Dual-Chirp Radar Measurement With Configurable Delay for High SNR
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Solution Overview
Problem
Conventional FMCW radar systems face challenges in achieving low energy consumption, high signal-to-noise ratio (SNR), and high spatial resolution due to limitations in chirp duration, frequency multiplication, and signal attenuation, which affect distance measurement accuracy and detection capabilities, especially in short-range applications like vital sign monitoring.
Innovation Solution
A radar measuring device that generates and uses two distinct radar signals with a configurable delay, allowing for low duty-cycle operation and avoiding time windowing effects, while maintaining high SNR and spatial resolution, by employing dual modulators and mixers to process signals with controlled initial phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the chirp duration is reduced to achieve low energy consumption and low duty-cycle operation, then energy consumption is reduced, but time windowing effects occur and SNR deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-generating a second reference chirp signal that is stored in memory with advance preparation. This allows the system to use short transmit chirps for low energy consumption while having a ready-made reference signal for mixing, eliminating the need for long continuous reference signals and avoiding time windowing effects that would degrade SNR.
Solution Approach 2:
The patent segments the reference signal generation into two distinct parts: a first reference chirp generated in real-time and a second reference chirp pre-generated and stored in memory. This segmentation allows the system to use short transmit pulses while maintaining high SNR through proper mixing with the pre-prepared reference signal, resolving the contradiction between low energy consumption and high reliability.
2Measurement precision
If frequency multiplication is used to achieve high carrier frequency for short-range applications, then spatial resolution is improved, but phase noise increases and SNR deteriorates
Solution Approach 1:
The patent uses copying by generating a reference chirp signal that is an exact copy of the transmitted chirp signal through memory storage. This copied reference signal maintains perfect phase coherence without the phase noise accumulation that would occur through additional frequency multiplication stages, thereby preserving SNR while achieving high spatial resolution through the original frequency multiplication process.
Solution Approach 2:
The patent introduces a memory storage unit as an intermediary between the chirp generator and the mixer. This intermediary stores the reference chirp signal in its ideal form without phase degradation, allowing the system to mix the received echo with a clean reference signal, thus maintaining high SNR despite the frequency multiplication used to achieve high carrier frequency for improved spatial resolution.
3Measurement precision
If the frequency band B is increased to achieve high spatial resolution, then spatial resolution is improved, but the required sampling rate increases and energy consumption increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the reference chirp signal that corresponds to the desired wide frequency band B in memory. This allows the system to use short transmit pulses with low sampling rates for energy efficiency, while the pre-stored reference signal enables proper mixing and processing to achieve high spatial resolution without requiring continuous high-rate sampling during transmission.
Solution Approach 2:
The patent uses periodic action by generating periodic chirp signals with duty cycle less than 100%, where the transmit chirp is short and periodic, and the reference chirp is periodically refreshed from memory. This periodic operation allows the system to achieve high spatial resolution through wide frequency band chirps while reducing energy consumption through low duty-cycle operation and low sampling rates during the off periods.
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 device achieves low energy consumption, high SNR, and high spatial resolution, enabling effective detection and tracking of vital signs with improved accuracy and reduced signal attenuation, particularly suitable for short-range applications.
Implementation Method 1
one mixer having a first input coupled to the receive antenna, a second input coupled to an output of the second generator
Data Source
AI summary
Radar measuring device including:a first generator of a first periodic radar signal whose frequency varies linearly, over at least one portion Tramp of a period Tin, in a frequency band B;a transmit antenna coupled to an output of the first generator and configured to transmit the first radar signal;a second generator of a second periodic radar signal whose frequency varies linearly, over said portion Tramp of the period Tin, in the frequency band B, which is generated with the same start-up phase as the first radar signal and having, relative to the first radar signal, a configurable delay τmix;a receive antenna configured to receive at least one echo of the first radar signal;a mixer comprising a first input coupled to the receive antenna and a second input coupled to an output of the second generator.