International TV Standards Conference 1949

[ppppenguin]

Another problem for PAL is that the decoder needs a very precise one line delay. Accurate and stable to a small fraction of a cycle of subcarrier. You can receive PAL without a delay line (PAL-S) but it can introduce visible "venetian blind" effects on less than perfect signals. The SECAM one line delay needed only about 50ns accuracy and stability. This could be done with a steel rod rather than a quartz block.