一种比相法瞬时测频接收机的工程实现

An Engineering Realization of an Instantaneous Frequency Measurement Receiver by the Phase Comparison Method

射频信号经限幅、放大、功分后输出两路信号,其中一路通过特定长度的射频线进行延迟,再经延迟信号与另一路信号同时送达鉴相器进行正交鉴相,并输出鉴相后的sin和cos两路模拟信号。这两路信号是输入信号相位的函数,与输入信号的频率相关,经A/D转换器转换为数字量送到FPGA,并由FPGA进行判断、计算和编码,同时输出对应的频率编码,以实现测频功能。

The RF signal is divided into two part signal via limiter, amplifier and splitter. The first part signal is delayed by a special length RF cable. The delayed part signal and another part signal are delivered to orthogonal phase discriminator together and generate sin, cos analog signals. The sin and cos analog signals are the function of input RF phase and frequency. The two analog signals are changed to digital by A/D converter and fed to FPGA The FPGA outputs frequency code by estimating, calculating and coding, thus realizing frequency measurement.