Dorothy on old RCA 'CED' disc

[old_tv_nut]

The CED format changed the color subcarrier to a lower frequency for better readout, but still mixed with the luminance. It required a comb filter in the player to remove the resulting very coarse dot pattern that otherwise would be visible. The result is that the output had reasonable horizontal resolution but poor diagonal resolution. RCA had some demo material of a car going over a suspension bridge, and you could see the vertical wires, but the diagonal wires tended to disappear.

The sensing of the disc capacitance depending on detuning a resonant circuit that carried a 915 Mhz oscillator signal. This was the same frequency as early microwave ovens, which could interfere with the CED player.