摘要
某低空遥测系统为提高抗地面多径干扰的能力,采用了直序扩频调制,需要使用四相调制(QPSK)发射机。该发射机与信号采集电路采用数字接口,通过采用差分正交调制提高了系统性能,降低了本振泄漏;通过采用射频放大芯片将信号放大到29 dBm。经测试功率输出端的信号调制矢量误差(EVM)为5%。该发射机已经参与遥测系统的试验,结果证明工作稳定。
To enhance the ability of resisting multipath interference from ground, DSSS is applied in some low altitude telemetry, in which a QPSK transmitter is needed. The transmitter adopts a digital interface for the connection with the signal acquisition circuit. The system ferformance is improved by differential quadrature modulation which decreases the local oscilla- tor leakage. The modulated signal is amplified to 29 dBm by RF amplification chip. EVM of signal at power output end is 5%. This transmitter has been used in the system experiment stably.
出处
《现代电子技术》
2010年第22期156-158,共3页
Modern Electronics Technique
