What pre war TV looked and sounded like

[wa2ise]

The prewar TV standard was pretty much the same as modern B&W NTSC, except it was 441i instead of 525i. Also the sound was AM, not FM. For a rough simulation of the picture, you could get a "widescreen" DVD movie, and feed the DVD player's luma output to a B&W TV set (via a TV modulator). Mask off with a paper cutout about 20% of the CRT (10% top, another 10% bottom, and also left and right). Or set the vertical and horizontal width 20% too big (I doubt you'd want to mess with these, thus the paper mask for this demo). Instead of 480 active video lines it would have been 404 lines. But the standard still called for 4.2MHz of horizontal resolution, so you would have seen more resolution left-right than up-down. Not a lot more, but some (about 20%). Like what you see with a direct baseband video connection from the DVD player.

To complete the similation, we have to make the sound sound like that from an AM signal 4.5Mhz above the picture carrier. A significant problem in TV set design is that, to make the sound come in despite tuner mistuning, intercarrier is used (pick off the 4.5MHz sound carrier off the video detector). Problem is that the sound carrier gets contaminated with buzzes and such from the video carrier and low frequency video content. FM is much more robust in rejecting this source of interference. To create this interference on a baseband audio signal (from the DVD player) that feeds an audio amp, mix in a small amount of the luma video signal. 30dB down would be about as much one could reasonably expect to achieve in a prewar TV set. You'd also hear (as well as see) car ignition and noisy brush motors.

If the TV set did not use the intercarrier system, you'd lose the sound very quickly if the tuner is mistuned. Ever play with an analog tuned SW radio on one of its highest SW bands, the one going from 12 to 30MHz. Breath on the tuning dial and you lose that SW station. It would be worse with a TV tuning from 45 to 100MHz (where the original TV channels were to reside). The sound would probably sound better with less interference from the video carrier.

As much as Sarnoff freaked, the FCC made a wise move to make the sound carrier FM. Maybe had Armstrong suggested to Sarnoff that FM sound for TV would have made TV even a better killer product, well....