Patent ID: 11965919
Assignee: ZHEJIANG UNIVERSITY
Field: Measurement (Instruments)
Classification: CPC G  H | IPC G

Claim 0:
1. A phase frequency detector-based high-precision feedback frequency measurement apparatus, comprising a reference signal module (1), a frequency doubling module (2), a Field Programmable Gate Array (FPGA) (3), a Direct Digital Synthesizer (DDS) (4), a phase frequency detector (5), and a measured time-frequency signal (9), wherein
the reference signal module (1) generates a reference signal which is divided into two paths; one path of signal is connected to the FPGA (3) and serves as a clock source for the operation of the FPGA (3); the other path of signal is connected to the frequency doubling module (2); the signal of the reference signal module (1) serves as a clock source Fclk for the operation of the DDS (4) after being subjected to frequency doubling;
the measured time-frequency signal (9) is divided into two paths of signals; one path of signal serves as the initial measured frequency of the FPGA (3), and the other path of signal is connected to the phase frequency detector (5), and performs phase frequency detection with the frequency signal directly synthesized by the DDS (4);
the DDS (4) adjusts the output frequency under the control of the FPGA (3); first, the FPGA (3) roughly measures to obtain a measured signal fx; the DDS (4) synthesizes a reference signal fx′ close to the measured signal fx through a frequency control word M according to a roughly measured result thereof; and after the phase frequency detector (5) is enabled, the DDS (4) continuously adjusts the output frequency of the DDS (4) until reaching a stable state according to a difference value obtained by performing phase frequency detection on the measured signal fx and the signal fx′ synthesized by the DDS (4) under the control of the FPGA (3), and the measurement result at this moment is output by the FPGA (3).