The SSTV PD modes and vertical sync?
Posted: Tue Jan 04, 2022 3:45 pm
The PD modes are well-established hi-res colour modes for SSTV.
In digesting the specifications for these I notice there is no mention of vertical sync. There is mention of VIS codes, I cannot see why these couldn't replace the usual vertical sync. That assumes the VIS code is transmitted at the start of every frame, no problem there. It does possibly mean a somewhat different line (or insert shall we say) at the start of each frame, again no problem.
But so far I haven't been able to find any documented example of how this is done. I have quite a bit of data regarding this, but it's not very explicit. e.g. "VIS Codes Dayton Paper", particularly the PD section (attached).
Having downloaded a few PD mode files I was going to 'reverse engineer' these via a SSTV demodulator and 'scope and see what I might find. Though it's not the best way to get data.
Alternatively I was going to contact Paul Turner again and ask. But I'd rather not take up his time unless I really have to.
Can anyone here enlighten me? Has there been any updates to the version attached here. (Dayton SSTV forum, 20 May 2000).
Steve A.
In digesting the specifications for these I notice there is no mention of vertical sync. There is mention of VIS codes, I cannot see why these couldn't replace the usual vertical sync. That assumes the VIS code is transmitted at the start of every frame, no problem there. It does possibly mean a somewhat different line (or insert shall we say) at the start of each frame, again no problem.
But so far I haven't been able to find any documented example of how this is done. I have quite a bit of data regarding this, but it's not very explicit. e.g. "VIS Codes Dayton Paper", particularly the PD section (attached).
Having downloaded a few PD mode files I was going to 'reverse engineer' these via a SSTV demodulator and 'scope and see what I might find. Though it's not the best way to get data.
Alternatively I was going to contact Paul Turner again and ask. But I'd rather not take up his time unless I really have to.
Can anyone here enlighten me? Has there been any updates to the version attached here. (Dayton SSTV forum, 20 May 2000).
Steve A.