The doppler signal that is mixed and exported by microwaveinterferometer is a non-stationary signal, its instantaneous frequency is changing time variant.
微波干涉仪混频输出的多普勒信号是一个非平稳信号，其瞬时频率随着时间的变化而变化。
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A 3 cm X-band microwaveinterferometer with a phase-locked amplifier as detector has been used to measure small phase changes as a microwave beam passing through the gas discharge tube.