Frequency meter and method for measuring duty ratio and frequency

Abstract

The invention relates to a frequency meter. The frequency meter comprises a frequency measurement timing module, a serial-parallel conversion module, a counting module and a frequency measurement module; the frequency measurement timing module is connected with the counting module; the serial-parallel conversion module converts the serial data into parallel data and then sends the parallel data tothe counting module; the counting module counts the high level and low level of the parallel data and acquires the cycle amount of any data in the parallel data; the frequency measurement module is connected with the serial-parallel conversion module ad used for acquiring a low level value and a high level value of the parallel data. The frequency meter disclosed by the invention is simple and ingenious in design, and cannot occupy the additional hardware resource, thereby solving a condition of measuring a measured signal with higher frequency by a low-frequency system main clock by utilizing the high-speed IO in the low-cost FPGA.

Description

technical field [0001] The invention belongs to the field of measurement, and in particular relates to a frequency meter and a method for measuring duty ratio and frequency. Background technique [0002] At present, the function of the built-in frequency meter of the domestic direct digital frequency synthesizer DDS (Direct Digital Synthesizer) type signal source mainly includes two methods of measuring frequency and measuring period. Such as figure 1 Shown is a schematic diagram of the structure of the frequency meter used on the existing signal source, wherein the frequency measurement and timing module 101 uses the system clock to work, and the counter takes a constant 1 as a step; The number of periods of the signal under test is measured in the same counter with a constant 1 as the step; the low frequency measurement module 103 calculates the length of each period. [0003] The above measurements are all implemented by FPGA (Complex Programmable Logic Device), but the...

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Problems solved by technology

[0004] In view of the above problems, the object of the present invention is to provide a frequency meter and a method for measuring duty cycle and frequency, which solves the problems of low operating speed of ordinary frequency meters in the prior art and the need to manually set the duration of the measurement time gate

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