View Single Post
Old 21st Mar 2019, 12:26 am   #145
1100 man
Octode
 
1100 man's Avatar
 
Join Date: Apr 2016
Location: Ventnor, Isle of Wight, & Great Dunmow, Essex, UK.
Posts: 1,377
Default Re: Hedghog standards converter

Quote:
Originally Posted by Lloyd 1985 View Post
I did notice the vertical jittering on the test card on the first Hedghog, the one with the latest FW, which was not present on normal video, didn’t notice it on the second one, but I’ll have to check again to be sure. The TMB272 didn’t like the equalising pulses, they make the picture drop down about an inch.
Congratulations, Lloyd!! I'm glad they worked after all that waiting!

It would be interesting to compare the jitter on the test card between the two firmware versions.

I've just had a further look at mine with regards to the jitter. As Lloyd said, it's either not there or not noticeable on actual video, but is very noticeable on the test card.

If I turn off the equalising pulses, I can carefully adjust the frame hold so that it goes completely out of interlace. At this point there is no vertical jitter and the picture is rock steady. As soon as the picture interlaces, that's when the jitter starts.

Also, as I mentioned before, the setting of the line hold is critical or the LOPT clatters away at 50Hz!

The same set fed with test card C from the Aurora gives a rock steady picture with no jitter at any setting of the frame hold. You can wind the line hold nearly end to end before it goes out of lock and at no point do you get the 50Hz chatter from the LOPT.

I tried a different TV with flywheel sync. There was (understandably due to the flywheel action) no clatter from the LOPT but the vertical jitter was just as bad. In fact, with the equalising pulses on, at some settings of the frame hold, I could get a good 1/2" of jitter!

I took a picture of the test card, but obviously this won't show the jitter!

All the best
Nick
Attached Thumbnails
Click image for larger version

Name:	DSCN0811.jpg
Views:	146
Size:	75.0 KB
ID:	180274  
1100 man is offline