Analog ATV - Sync generation

[DL5BCA]

Hello,
We still do a lot of analog ATV here.
The TVs only display a picture if there is a good synchronization pulse.
Somewhere there was a circuit/device that generates the synchronous pulse and displays the existing video signal.
Even if only noise is received.

Does anyone know where I can buy this?

[PA3CRX]

It only needs line sync pulses to 'open' the screen for noise.
You can make a simple 15.625 Hz generator and add that signal to your noise.
However, if some (noisy) image is received, you want to have that added line sync synchronised with the received picture.
PA0JBB made such a circuit and PE1RQM described the circuit and some modifications on his website: https://www.pe1rqm.nl/video-sync-genera ... monitoren/
With some video's he demonstrates what the result of the circuit is.
He developped it even further with some DSP circuit.

Good luck!
Chris PA3CRX

[DL5BCA]

Hello Chris
thanks for the hint.
I have already found this page and the further development.
Unfortunately, the DSP Syncmurf 5 is no longer available.
However, I wrote to the OM, perhaps there are still boards to be found.

[PA3CRX]

Otherwise build the circuit on experimenters board?

blue screen killer.JPG (1.23 MiB) Viewed 39405 times

I was thinking about making the pulse with a NE564 to ‘open’ the screen and as soon some sync is detected to have it locked to the incoming circuit..

Or maybe something with an Arduino and a LM1881?

Good luck,
Chris PA3CRX

[DL5BCA]

Hello Chris,

thank you for your ideas.

I need 3 of them. This is complex with a experimenters boards.

I'm currently creating a new repeater control and I'm using a Blackmagic ATEM Extreme to mix the audio/video signals. Therefore, the AV video signal must be converted to HDMI. I'm currently testing a few converters, they all behave differently with noisy images (so far I've tested four different converters from different manufacturers).

That's why I thought that if the synchronous pulse is there, the AV-HDMI converters would at least have to convert a noisy image.

Somehow I had a finished product - in an orange case - in my memory. This may also come from the FPV area (drones).

I'll keep looking there.

[M0DTS]

The Eachine Pro DVR recorders do this but if I remember correctly they leave logo's on the screen all the time...

I tried many AV>HDMI converters but they all have flaws.
For GB3KM AV to HDMI inputs I used a raspberry Pi with EasyCap dongle and vlc player.
If you have supply of the original UTV007 dongle then it will show weak signals into the noise too.

Rob

[DL5BCA]

Hello Rob,

yes, I had the DVR recorder in mind. However, having graphics in the picture is stupid.

I also considered Raspberry with Grabber.
But the repeater switches off the transmitters/receivers after 10 minutes of inactivity to save power.
Then 3 Raspies would have to keep running, which isn't that effective in the long run.

Then I guess I'll have to search a little further.

Thank you for your effort.

[gw6bwx]

Perhaps this is what you are looking for:
http://www.atv-projects.com/50p_SPG.html

Brian.

[PA3CRX]

Nice circuit!
It could also be done with an Arduino (viewtopic.php?f=2&t=6592 ).
However, the sync pulses needs to be synchronised with the incoming signal.

[g8lce]

My post about AMX DVX 3155HD and the similar 21XX might be useful.
These devices can take in composite video as well as HDMI etc. and give a locked output. They can be bought for around £40 if you look on Ebay but cost £1000's when new. They could be programmed to use the digital sensing inputs and relay outputs too.
viewtopic.php?f=15&t=8690
Some other DATV users have been impressed by what they can do.

Martin G8LCE