SSTVcam, stand-alone slow-scan TV camera.

Forum for discussion of SSTV topics. Slow Scan television (SSTV) is a picture transmission method used mainly by amateur radio operators, to transmit and receive static pictures via radio in monochrome or colour.

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SSTVcam, stand-alone slow-scan TV camera.

Postby Steve Anderson » Tue Jun 07, 2022 9:07 pm

New to me, made by Argent Data Systems, price unknown. For those interested in the modes provided it could well be ideal...though not for me thank you!

Note the power voltage is 5-12V DC, but the I/O interface is 3.3V TTL.

http://wiki.argentdata.com/index.php/SSTVCAM

SSTVCam.pdf
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Re: SSTVcam, stand-alone slow-scan TV camera.

Postby Harry Dalek » Wed Jun 08, 2022 5:48 pm

Interesting but a bit more fun to make some thing than buy it premade ,has its use's i see for those that could use it i see .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: SSTVcam, stand-alone slow-scan TV camera.

Postby Steve Anderson » Wed Jun 08, 2022 6:45 pm

I agree Harry, I still have a mechanical SSTV camera on my 'TO DO' list, in the 120/128 line Cop McDonald format, I did mentioned it in the long distant past sometime....

I made a start on a 'pinhole' (no lens) version back then which should have worked in principal but finding a light sensor sensitive enough and small enough was my headache. Like many other projects it's 'on hold'.

The next time I re-visit it I'll add a lens - you can never have too much light!

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Re: SSTVcam, stand-alone slow-scan TV camera.

Postby Harry Dalek » Sat Jun 11, 2022 6:29 pm

Steve Anderson wrote:I agree Harry, I still have a mechanical SSTV camera on my 'TO DO' list, in the 120/128 line Cop McDonald format, I did mentioned it in the long distant past sometime....

I made a start on a 'pinhole' (no lens) version back then which should have worked in principal but finding a light sensor sensitive enough and small enough was my headache. Like many other projects it's 'on hold'.

The next time I re-visit it I'll add a lens - you can never have too much light!

Steve A.


That's a good project a mechanical SSTV camera ,Why not a PMT Steve ? makes it bigger but they are sensitive things and you know it would work .
I can't help my self thinking about the design problem if i were to do it i would have the framing mirror driven by a geared stepper for smooth slow movement and a polygon laser printer mirror you could in the past get them and just drive them via a square wave frequency both ideas i have used in a experimental laser NBTV projector a few years back .
Never thought of a pin hole SSTV camera ,perhaps a lot of light on the subject or test card or try it out doors sunny day of cause as i have learnt no light must enter anywhere else apart from your lens or pin hole lens in the box case what ever housing you use ,even a pin hole some where else in the case will start to wipe out the image as static snow .
Any case be interesting to see it come about and what you have come up with ,i recall you mentioning the idea some time ago .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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Re: SSTVcam, stand-alone slow-scan TV camera.

Postby Steve Anderson » Sat Jun 11, 2022 7:59 pm

Harry Dalek wrote:That's a good project a mechanical SSTV camera ,Why not a PMT Steve ?

Well, there's two reasons why I'm not going the PMT route...actually three...
1) If you recall my experiments with them some years ago I found them to be really noisy, to the extent of being unusable - perhaps I got a batch of dud ones (not from e-bay and the like, a trusted tube supplier).
2) As you want to only use part of the sensitive area of the photocathode that will make noise even worse - you only want a very small area of the projected lens image, in my case about 0.25mm square. The PMTs I used have a huge (and unused) area that simply contributes to the noise.
3) Large pulses, usually a few seconds apart from the odd Cosmic Ray that makes it past the Earth's magnetic field and atmosphere. I think that's the reasoning behind it, no matter how dark the PMT was, there were always these seemingly random pulses.

So PMTs for me at this stage are out.

So my plan (when I get to it) is to use a lens with a focal length of 100-150mm or so with an aperture of around 50mm, f2/f3 or thereabouts. Shallow depth of field, yes, but I'll live with that.

The method I used in the past was to select a jpg, then...

1) Crop/resize it to 256x256 pixels and reduce to an 8-bit monochrome TIFF file. Using Irfanview.
2) Strip off (or ignore) the TIFF header info.
3) Send that raw image data to a micro that scaled it to 128 lines, added SSTV syncs then converted it into a baseband analogue SSTV video signal.
4) Feed the whole thing into a DDS SSTV modulator and record it as a 8kHz 8-bit mono WAV file. Done.

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Re: SSTVcam, stand-alone slow-scan TV camera.

Postby Harry Dalek » Sat Jun 11, 2022 10:39 pm

PMT's I have tried ...a few different types 2 were not useable in the batch i got and were faulty pretty much ! ,and the ones i used in project cameras i found they were very sensitive to voltage like goldy locks not to little and not to much ,i was very please i made the switchable variable high negative power supply or i would of failed ,mine seemed to work between 600 and 700 volts any more it just over loaded
mmm i never noticed random pulses in mine when i was running them in powered up a light proof case but i did view results on my scope at different times of the day and it was picking up noise from the sun during day time must of been other radiation other than light and this dropped at night .
But true the PMT does not just pick up light or electromagnetic waves at that frequency but the universe pointing at it .
Going solid state a photo diode or transistor has a very tiny pickup area which i suppose could be increased or decreased with a small lens infront ,the dome sensor next size up which pretty is the above with a built in plastic fish eye lens but i think that is at a recall a very tiny solar cell device .
Good luck i will be watching ; )
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
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