There are a few other very knowledgible resources with NTSC on this forum that should be able to help you with specific questions. What are you trying to do?
Some say it is 63.5 uSec over about 20 lines. Most do not draw it as one long pulse but a series of pulses that seem to be 31.8 uSec. Would one long pulse do the trick.
"The serrated vertical pulse consists of six individual pulses, each of approximately 27us."1
These pulses get integrated after the Sync Separator, the resulting output is a triangle wave [noparse][[/noparse]sawtooth], at or near 60Hz (in North America.)·
"Generally, the vertical hold control sets the oscillator at 50-59Hz, to be locked in sync at 60Hz at the time of the third or fourth division (serration) of the vertical sync.· The main requirement for timing is that the triggering occur at exactly the same time of the vertical sync pulse for every field." Ibid.
1 "Basic Television Principles and Servicing", Bernard Grob, 4th Ed., 1975
RickJ said...
Would one long pulse do the trick.
UPDATE -- It could be that the latest receivers (TVs) don't need/use the RC integrator and the resulting sawtooth waveforms as we did in the·"days of yore" as·they may be able to acquire/lock a lot faster and maybe start a counter or one-shot from the get-go.· Older models will be expecting the serrated pulse (it's 6 of them in rapid succession.)
Post Edited (PJ Allen) : 6/16/2007 11:48:41 PM GMT
Thanks. I looked at the code today on the "Build Your Own Games Console" CD.
I do not see the location of the serated pulses yet.
The code is not hard to read and·it does have three sections for Vertical Blanking.
I can only assume that is what is going on.· I need to hook it to an O-scope when I get it built. ·Good day.
RickJ
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http://www.rickard.gunee.com/projects/video/sx/gamesys.php
There are a few other very knowledgible resources with NTSC on this forum that should be able to help you with specific questions. What are you trying to do?
Thanks
190-usec
These pulses get integrated after the Sync Separator, the resulting output is a triangle wave [noparse][[/noparse]sawtooth], at or near 60Hz (in North America.)·
"Generally, the vertical hold control sets the oscillator at 50-59Hz, to be locked in sync at 60Hz at the time of the third or fourth division (serration) of the vertical sync.· The main requirement for timing is that the triggering occur at exactly the same time of the vertical sync pulse for every field." Ibid.
1 "Basic Television Principles and Servicing", Bernard Grob, 4th Ed., 1975
UPDATE -- It could be that the latest receivers (TVs) don't need/use the RC integrator and the resulting sawtooth waveforms as we did in the·"days of yore" as·they may be able to acquire/lock a lot faster and maybe start a counter or one-shot from the get-go.· Older models will be expecting the serrated pulse (it's 6 of them in rapid succession.)
Post Edited (PJ Allen) : 6/16/2007 11:48:41 PM GMT
I do not see the location of the serated pulses yet.
The code is not hard to read and·it does have three sections for Vertical Blanking.
I can only assume that is what is going on.· I need to hook it to an O-scope when I get it built.
Post Edited (RickJ) : 6/17/2007 5:36:58 AM GMT