Application of Microwave Doppler Sensor for Remote Vibration Measurement

This article describes a novel application of the microwave Doppler sensor as a remote vibrometer. The sensor is used to measure the speed of amoving object. Consider a situation where the Doppler sensor is fixed in place and the object is also fixed but vibrates, such as a factory motor. When the vibration amplitude is less than a quarter of the carrier wave of the sensor, it outputs the vibration amplitude under certain conditions. When the sensor attached to a mechanical oscillator with frequency f(s) and known amplitude delta(s) faces a target vibrating with frequency f(t) and amplitude delta(x), its output shows mixed frequency voltages. Assuming f(s)not equal f(t), the mixed frequency voltage can be resolved into components by using either filters or the fast Fourier transform (FFT) algorithm. As the voltages V-s and V are proportional to the known amplitude delta(s) and the vibration amplitude delta(x), respectively, the vibration amplitude can be calculated using delta(x) = (V/V-s)delta s, where V-s and V are the amplitudes of the voltages with frequencies f(s) and f(t), respectively. On conducting experiments by varying the distance between the sensor and an object vibrating at 18 Hz from 0.1 to 1 m, the average vibration amplitude was obtained to be 508 mu m with an error of 9 mu m.

Automated summary

This article describes a new application of the microwave Doppler sensor as a remote vibrometer. The sensor is used to measure the speed of a moving object. Experimental results show that the vibration amplitude of an object can be accurately calculated using filters or the fast Fourier transform algorithm.