Klaas Robers wrote:Steve,..I still don't know what you did in your demodulation channel.
Ah! Until I'm sure that I've got this right I'm keeping quiet on how I'm doing this. As I said before, it has probably been done previously though I've never seen any reference to it. It's no Earth-shattering modification of the Laws of Physics, just an idea I had after seeing the circuit diagrams of your 1973 SSTV monitor...40+ years later.
But I have to admit defeat in my aims to reduce the chip and pin-count. It's not excessive and on a par with the complexity of the robot 70 design, though maybe with further effort it could be simplified without compromising performance.
The headache is the sync detection performance, if you don't mind the 'jitters' then it's just two 8-pin chips and a handful of passives...as per previous screen-shots. On a small screen you may not even notice the 'jitters', but on a medium-sized TV you sure do! On a small screen you're unlikely to notice the improved resolution too.
As of this evening I'm off to Changsha in China.
Steve A.