Retro SSTV Anyone? II

Where it all started as far as most are concerned and saw heavy use from the 60s through to the 80s. Colour and Hi-res modes have unfortunately pushed this system into the backwaters of SSTV. Time to resurrect interest in this simple analogue system.

Retro SSTV Anyone? II

Postby Steve Anderson » Wed Feb 22, 2017 6:46 pm

A refresh of the previous thread as it had become long-winded. I plan, like Andrew in his NBTV monitor build, to create a separate thread for the SSTV-625 up-converter design and construction.

Here it's now primarily about the basics of the standard and the basics of what others have done in regards of the original 120/128-line monochrome SSTV system. If you wish to add details of what you have done, what you built and what its status is today, I suggest kicking off a new thread as I will do for the SSTV-625 up-converter.

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Re: Retro SSTV Anyone? II

Postby Harry Dalek » Wed Feb 22, 2017 10:51 pm

Steve Anderson wrote:A refresh of the previous thread as it had become long-winded. I plan, like Andrew in his NBTV monitor build, to create a separate thread for the SSTV-625 up-converter design and construction.

Here it's now primarily about the basics of the standard and the basics of what others have done in regards of the original 120/128-line monochrome SSTV system. If you wish to add details of what you have done, what you built and what its status is today, I suggest kicking off a new thread as I will do for the SSTV-625 up-converter.

Steve A.


It took a while and a lot of help from Andrew but i made it ,...Steve how good is this a real place for SSTV for some reason its never really had a home any where apart from perhaps Face book on modern current systems .
Retro SSTV perhaps the odd web page but can not say till now there has been a Forum for it but great to have a place for it hope we have some extra disciple's :wink:
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: Retro SSTV Anyone? II

Postby Harry Dalek » Wed Feb 22, 2017 10:58 pm

OH i was thinking we should also have a topic here to place sound files that can be used for those testing monitors and software so vintage SSTV programs are not lost as web pages with them lapse...
i also have stuff scattered on the forum i would not mind placing here instead of in the off Topic area .
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: Retro SSTV Anyone? II

Postby Andrew Davie » Wed Feb 22, 2017 11:05 pm

Harry Dalek wrote:OH i was thinking we should also have a topic here to place sound files that can be used for those testing monitors and software so vintage SSTV programs are not lost as web pages with them lapse...
i also have stuff scattered on the forum i would not mind placing here instead of in the off Topic area .


Just PM me or a moderator and we should be able to move things.
For moderators' reference, at bottom-right of any topic thread there is a "Quick-mod tools" menu. From that menu you can select "move posts" and then GO
That takes you to a selection page where you select posts and their new destination
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Re: Retro SSTV Anyone? II

Postby Harry Dalek » Wed Feb 22, 2017 11:22 pm

Andrew Davie wrote:
Harry Dalek wrote:OH i was thinking we should also have a topic here to place sound files that can be used for those testing monitors and software so vintage SSTV programs are not lost as web pages with them lapse...
i also have stuff scattered on the forum i would not mind placing here instead of in the off Topic area .


Just PM me or a moderator and we should be able to move things.
For moderators' reference, at bottom-right of any topic thread there is a "Quick-mod tools" menu. From that menu you can select "move posts" and then GO
That takes you to a selection page where you select posts and their new destination


For sure i would like this one moved here
viewtopic.php?f=8&t=1318&hilit=mechanical+sstv+steps
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: Retro SSTV Anyone? II

Postby Andrew Davie » Wed Feb 22, 2017 11:29 pm

Harry Dalek wrote:[
For sure i would like this one moved here
viewtopic.php?f=8&t=1318&hilit=mechanical+sstv+steps


By "here" I have assumed you meant to the SSTV forum, and so it is done.
Easy to move anywhere, so let me know if it's OK or not.
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Re: Retro SSTV Anyone? II

Postby Harry Dalek » Thu Feb 23, 2017 10:22 am

Andrew Davie wrote:
By "here" I have assumed you meant to the SSTV forum, and so it is done.
Easy to move anywhere, so let me know if it's OK or not.


Yes Andrew i see that worked Thanks
I will have a look and see if i have other stuff
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: Retro SSTV Anyone? II

Postby Andrew Davie » Fri Apr 07, 2017 5:23 pm

Steve Anderson wrote:Well, the board layout implications of the posting above are more than I expected! In a positive manner. I may shuffle things around to reduce stray capacitance. The differences between the MkI version and this MkII version are plain to see. MkI on the left, MkII on the right.

But before I get carried away I MUST work on the timings - something for the weekend.

Now the question is where do I place this thread? It's both NBTV and SSTV.

Steve A.

Sorry, pdf for reasons mentioned above. I'm waiting for my Acad expert to return from Malaysia, late this evening I think.



You could just do a screen grab. On OSX it's SHIFT+COMMAND+4 and you mark the area to grab and it's stored automatically as a file on your desktop.
For windows the solution is to get OSX ;)
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Re: Retro SSTV Anyone? II

Postby Steve Anderson » Fri Apr 07, 2017 6:13 pm

Andrew Davie wrote:For windows the solution is to get OSX ;)

Ah yes! I would. There's more than one Mac device in this house, but...a lot of the software I use isn't written for Mac. AutoCad, which started out as a Mac application (1980s) has only last year been available in a Mac version again. A hiatus of over 20 years.

Other software I use like circuit simulation isn't written for Mac. There are alternative Mac versions, sure, but they're expensive. Not only that but clients invariably specify the output must be in a Windoze compatible format. So as the US might say, "I'm stuck between a rock and a hard place."

More correctly a client uses a Win app which isn't available on other platforms so I have to use the Win version. The penetration in Asia of Mac is far less than the west, but that appears to be slowly changing. The reason we DO have Macs in this house is that my niece who lives here works in an iStore!

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Re: Retro SSTV Anyone? II

Postby Klaas Robers » Tue Apr 11, 2017 10:54 pm

This weekend I was at the NBTV-Convention, held in Eastwood Nottingham. I went by car/ferry at friday, stayed at the friendly home of Chris and Pam Lewis in Loughborough, visited the Convention in Eastwood at Saturday and drove home during the night, from 17.00 to 03.00..... pffft.

I had taken my Heathkit like SSTV monitor to show, while Chis showed his little B&W Arduino based SSTV camera and his Raspberry Pie display. We tried to connect both setups, but that failed because of incompatibility of cables, plugs and systems. The things Chris made work only after a VIS code and the camera sends only one frame and then stops. Then it has to be reset and after some 10 seconds a new frame started sending.

Chris gave me two older books on SSTV, one of them written by Grant Dixon, the man that involved me in the club. Then I found out how chaotic SSTV became and why I left it just in time. It became obvious for me that different individuals and companies developed a multitude of incompatible systems and modes, such that all users had to buy all their new "products". During that process the system moved steady away from the area of television, into the direction of facsimile, where it takes many minutes to send one photo. Sending a .jpg would have been a much better idea. Yes, now.

It looks to be a good idea of you, Steve, to keep away from this chaotic mess and return to the source, where it is difficult enough to come to a good working system. So, lets work into that direction.
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Re: Retro SSTV Anyone? II

Postby Harry Dalek » Tue Apr 11, 2017 11:32 pm

Klaas Robers wrote:This weekend I was at the NBTV-Convention, held in Eastwood Nottingham. I went by car/ferry at friday, stayed at the friendly home of Chris and Pam Lewis in Loughborough, visited the Convention in Eastwood at Saturday and drove home during the night, from 17.00 to 03.00..... pffft.

I had taken my Heathkit like SSTV monitor to show, while Chis showed his little B&W Arduino based SSTV camera and his Raspberry Pie display. We tried to connect both setups, but that failed because of incompatibility of cables, plugs and systems. The things Chris made work only after a VIS code and the camera sends only one frame and then stops. Then it has to be reset and after some 10 seconds a new frame started sending.

Chris gave me two older books on SSTV, one of them written by Grant Dixon, the man that involved me in the club. Then I found out how chaotic SSTV became and why I left it just in time. It became obvious for me that different individuals and companies developed a multitude of incompatible systems and modes, such that all users had to buy all their new "products". During that process the system moved steady away from the area of television, into the direction of facsimile, where it takes many minutes to send one photo. Sending a .jpg would have been a much better idea. Yes, now.

It looks to be a good idea of you, Steve, to keep away from this chaotic mess and return to the source, where it is difficult enough to come to a good working system. So, lets work into that direction.


Sounds like fun and games Klass feel sad you could not hook your monitor up to chris's camera ....
What ended up called SSTV these days is what put me off later SSTV no direction evolution gone mad in different directions which can only end up in one way all the systems being killed off by each other where no one can home brew a device not really when its a computer needed to view the system in the first place and going to the point where its just file being sent ...all good and well but thats not SSTV any more .
Analog is where i would rather stay
Least with facsimile you can still make a device with no computer needed to record the image..i sort of feel we should of had a topic for this one as it did start every thing ...
Sometimes its nice to stick with the simplest way to do the the same thing you can have a computer with software press a button theres your image next to it some thing you have made flick a switch you have soldered in place same result but satisfaction :!:
Attachments
Screen 00007.jpg
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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: Retro SSTV Anyone? II

Postby Steve Anderson » Thu Apr 13, 2017 4:40 pm

I've moved the two posts referring to the SSTV/NBTV MkII up-converter to the correct thread.

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Re: Retro SSTV Anyone? II

Postby Klaas Robers » Fri May 05, 2017 12:28 am

I restored the large circuitdiagram of the Robot 400 scanconverter to one document. It is attached as .pdf, but this .pdf is in A3 size. This is rather difficult to read, so I had it printed in A2 size and the clipped off some blank on the top and more blank at the bottom. Now for storage, when zig-zag folded it has the size of A4, but when unfolded almost 3 times as wide. If you have good eyes, you can do with printing on A3.

There have been several improvements/changes during the life of the 400, see the notes for C and D at the right edge of the diagram. My Robot 400 has a C-version PCB.
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Circuit diagram of Robot 400, D-version
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Re: Retro SSTV Anyone? II

Postby Steve Anderson » Fri May 05, 2017 2:31 pm

Good job done there by pasting it all back together Klaas. I wonder what size it was printed originally? Assuming it was a single sheet. Being a US product it wouldn't have been one of the 'A' series (A4 etc.).

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Re: Retro SSTV Anyone? II

Postby Klaas Robers » Fri May 05, 2017 7:05 pm

Steve, afterwards the person that I bought the Robot 400 from, found back the original circuit diagram and sent that to me. It has the width of A3 in landscape and is rather difficult to read. I think that was the original size, but my A2 is better readable.

This original diagram is of the first version, not the A, B, C or D successor. There are missing parts, that are on my D-diagram and that are too on my PCB. One of the later added parts is the second opamp U92 in the input amplifier and the two diode input limiter; and at the SSTV output the SINE circuit. Originally the Robot gave an triangular output signal from the 566 oscillator (U89). I think that the four diode circuit is there to clip off the sharp max. and min. points of the wave form. However I can't see that happening in the output signal.

I think that I have a problem in one (or two) of the memory chips, as I see in the grey scale, which is generated digitally (U72) and stored immediately in the memory, bright vertical lines that are obviously not as it should be. The problem is that the data in the memory is in gray-code, which is converted to binary by U85 for fast-scan and U86 for SSTV, prior to D-A conversion. That gray code makes it difficult to predict what is going wrong.

I more and more get the idea that the Robot is designed for 120 lines and the extra 8 lines is only there , because the memory space was any way available. I have to see what number of lines is outputted in the SSTV signal. I guess it is 120 lines. This information can help you in the design of your scanconverter, isn't it ?
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