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How is the video signal on the discs modulated? Because I assume they would need to be modulated on a carrier since the tonearm itself would otherwise act like
by Tabular-Iceberg 5y ago
How is the video signal on the discs modulated? Because I assume they would need to be modulated on a carrier since the tonearm itself would otherwise act like a low pass filter.
Edit: meant high pass filter
- gugagore 5y agoI don't have a direct answer. I'm not sure how the signal is synchronized. But I will say that the tonearm of a record player exhibits the same behavior, yet the signal on a record is not modulated.
- Tabular-Iceberg 5y agoYes, but audio records don’t have to encode frequencies below the human hearing range, whereas a video one should be capable of showing multiple consecutive black or white frames. The pickup doesn’t detect groove depth, it detects change in groove depth. My guess is that they used AM since all you’d have to do was amplify it and send it straight to the lightbulb, no demodulation necessary.