Phase frequency detector-based high-precision feedback frequency measurement apparatus and method
摘要:
A phase frequency detector-based high-precision feedback frequency measurement apparatus and method: a Field Programmable Gate Array (FGPA) roughly measures a frequency fx of a measured time-frequency pulse by an equal-precision frequency measurement method; a Direct Digital Synthesizer (DDS) automatically synthesizes a frequency fx′ according to the fx roughly measured by the FPGA; the fx and the fx′ are sent to a phase frequency detector for performing phase frequency detection and then sent to the FPGA after passing through a charge pump, a low-pass filter circuit, and an (Analogue-to-Digital) A/D converter; the FPGA processes a frequency difference obtained by the phase frequency detector and then transmits the processed frequency difference to the DDS to form a negative feedback frequency measurement system so that the DDS continuously adjusts the fx′ according to a frequency difference measurement result until the output of the DDS is stable. Therefore, precise measurement of the time-frequency pulse to be measured is realized.
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