  In this paper, we address the problem of the decoding of variable length
physical layer header (PLH) codes. We take as a case study the DVB-S2X
standard, and, after selecting a suitable PLH code with variable codeword
length, we propose two alternative noncoherent decoding strategies. The
proposed decoding strategies allow to estimate the length of the transmitted
PLH field, which is unknown at the receiver, jointly with the decoding of the
PLH code. We demonstrate that it is possible to achieve an excellent decoding
performance while significantly reducing the overhead due to the transmission
of the PLH field with respect to a standard fixed-length PLH.
