Detecting moving radar target from fixed echoes - utilising variable frequency coherent oscillator frequency controlled from auto-oscillator

摘要

The coherent radar permits detection of moving target from amongst fixed objects utilising Doppler effects. The coherent oscillator is controlled from auto oscillator to vary intermediate frequency (IF) to provide frequency and phase control. The auto oscillator output is mixed with output from stabilised local oscillator to provide IF signal. This is applied to a variable frequency coherent oscillator to produce an output for phase demodulation of the IF signal. A second phase demodulator provides quadrature phase signal and both signals are used to derive frequency control signal for coherent oscillator and applied via varactor diode.