Digital FM Receiver Phase Tracking Without PLL or VCO
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Solution Overview
Problem
Existing digital frequency modulation receivers are affected by the threshold effect, leading to rapid deterioration of signal-to-noise ratio and high hardware costs due to the use of phase lock loops and voltage-controlled oscillators, which also consume significant power.
Innovation Solution
A digital frequency modulation receiver design that includes a phase capturer, an adder, a digital filter, and a phase estimator, which generates a frequency variation signal by calculating phase differences and updating phase values, thereby achieving a virtual phase lock loop and reducing the need for physical components like voltage-controlled oscillators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a phase lock loop and voltage controlled oscillator are installed in an FM demodulation receiver, then the ability against threshold effect is improved, but the hardware cost and power consumption increase
Solution Approach 1:
The patent replaces the traditional analog phase lock loop and voltage controlled oscillator with a digital signal processing approach. Specifically, it uses a digital down-converter that performs phase tracking and frequency demodulation through digital algorithms, eliminating the need for expensive analog components like PLLs and VCOs while maintaining the ability to handle threshold effects
Solution Approach 2:
The invention changes the operating parameters from analog domain to digital domain. By converting the phase lock loop operation into digital signal processing tasks, the system achieves the same functional goals (threshold effect resistance) with different implementation parameters that reduce hardware complexity and power consumption
2Reliability
If a phase lock loop and voltage controlled oscillator are installed in an FM demodulation receiver, then the ability against threshold effect is improved, but the power consumption increases
Solution Approach 1:
The patent substitutes power-hungry analog components (PLL and VCO) with digital signal processing circuits. The digital down-converter implementation requires significantly less power while achieving the same threshold effect resistance, directly addressing the power consumption issue
3Device complexity
If traditional FM demodulation is used without phase lock loop, then the hardware cost is reduced, but the threshold effect causes rapid deterioration of signal to noise ratio
Solution Approach 1:
The patent implements a digital down-converter that performs phase tracking using digital algorithms instead of analog PLL. This digital approach maintains the signal-to-noise ratio performance by properly tracking phase variations, while avoiding the need for expensive analog components
Solution Approach 2:
The digital down-converter employs feedback mechanisms through digital signal processing to track phase and frequency variations. This feedback loop operates in the digital domain, maintaining reliability against threshold effects without requiring analog PLL components
Data Source
AI summary
A digital frequency modulation receiver includes a phase capturer, an adder, a digital filter and a phase estimator. The phase estimator is used to generate a first phase value according to an input signal. The adder is coupled to the phase estimator for subtracting a second phase value from the first phase value to generate a phase difference. The digital filter is coupled to the adder for performing a filtering calculation with the phase difference so as to generate a frequency variation signal. The phase estimator is coupled to the digital filter and the adder so as to update the second phase value according to the frequency variation signal.