New digital phase meter concept and its application

A new concept for digital phase meters, which in practical embodiment provides most of the commonly desired performance features such as wide bandwidth, high resolution, high speed measurement, etc., is presented. This meter emulates a Vernier caliper and inherits its characteristics. Phase difference may be measured in any period of the measured signals. In the basic theory, two phase-locked-loop circuits are used as frequency multipliers which divide each period of the input signals into multiple equal time slots, thereby emulating the divisions of space inscribed on the scales of a caliper. A simple ''pseudophase detector'' made of a D-type flip-flop is used to compare the location of the time slots on boil of the scales, just as we use the Vernier caliper. The new meter's resolution remains very high at both very high input frequencies and output data rates and while maintaining a wide input bandwidth; a resolution of 100 at 10 MHz input and 10 MHz output is easily attainable with off-the-shelf components requiring no clock rate higher than 100 MHz. In addition to a discussion of the theory, experimental results of a test embodiment are presented, Using a 10 MHz clock, a rather crude lest circuit could detect a delay rime of 400 ns between an original and delayed 40 kHz signal, equivalent to a resolution of similar to 65 000. (C) 1997 American Institute of Physics.