“…For instance, when the standard frequency is close to the frequency to be measured or is a multiple of it, concentrated fuzzy areas are generated, and measurement results which are apparently higher than the circuit resolution by 2-3 orders of magnitude, are acquired. [11,12] There are a variety of frequency signals in frequency standard technology, telecommunication, exploration of natural phenomena, and electronic engineering, [13][14][15] such as the frequency signal of 1, 420, 405, 750 Hz of a hydrogen atom's energy-level transition, 19.59425 MHz in a hydrogen atomic clock, 9, 192, 631, 770 Hz of a cesium-atom energy-level transition, 16.384 MHz and 19.44 MHz in telecommunication, 4.43361875 MHz of the subcarrier in a color television, signals used in global positioning systems (GPS), etc. When only one standard frequency signal is utilized to measure any signal in a wide range of frequencies, the phase coincidence detection fuzzy areas are always discrete because of the complex relationship between them.…”