Radar Proximity Sensor Baseband Signal Segmentation
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Solution Overview
Problem
Radar-based proximity sensors have a dead zone in front of them, making it difficult to detect objects approaching within 30 cm, and are unable to detect static targets due to their modulation methods, which also require complex and costly hardware.
Innovation Solution
A radar-based proximity sensor design that separates baseband signals into AC and DC components, filters and amplifies the AC components for moving object detection, and uses offset compensation for the DC components to detect static objects, allowing for reliable detection of both static and dynamic objects, including those close to the sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If homodyne continuous-wave Doppler radar sensors are used for presence detection, then the sensor can detect moving objects, but static targets cannot be detected and the dead zone remains approximately 30 cm
Solution Approach 1:
The baseband signal is segmented into AC and DC components through separate signal paths. The AC component path (with high-pass filter) detects moving objects, while the DC component path (with offset compensation) detects static objects. This segmentation allows the sensor to overcome the dead zone limitation and detect both static and moving targets at close ranges.
Solution Approach 2:
The patent changes the signal processing parameters by introducing offset compensation for the DC component and high-pass filtering for the AC component. This parameter change enables the system to detect both static objects (through DC component with offset compensation) and moving objects (through AC component with high-pass filtering), eliminating the 30 cm dead zone.
2Reliability
If high-pass filtering is applied to eliminate parasitic coupling effects, then the bias effect is eliminated, but static targets become invisible and slow-moving targets are difficult to detect
Solution Approach 1:
The signal processing is segmented into two parallel paths: one with high-pass filtering for moving object detection and one with offset compensation for static object detection. This segmentation allows the system to maintain signal accuracy for moving objects while extending detection capability to static objects without being limited by the high-pass filter.
Solution Approach 2:
The patent creates a universal detection system that can detect both static and moving objects using the same radar sensor. By processing DC and AC components through different paths with different filtering strategies, the system achieves multi-functionality, making the sensor adaptable to various detection scenarios.
3Loss of information
If complex I/Q mixer demodulators are used to detect movement direction, then directional information is obtained, but hardware complexity and cost increase
Solution Approach 1:
The patent applies partial action by using simplified signal processing that focuses on detecting the presence and basic movement of objects rather than providing complete directional information. This partial approach reduces hardware complexity while still achieving the primary goal of proximity detection and basic motion sensing.
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
Enables the detection of objects as close as 1 cm and static objects, reducing hardware complexity and cost, while allowing for gesture recognition and precise movement angle determination, enhancing reliability and versatility in various applications.
Implementation Method 1
A radar-based proximity sensor with a transmitting antenna (TX) for sending an output signal and with at least one receiving antenna (RX) for receiving a reflected signal
Implementation Method 2
the received signal is demodulated into baseband signals (I, Q) by means of an I/Q demodulator
Implementation Method 3
the respective AC voltage component is filtered and optionally amplified by means of a high-pass filter
Implementation Method 4
the respective DC voltage component optionally undergoes offset compensation
Implementation Method 5
at least one AC voltage component is supplied to a Doppler evaluation to detect moving objects
Data Source
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AI summary
The invention relates to a radar-based proximity sensor (1, 100, 200, 301, 400, 410, 500) with a transmitting antenna for transmitting an output signal and with at least one first receiving antenna for receiving a first received signal (7), with a signal generator (2) for generating the output signal, wherein the output signal is demodulated into the baseband signals (I, Q) (5, 6) by means of an I/Q demodulator (4), wherein the baseband signals (I, Q) (5, 6) are each mixed with the first received signal (7) by means of a mixer (8, 9, 50, 51, 52), wherein the baseband signals (5, 6) are split into an AC voltage component and a DC voltage component, wherein the respective AC voltage component is filtered and optionally amplified by means of a high-pass filter (10, 11), and the respective DC voltage component is optionally Offset compensation (12, 13) is performed, whereby at least one AC voltage component is supplied to a Doppler evaluation (18),to detect moving objects (505) and at least one DC voltage component is supplied to a near-range presence detection device (19) to detect static objects (505).