| 摘要 |
A method and apparatus for bias point control of a Differential Quadrature Phase Shift Keying (DQPSK) demodulator are provided by the present invention. Said method comprises, in step 1: applying a first bias voltage to an I-path of a DQPSK demodulator, and applying a second bias voltage to a Q-path of the DQPSK demodulator, then applying identical pilot voltage signals to the I-path and the Q-path respectively (S202); in step 2: executing filtering processing on the I-path differential current signals of the DQPSK demodulator collected by a balance receiver, and determining the bias point real-time value ?I of the I-path, and also executing filtering processing on the Q-path differential current signals of the DQPSK demodulator collected by the balance receiver, and determining the bias point real-time value ?Q of the Q-path (S204); in step 3, performing feedback control on the first bias voltage according to the real-time value ?I, and also executing feedback control on the second bias voltage according to the real-time value ?Q, so that ?I reaches the expected bias point value of the I-path and ?Q reaches the expected bias point value of the Q-path (S206). The above steps 2 and 3 are repeated cyclically at preset regular intervals (S208), so that ?I remains consistently at the expected bias point value of the I-path and ?Q remains consistently at the expected bias point value of the Q-path. The technical solution of the present invention enables the bias point of the DQPSK demodulator to be locked at any expected bias point value, facilitates digitization, and is not easily influenced by the external environment. |
