Repository navigation
Differential encoding clarification. #117
Description
In the "Differential Encoding" section we have the following:
"When the receiver synchronizes to it, and aligns the BPSK to the “I” (real) axis, it has no way of knowing if it is 180 degrees out of phase or not, because the constellation is symmetric."
Does not knowing if it is 180 degrees out of phase or not is differentiating between the 0 (say 0 degree) and 1 signal (180 degree)? Also does aligning to the real axis mean trying to determine the phase angle w.r.t to the real axis (0 degree as reference) or just mapping directly on the real axis?
Activity
777arc commentedon Jan 5, 2026
Right, for example of the transmitter sent 001101 the receiver doesnt know whether the tx sent 001101 or 110010. "aligns the BPSK to the real axis" really just means rotating so that the clusters are on the real axis, as well as it can, so it does that by minimizing the imaginary part of the received symbols.