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artis
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I had a talk with a friend of mine , just wanted to make sure I'm not wrong.
I actually have one older CRT set with an open back in another room so I went to check my "question" out a bit before asking.
1) Is it right that the video signal (after some input demodulation etc boards) directly then goes and controls the cathode ray electron gun?
2)Am I right in assuming that the deflection coils only move (raster) the electron beam across the screen to form horizontal lines/retrace as well as perform vertical retrace of the beam diagonally in order to start a new frame while the exact pattern in which the electrons from each of the 3 guns (color tv)or single gun(black&white) hit specific spots/pixels on the screen in each horizontal line is controlled by the video signal in the electron gun?
3) If I had a single white stripe vertically in the midst of my screen does that mean that in a single frame in each of the horizontal lines the electron gun would only fire at the moment which coincides with the time when the beam is at the mid position?
4) Would it be fair to say that the way in which a video signal controls the control grid of a CRT electron gun is very similar if not exact to the way an audio signal would control the grid of an audio amplifier vacuum tube ? in an audio tube there is considerable idle bias current to achieve linear operation and minimize crossover distortion, what happens within a CRT electron gun in this regard ? I would tend to think that the crt's electron gun is much more nonlinear in this regard.
5)What synchronizes the firing of the electron gun and the raster/deflection of the beam in order for the picture to be accurate? My own guess would be that there is a local oscillator in the tv set as well as a common oscillator at the transmitting facility so they synchronize the video signal to match the horizontal scan frequency (for PAL that being 15,625 kHz) so that whenever the video signal makes the gun fire the beam as a whole is in the correct position ?PS. what about the vertical frame rate is that synchronized to grid frequency and at which end, the transmission one or both? I see for PAL it's 50hz which are interlaced so a "real" frame is formed only at 25hz while for NTSC it is 60hz i so a real frame is 30 hz. Was this done deliberately to simplify broadcasting equipment?
thanks.
I actually have one older CRT set with an open back in another room so I went to check my "question" out a bit before asking.
1) Is it right that the video signal (after some input demodulation etc boards) directly then goes and controls the cathode ray electron gun?
2)Am I right in assuming that the deflection coils only move (raster) the electron beam across the screen to form horizontal lines/retrace as well as perform vertical retrace of the beam diagonally in order to start a new frame while the exact pattern in which the electrons from each of the 3 guns (color tv)or single gun(black&white) hit specific spots/pixels on the screen in each horizontal line is controlled by the video signal in the electron gun?
3) If I had a single white stripe vertically in the midst of my screen does that mean that in a single frame in each of the horizontal lines the electron gun would only fire at the moment which coincides with the time when the beam is at the mid position?
4) Would it be fair to say that the way in which a video signal controls the control grid of a CRT electron gun is very similar if not exact to the way an audio signal would control the grid of an audio amplifier vacuum tube ? in an audio tube there is considerable idle bias current to achieve linear operation and minimize crossover distortion, what happens within a CRT electron gun in this regard ? I would tend to think that the crt's electron gun is much more nonlinear in this regard.
5)What synchronizes the firing of the electron gun and the raster/deflection of the beam in order for the picture to be accurate? My own guess would be that there is a local oscillator in the tv set as well as a common oscillator at the transmitting facility so they synchronize the video signal to match the horizontal scan frequency (for PAL that being 15,625 kHz) so that whenever the video signal makes the gun fire the beam as a whole is in the correct position ?PS. what about the vertical frame rate is that synchronized to grid frequency and at which end, the transmission one or both? I see for PAL it's 50hz which are interlaced so a "real" frame is formed only at 25hz while for NTSC it is 60hz i so a real frame is 30 hz. Was this done deliberately to simplify broadcasting equipment?
thanks.
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