HIGH ACCURACY MEASURING METHOD OF INTEGER MULTIPLE FREQUENCY OF 1KHZ

摘要

PURPOSE:To measure frequency in a short time with high accuracy, by converting a frequency to be measured, to a constant frequency synchronizing with the frequency to be measured, by use of a phase synchronizing oscillator, and after that, measuring an error frequency against an output of a standard oscillator. CONSTITUTION:A frequency to be measured is inputted to a phase comparator 9 through a 1/n variable frequency divider 10 and a 1/2 frequency divider 11, and an output of a voltage control type crystal oscillator 5 is phase-compared with an output divided by a 1/10010 frequency divider 6 and a 1/2 frequency divider 7. Error voltage corresponding to this phase difference is fed back to the oscillator 5 through a low-pass filter 8, and the oscillator 5 is phase-synchronized with the frequency to be measured. On the other hand, an output of the oscillator 5 is inputted to a mixer 2 together with an output obtained by multiplying a standard frequency from a standard oscillator, by a multiplier 1, and a difference frequency fetched through a low-pass filter 3 is measured by a frequency counter. In this way, a frequency of integer multiple of 1KHz can be measured with high accuracy in a short time, by a simple circuit.