Frequency measuring method and apparatus

摘要

The frequency of a pulse signal is measured with the aid of a reference signal generated in an oscillator (11). Both the pulses of the frequency to be measured and the pulses of the reference frequency are counted by separate counters (12, 13) and the counts or counted results are stored in separate memories (14, 15). A flip-flop (21) is set and reset to determine each measuring duration. The difference between two successive counts of the measured frequency counter (14) corresponds to the pulses or rather periods counted during the measuring time duration. The difference between two successive counts of the reference frequency counter (15) corresponds to the length of the measuring time duration whereby the resolution is determined by the reference frequency. A microprocessor (16) divides the number of periods counted by the measuring time duration to ascertain the frequency to be measured which may then be displayed.