Feedback Phase Demodulator for Low-Distortion CW Radar Signals
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Solution Overview
Problem
Traditional phase demodulators for CW Doppler radars face challenges in accurately demodulating phase signals due to high DC signal levels compared to AC signals, requiring high-performance ADCs with wide dynamic range, which is not always feasible.
Innovation Solution
A phase demodulator utilizing a negative feedback loop with a phase controller, phase shifter, mixer, and amplifier to control and amplify signals, allowing for phase lag or lead based on feedback signal magnitude and threshold, effectively reducing distortion and improving signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional mixer-based phase demodulation is used, then the phase demodulation structure is simple, but the DC signal level is 10 to 100 times greater than the AC signal level, requiring high-performance ADCs with wide dynamic range
Solution Approach 1:
The patent implements a negative feedback loop where the output of the mixer is fed back through an amplifier and phase shifter to the phase controller, which adjusts the phase of the reference signal. This feedback mechanism dynamically compensates for phase variations and reduces the DC signal level, allowing accurate demodulation without requiring high-performance ADCs with wide dynamic range.
Solution Approach 2:
The patent changes the phase parameter of the reference signal dynamically through the phase controller based on feedback from the mixer output. By adjusting the phase parameter in real-time, the system optimizes the demodulation process and reduces the DC component, thereby improving the effective dynamic range for AC signal detection without requiring high-performance ADCs.
2Manufacturing precision
If high-performance ADCs with wide dynamic range are used to handle the large DC signal level, then signal distortion is reduced, but device complexity and cost increase
Solution Approach 1:
The negative feedback loop continuously monitors the mixer output and adjusts the reference signal phase accordingly, reducing the DC signal level at the ADC input. This allows the use of lower-performance ADCs with limited dynamic range while maintaining high signal conversion accuracy, thereby reducing device complexity and cost.
Solution Approach 2:
The phase controller acts as an intermediary between the mixer output and the reference signal generator, mediating the phase adjustments to optimize the signal before it reaches the ADC. This intermediary component enables accurate signal conversion without requiring the ADC itself to have high performance and wide dynamic range.
3Measurement precision
If the phase controller adjusts phase based on feedback signal magnitude and threshold, then demodulation accuracy is improved, but processing complexity increases
Solution Approach 1:
The phase controller adjusts the phase parameter of the reference signal based on the magnitude of the feedback signal relative to a threshold value. This parameter adjustment strategy improves phase demodulation accuracy by dynamically optimizing the phase relationship between signals while using relatively simple control logic.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables reliable and accurate demodulation of phase signals with reduced distortion, improving the reliability and accuracy of target information, particularly in applications like heart rate and respiration measurement and human life detection.
Implementation Method 1
a phase shifter that delays a phase of the first phase signal to output a first delayed signal
Implementation Method 2
a mixer that outputs a first mixing signal based on the target signal and the first delay signal
Implementation Method 3
an amplifier that outputs a first feedback signal generated by amplifying the first mixing signal to the phase controller
Data Source
AI summary
Disclosed is a phase demodulator, which includes a transmitter that outputs a reference signal to a target, a receiver that receives a target signal generated in response to the reference signal from the target, and a demodulation processor that demodulates the target signal, and the demodulation processor includes a phase controller that outputs a first phase signal based on the reference signal, a phase shifter that delays a phase of the first phase signal to output a first delayed signal, a mixer that outputs a first mixing signal based on the target signal and the first delay signal, and an amplifier that outputs a first feedback signal generated by amplifying the first mixing signal to the phase controller.