Absolute phase modulation with holographic encoding

The widespread relative phase modulation method has disadvantages compared to absolute phase modulation: the need to transmit a pilot signal at the beginning of a communication session, lower noise immunity, and a more complex hardware implementation. In addition, with a random phase jump, not only the current symbol is distorted, but also the next one, and the correction of a double error requires the use of a correcting code with a higher correcting ability. However, absolute phase modulation, despite its advantages, is almost never used due to switching to the "reverse operation" mode when the phase of the reference signal jumps. A solution to the problem of using absolute modulation is provided by considering the phenomenon of "reverse operation" in terms of error-correcting coding, from the point of view of which "reverse operation" is a set of burst errors, the number of which can reach 100% of the length of the transmitted code word. For most error-correcting codes, correcting more than 50% of burst errors is an unsolvable problem, but the holographic position code gives the same decoding result for both the direct and the inverted data block. A soft decoder of a holographic code is described that ensures error-free decoding of a signal with absolute phase modulation without using a reference signal with phase jumps up to two times during the reception of one data block.