Steve Anderson wrote:
As mentioned before I intend to replace this demodulator at some point in the future, so I wouldn't worry about this too much.
Steve A.
Steve Anderson wrote:Harry, well there's not going to be a mad panic rush, so wait a while for the chips...make sure you've ordered the correct parts though. I wouldn't wait for the replacement demodulator design as that will happen after this MkIII version is complete along with the NBTV side of it. So that could be quite a way down the line.
There is also the chance that a better demodulator could be too complex and/or expensive, unlikely, but possible.
Steve A.
Yes, back in Bangkok now.
Klaas Robers wrote: (At Sat 13 May 2017, in this thread, page 1)
Yes Steve, you are right......., if the counter of the Robot 400 wasn't counting further. Let me explain:
The counter proceeds once in two lines. This is the counter for addressing the memory vertically. Each memory line is displayed twice.
268 / 2 = 138d = 86h = 1000 0110b
The bold ones can be gated out. Then on line 268 (and 269) there is the sync pulse, and
the not bold bits are don't cares, so
270 / 2 = 139d = 87h = 1000 0111b
is also gated out, so lines 270 and 271 are also giving the sync pulse. 4 lines V-sync, fine.
However...... the V-counter continues to line 312, so:
284 / 2 = 142d = 8Eh = 1000 1110b and
286 / 2 = 143d = 8Fh = 1000 1111b together,
will generate a second V-sync pulse of 4 lines, and
300 / 2 = 150d = 96h = 1001 0110b and
302 / 2 = 151d = 97h = 1001 0111b together,
will generate a third V-sync pulse of 4 lines.
The current situation is that also bit 3 is incuded in the AND , so the V-sync is only on lines 284 - 287 (second example).
So for a V-sync on lines 268 - 271 I need to include the zeros of b3 and b4 inverted in the AND. May be that, when everything is working, that I try to glue a 7402 on top of the 7430, input b3 and b4 in one of the 4 gates and connect the output to one of the non used 7430 inputs. It looks silly, but after the box is closed, nobody sees it.
Klaas Robers wrote:In the old situation the picture was shifted up to the upper edge of the TV (monitor) screen. Then the upper black and white bar was patially hidden under the bezel of the TV or monitor. You can see that in http://www.taswegian.com/NBTV/forum/viewtopic.php?f=24&t=2254&start=30. That picture is sharper. I don't know why the camera didn't autofocus better this time. But the active area is now better centered, in the vertical direction. That was the only improvement.
No, I have not seen the CQ TV magazine 136 of the BATC. Is the article on the web somewhere? I am more or less curious what they improved.....
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