分析相位载波(PGC)解调中载波相位延迟产生的影响,表明载波相位延迟引起解调输出幅值衰减,严重时导致解调输出恒为零。提出采用载波相位超前技术消除其不利影响。在全数字PGC解调系统中,采用余弦查找表(LUT)方式生成载波数字波形,通过在LUT的地址输入端引入固定偏置,生成相位超前的载波,补偿解调系统中固有的延迟,达到消除不利影响的目的。固定偏置可以通过对解调系统进行分析和测试获得。实验结果表明,载波相位超前技术是有效的。

Carrier phase delay resulted in output signal fading in the Phase Generated Carrier (PGC) demodulation, and in critical conditions, the output signal vanished. A carrier phase advance technique was developed to solve this problem. The digital carrier waveform was generated using cosine waveform Look-up-table (LUT) in the digital PGC demodulation system. An address offset was introduced at the LUT input port and a phase-advanced carrier was generated. The phase advance completely compensated the constant delay in the demodulation system. The address offset could be obtained from both analysis and measurement of the demodulation system. Experiment result verifies that the carrier phase advance technique is effective.