Patent ID: 7106804

Claim:
A Pi/4 differential quadrature phase shift keying (DQPSK) modem, the modem comprising: a processing unit; and a storage device coupled to the processing unit and having stored there information for configuring the processing unit to: obtain Pi/4 differential quadrature phase shift keying (DQPSK) symbols; translate the Pi/4 DQPSK symbols into quadrature phase shift keying (QPSK) symbols utilizing the formula S QPSK ( t )=( real ( S ( t ))+ imag ( S ( t ))*( real ( S ( t− 1))− imag ( S ( t− 1))), where S(t) is a DQPSK symbol at time t, and S QPSK (t) is a QPSK symbol at time t; map the QPSK symbols to a pair of bits; obtain communication bits indicative of the outbound communication signal; translate the communication bits to three communication bits; and map the translated bits to DQPSK symbols.