Is the SDRplay a good approach for recording PAL signals?

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Spiller
Posts: 2
Joined: Sat Nov 26, 2016 2:28 pm

Is the SDRplay a good approach for recording PAL signals?

Postby Spiller » Sat Nov 26, 2016 2:46 pm

Background
My family have a lot of old video recordings on VHS tapes which we would like to digitialize for the sake of preserving their content. I do have one of those USB tuners made for this, but I'm not satisfied with the output and since I have worked with image restoration I want to try to develop something better.

What I want to do is to get as close as possible to the signals on the tape. This is in order to:

  1. Better understand how errors occurs in recordings
  2. Avoid the constraint of having to process the signal in real-time
  3. Fix errors before they have been processed and become hard/impossible to fix

I believe this can open up for a lot of possibilities for improving the quality of the recording and restorative work. For example I want to see if it is possible to fix broken tracking by recording it multiple times with different tracking offsets and merge them on a line-per-line basis.

However while I'm pretty confident I can develop the software (a bare bone version at least) I have very little experience with electronics and thus no clue on how to best get the signals into my computer.
I'm probably looking after something like a digital oscilloscope and record the signals directly from the heads, however something which can handle a 8 MHz signal continuously appears to be pretty expensive. So I'm wondering if I could use a SDRplay to pick up the antenna signal from the VHS player somehow.

Questions
  • Is the SDRplay a sensible approach to record PAL signals from a VHS player?
  • What kind of setup would I need to have to transfer the signal from the VHS player to the SDRplay?
  • How much quality degradation of the signal should I expect?
  • Is there some cheaper or better approach than SDR that I'm overlooking?
Last edited by Spiller on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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DanubeBCL
Posts: 180
Joined: Sat Jul 02, 2016 12:39 pm

Re: Is the SDRplay a good approach for recording PAL signals?

Postby DanubeBCL » Thu Dec 01, 2016 10:07 am

Maybe I have not fully understood your intention and what you want to do with the IQ baseband spectrum you can record with SDRuno.
I have digitialized a lot of old VHS videos with a frame grabber (an old Terratec Grabster AV 300 MX taking up the S-video output of my old VHS machine) and the free Virtualdub software. In the meantime I have addionally purchased an external timebase corrector CTB-100 which restores the sync pulses which are often missing in old worn out VHS tapes. I have never spent any thoughts on how the spectrum/waterfall of the S-video signal might look on an wideband SDR.
73, Heinrich

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Spiller
Posts: 2
Joined: Sat Nov 26, 2016 2:28 pm

Re: Is the SDRplay a good approach for recording PAL signals?

Postby Spiller » Thu Dec 01, 2016 10:36 pm

Basically I want to do the same functionality as your Terratec Grabster AV 300 MX but in software. I want to see how much I can improve image quality by using of state of the art image restoration techniques (stuff like statistical models and artificial intelligence). You can look at it as a hobby research project.

While SDR seems a bit of a roundabout way of doing it, I don't have the electronic knowledge to build something like that and from what I understood digital oscilloscopes with specs like that are too expensive for initial experiments. Maybe there is something else out there I could use which I don't know about?
Surely it should be possible to attach an amplifier+antenna to the VHS player and pick it up with the SDRplay, though I wonder if it is possible to avoid having to use antennas to transmit the signal, and if it is possible to entirely avoid the extra modulation as the SDRplay can go pretty low frequency.
Last edited by Spiller on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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