p/4 DQPSK (Digital Demod)

p/4 DQPSK (Differential Quadrature Phase-Shift Keying) is a differential format where the bits for a given symbol are determined by the phase change from the previous symbol. "p/4" adds an p/4 offset to the phase changes compared with the phase changes in plain DQPSK. This means there are a total of 8 ideal state positions (compared to the 4 for DQPSK). The ideal state positions for symbols alternate between the four 45-degree states normally used by QPSK and four on-axis states. Due to this alternation, the ideal trajectory between symbols never crosses through zero.

The following table shows the mapping of phase change to bit pattern:

Phase Change

Bit Pattern

p/4

00

3p/4

01

-p/4

10

-3p/4

11

See Also

DQPSK (Digital Demod)

QPSK (Digital Demod)

Setting up a Digital Demod Measurement

Available Digital Demodulation Formats

 

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