28-04-2018, 02:19 PM
The Stock Exchange Cable TV system I've mentioned before used computer generated text and modified domestic monochrome receivers.
The text was 30 rows of 48 characters which virtually filled the active display area (the sets were under-scanned so that all the text was visible).
The initial sets were 19" & 23" and tended to suffer badly from defocusing in the corners - particularly the 23" tubes. Later we standardised on 20" sets only.
I sometimes wondered if it might be possible to generate parabolic waveforms, similar to those used for convergence in colour sets, and use them to modulate the focus voltage in the corners although, as many tubes also suffered from severe astigmatism in the corners it probably wouldn't have been an ideal solution.
I wonder if it would have worked?
The text was 30 rows of 48 characters which virtually filled the active display area (the sets were under-scanned so that all the text was visible).
The initial sets were 19" & 23" and tended to suffer badly from defocusing in the corners - particularly the 23" tubes. Later we standardised on 20" sets only.
I sometimes wondered if it might be possible to generate parabolic waveforms, similar to those used for convergence in colour sets, and use them to modulate the focus voltage in the corners although, as many tubes also suffered from severe astigmatism in the corners it probably wouldn't have been an ideal solution.
I wonder if it would have worked?
