A Technique of Ultra High Frequency Measurement

In the frequency comparison, two signals with multiple relations in frequency can be synchronal. This means that in a specific time interval, their phase will be periodically coincident. The general case is that, when minute frequency difference existing in the two signals with multiple relations in frequency, coincidence points of them will move forward or backward. The coincidence points can be strictly fixed in comparison between the two compared signals with exact integral multiple relations in frequency. The position change of this coincidence indicates the relative change of the phase difference of signals. With big frequency ratio condition, the ultra high frequency can be obtained from lower frequency signal that has the multiple relations with it and the relative change of their phase. An experiment demonstrating this technique was designed through phase processing method at GHz, in which the lower frequency signal was reshaped into a narrow pulse on a particular position of every period and be the sampling signal of the high frequency signal, and the high frequency was obtained indirectly through recording the position of the slowly moving coincidence points. With the improvement of frequency response of the coincidence measurement circuit, even higher frequency can be measured.