SSTV Today (80s Newsletter)

[BruXy]

Two numbers can be found here:

https://archive.org/search?query=creato ... V+Today%22

Hopefully, more scans will appear.

Volume I, Number 4 -- nice article about the Robot Color system (Y, R-Y/B-Y) and experiments on Oscar 10.
Volume II, Number 7 -- Dayton 1984.

I had never seen this newsletter before, but I was quite surprised at how many names I remember from the 90s "Hamcomm SSTV era" who were involved in earlier computer SSTV with TRS-80 or other products.

[Steve Anderson]

Two numbers can be found here: Hopefully, more scans will appear.

Yes, I hope so too. We'll see...

In the meantime I'm pulling together my next iteration of a SSTV-to-625 monitor adaptor. It was originally going to be SSTV-to-VGA (800x600), but each pixel becomes 25ns, getting RAM of that speed here isn't easy. Though in the UK the usual suppiers have RAM with a 10ns speed rating, I'll leave that for the day I really need it. Plus even a mediocre 625 monitor/TV is good enough for the original 120/128-line monochrome SSTV display specification. Colour too, I may have a go at that in the future...the inspiration for that was Bruxy's link above.

If I adopt one (or more) of the SSTV PD colour/hi-res modes [Note 1} that's when the motivation will come about.Though I will always have a 'soft-spot' for the original Cop McDonald monochrome version...the attraction is its simplicity....and speed...

Steve A.

Note 1: I assume that the Robot colour modes were similar to the PD specification, they may or may not be, more research needed....yes, I'm new to colour SSTV...but I'm not going to jump down the colour rabbit-hole quite yet...I'm still not convinced it's worth it...though it would be an interesting engineering exercise to do so...

[BruXy]

Hi, yes PD mode uses the the same color representation as Robot:

https://digitalradio.groups.io/g/main/t ... ns/3926706

About Y/R-Y/B-Y:
https://web.archive.org/web/20041029075 ... C_CODE.htm

I also tried to describe it here in section 3.5.2:
https://sstv-handbook.com/download/sstv_03.pdf

[Steve Anderson]

Thanks BruXy for those links, I'll have to spend some time studying them, there's quite a lot of data to absorb. I'm bound to come up with some questions, so be prepared!

I think the first area of attack for me will be the colour matrixing, the addition, subtraction and multiplication as shown in the links above...and ensuring that the chosen processor is up to the task or use look-up tables. I'm assuming that the input values are all 8-bit and signed where needed, a total of nine bits? Rounded/truncated while preserving signs also.

Steve A.

[Steve Anderson]

I'm not sure if I want to go down the colour/hi-res/PD modes route quite yet, I may do one last SSTV-to-(625 or VGA) monochrome Cop McDonald up-convertor...basically taking advantage of newer serial RAM devices. All in preparation for whatever may come next...but serial RAM at VGA speeds may be pushing it a little to far. I haven't sorted our the timings required yet....a little more time required....plus there is the issue of D-A speed to consider...

Steve A.