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## BER Performance of DQPSK

#### The bit error rate performance for DQPSK as a function of Eb/N0 can be seen to be significantly inferior to that for binary DPSK, and unfortunately does not share the unique property of coherent QPSK in giving no performance penalty for the gain in bandwidth efficiency. This is largely owing to the noise accompanying the delayed demodulator reference mixing with the orthogonal symbols and causing crosstalk in the demodulator. As a result, there is less motivation for the designer to use DQPSK as the effort needed to implement the carrier recovery for coherent detection will yield an approximate 3 dB improvement in performance. |