A multiple phase demodulation method for high resolution of the laser range finder

To have higher resolution of distance in the laser range finder using the phase demodulation method, signal should be modulated with a high frequency. In the signal processing of modulation and demodulation, it is inevitable to amplify the signals. However, it is not easy to amplify the high frequency since the amplifying gain is restricted by the frequency bandwidth. It is advantageous to demodulate using an intermediate frequency in which high gain amplification as well as less contaminated signal are obtained. Analytical and experimental results are presented to show how the intermediate frequency demodulation method works and how good performance are obtained in the time and frequency domains.