[cctalk] Re: interlace [was: NTSC TV demodulator ]

CAREY SCHUG wrote: I've seen this lots - I'm not sure its entirely "interlace" - I tended to think more of the fact that CRT's scan causing the "pixel dots" to flash at high speed (not detectable to the human eye, but detecting a such a frequency is definitely possible for a bit of electronics. (Of course scan/interlace all contribute to the rate of picture elements flashing - all depends on what the particular device looked for) For example, I had an NES with the "light gun" - this was a gun you could use to shoot things moving around on the screen. When you pulled the trigger - the whole screen would flash - basically they quickly blanked it with only a small while square a the location of the moving item - during this time, they would look for a light image received by the (fairly highly focused) gun at the refresh frequency - so you couldn't just point it at a light source - it had to be the TV screen (or course you COULD fool it with another source "blinking" at the right frequency - but this was beyond the knowledge/ability of most who used the system :-) On an LCD TV - the gun didn't shoot! - LCD pixels tended not to be scanned/refreshed the same way, and are also slower - so whatever scan frequency might have been used isn't detectable. Dave ::: https://dunfield.themindfactory.com ::: "Daves Old Computers"->Personal