a Pluto at 3.4Ghz.
Wondering what's going on as the signal 'look' fine on the analyser.
Gareth

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ON1AVO
Posts: 41
Joined: Sun Nov 20, 2011 2:35 pm

Re: 5.7DATV

Post by ON1AVO » Mon Jun 03, 2024 5:41 pm

Gareth,

I can confirm DATV Easy v3.08 works on 5760 MHz. See screenshot.
Used 6CM convertor: FPV Rx module with IF 480MHz => Minitioune, MER not great.
5760MHz RX (small).png
5760MHz RX (small).png (367.12 KiB) Viewed 2248 times
73 de ON1AVO
Freddy
73 de ON1AVO
Freddy

G4NZV
Posts: 37
Joined: Wed Mar 24, 2021 8:35 pm

Re: 5.7DATV

Post by G4NZV » Mon Jun 03, 2024 6:28 pm

Hi Gareth,
My guess is the IQ is swapped due to an extra mix in your downconverter process. To prove try sending a DVBS DATV signal and see if video can be seen properly. Remember DVBS2 does not work with a frequency inversion or IQ the wrong way round. Think of it as trying to listen to Upper Sideband signal using Lower Sideband setting on your receiver.
Another test of your system:
SDRAngel has the ability to swap IQ over when receiving DVBS2 and other signals. In Device Type press the Delta Frequency X then press the IQ button then OK.
73 Steve G4NZV
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SDRangel IQ swap.PNG
SDRangel IQ swap.PNG (37.62 KiB) Viewed 2236 times

radiogareth
Posts: 1370
Joined: Wed Jan 06, 2016 9:46 am

Re: 5.7DATV

Post by radiogareth » Mon Jun 03, 2024 7:00 pm

Thanks Freddy and Steve, firstly that the TX stream is probably OK and secondly that might well be the issue. I never really gave it any thought as I have previously lashed up a similar system but used a Titanium C band LNB as the second IF/down-converter. Maybe that inverts anyway as the LO is high side.....out of my depth here...you can tell ;-)
I'll do some tests....DVBS will be fine for the weekend after all, its only contest numbers :-)
Gareth

radiogareth
Posts: 1370
Joined: Wed Jan 06, 2016 9:46 am

Re: 5.7DATV

Post by radiogareth » Mon Jun 03, 2024 7:46 pm

Hmmm, same behaviour, quick lock on the header info, no video forthcoming.....but DATVEasy 3.08 on my laptop gives two green 'leds' but no kb/s, despite a full uninstall and reinstall.Sending something but maybe no picture info.....yet to try SDRAngel...tomorrow, I'm done-for today....
Gareth

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