Cross-talk and intermediate frequency deviation effects on phase-shift range finder

 In this paper, design and assembly of a new phase-shift range finder and also the cross-talk effect and the effect of intermediate frequency (IF) deviation on the range finder, is presented. Using the heterodyne technique, the system was able to measure very small phase-shifts, hence, considerably increasing the accuracy of the distance measurements. Since the major error in such systems is due to the phase measurement (counter-clock pulse), related to the cross-talk and the frequency shift, it was necessary to take especial steps to decrease these errors. Therefore, after testing the system, practically a simulation of the system was also carried out. Using the simulation results, the error due to the cross-talk was about 2% in the worst condition. The error related to the frequency changes was about zero, and the resolution due to the counter-clock pulse became 21 mm. Considering the signal to noise ratio of 20dB and the noise current of 42.8pA at the input current to voltage inverter, the lowest detectable optical power at the APD input, which the noise could be ignored, was 23 pW