acl wrote:Hi Steve, Any progress on SSTV lately? Regards Chris Lewis
Well. yes and no. I've produced a couple of up-converter designs which are simpler than the first version a few years back. One is basically the same, SSTV to 625, the other SSTV to 800x600 VGA. It might be possible to combine the two and have a selectable output standard. But that's not a priority at the moment. These days the VGA version is probably more useful....VGA is the same in the US as the EU.
As before these are for the original Cop McDonald standard, a 1:1 square aspect ratio, monochrome, 120/128 lines at either a 15Hz or 16.7Hz line-rate, often called the 8-second mode.
Most of the simplification is in the area of the RAM, two 8-pin serial RAM chips instead of a 28-pin (or more) parallel version. This also reduces the pin-count on the two processors to 28-pin 0.3" devices. One might become a 20-pin device.
They are just paper/software designs at the moment, I've yet to plug the soldering iron in.
There is also a possible upgrade to the SSTV demodulator. Although technically an improvement, I somehow doubt this will be visible on-screen. It is also somewhat more complex using an FIR subcarrier filter. Though just the FIR filter alone IS a worthwhile improvement. The other changes are subtle and may not be noticible.
Steve A.
After that a JPG-to-SSTV device would be useful, but this is probably better/easier(?) done on a PC. But not by me, I've not written code for a PC before, and I don't intend to start now! The original JPG-to-SSTV version (not published) involved a number of manual steps to get the original JPG configured acceptable for conversion to SSTV and subcarrier modulation.