04-09-2017, 05:51 PM
I had thought that in the 405 system that black level was always at the same level as blanking level, but in post 32 in this thread over on UKVRRR there is a image from Wireless World 1956 and in it it states that black level has changed from 30% to 35% of peak white with blanking level remaining at 30%.
I have build into the converter a switchable pedestal which lifts black level from 300 mV above sync tip to 350 mV. When the pedestal is switched in the video is scaled to accommodate it.
I have tried it out on my Bush TV24 which dose not have fly back blanking and the pedestal dose help. It dose not eliminate the fly back lines but dose reduce there intensity.
Photos below is with no video present. First is of a trace without pedestal and the next is with the pedestal. The third is of the TV24 without pedestal and the last one is with pedestal.
Frank
I have build into the converter a switchable pedestal which lifts black level from 300 mV above sync tip to 350 mV. When the pedestal is switched in the video is scaled to accommodate it.
I have tried it out on my Bush TV24 which dose not have fly back blanking and the pedestal dose help. It dose not eliminate the fly back lines but dose reduce there intensity.
Photos below is with no video present. First is of a trace without pedestal and the next is with the pedestal. The third is of the TV24 without pedestal and the last one is with pedestal.
Frank
