What is delay modulation in binary encoding?

Answer 1

In telecommunications, delay encoding is the encoding of binary data to form a two-level signal where (a) a "0" causes no change of signal level unless it is followed by another "0" in which case a transition to the other level takes place at the end of the first bit period; and (b) a "1" causes a transition from one level to the other in the middle of the bit period.

Delay encoding is used primarily for encoding radio signals because the frequency spectrum of the encoded signal contains less low-frequency energy than a conventional non-return-to-zero (NRZ) signal and less high-frequency energy than a biphase signal.

Delay encoding is an encoding using only half the bandwidth for biphase encoding but features all the advantages of biphase encoding: To be rewritten: It is guaranteed to have transitions every other bit, meaning that decoding systems can adjust their clock/DC threshold continuously. One drawback is human readability (e.g. on an oscilloscope)