A broadcaster could also choose to use two modulation schemes; simultaneous use of TC8PSK and QPSK realizes a hierarchical transmission scheme that extends the broadcaster's service availability.

This demodulator is suitable for the quadrature phase-shift keying (QPSK) modulator previously published by the same author, "Novel Low-Cost QPSK Modulator Needs No Adjustments ...

The QPSK modulation provides double data rate than the BPSK modulation technique. The certain impairments associated with the FSO system are also studied in this paper.