Equivalent phase comparison frequency and its characteristics

Equivalent phase comparison frequency (EPCF) is an important parameter between two frequency signals, and it shows their phase correlation. It is much higher than anyone of the two frequencies, and its period is equal to the group phase shift corresponding two most adjacent phase coincidences between the signals. For example, to two frequency signals with several MHz frequency, their EPCF can be several GHz or higher. This concept is based on time or phase analysis and processing approaches, not those of frequency. With it to process time and frequency signals much higher phase processing resolution can be obtained. It is special effective for showing the phase correlation of signals that have different frequencies. The characteristics of phase changes between two different signals were usually showed by relative changes of periodic group phase generated by least common multiple period. EPCF is also the higher resolution reflection of the relative phase and frequency correlation between two signals. Thus, the concept based on EPCF can be used in measurement, processing, control of time and frequency signals, and develop a lot of new techniques and instruments.