Circuit system and control method for directly demodulating frequency modulated signal based on phase-locked loop

Abstract

The invention provides a circuit system and a control method for directly demodulating a frequency modulated signal based on a phase-locked loop, wherein the system comprises an amplification module for amplifying an input radio frequency signal; a phase discrimination / frequency discrimination module for acquiring a frequency difference and a phase difference between the local oscillator and the amplified radio frequency signal; a band limiting module connected with the phase detection / frequency discrimination module to limit the bandwidth according to the frequency difference and the phase difference and amplify the bandwidth; a controllable gain amplification module that adjusts the amplitude of the output signal of the band limiting module in a controllable manner; and a frequency-controllable frequency synthesizer module which is connected with the controllable gain amplification module and the phase discrimination / frequency discrimination module, and generates corresponding frequency change according to the frequency difference and phase difference signal after gain adjustment, so as to carry out frequency adjustment and tracking. The system has the advantages of simple structure, low power consumption and strong performance, which can also be used for carrier frequency tracking and carrier error cancellation on the basis of demodulation of conventional frequency shift keying.

Description

technical field [0001] The invention relates to the technical field of frequency demodulation, in particular to a circuit system and a control method for directly demodulating a frequency modulated signal based on a phase-locked loop. Background technique [0002] With the gradual development of wireless communication systems, traditional frequency modulation signals such as BFSK (Binary Frequency-Shift Keying, two-division frequency shift keying), MSK (Minimum-Shift Keying, minimum frequency shift keying), GFSK (Gaussfrequency Shift Keying) , Gaussian frequency shift keying), etc., it is difficult to bring significant performance improvement to the communication system. The most primitive BFSK communication method provides the simplest system structure, and the more complex MSK and GFSK provide better spectrum occupancy. However, as the new modulation method enters the bottleneck, the system structure is gradually solidified, and the system performance is difficult to impro...

AI Technical Summary

Problems solved by technology

The power consumption of the pre-amplification and down-conversion parts cannot be reduced due to the use of RF amplifier modules and local oscillators

The signal demodulation part usually requires a high-performance analog-to-digital converter or frequency demodulator to convert the signal into a binary level signal, and the power consumption is still high

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