Ultrasonic Doppler Motion Sensor Phase Shift Feedback Reduction
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Solution Overview
Problem
Ultrasound Doppler motion sensor devices face issues with parasitic feedback, interference from adjacent sensors, and pressure fluctuations, leading to reduced detection quality and range.
Innovation Solution
Implementing a phase shift between the ultrasound transmission and reception signals, using a microcontroller to adjust the phase shift, and detuning the oscillator frequency to minimize interference, along with improving noise immunity by adjusting pulse width, effectively reducing feedback and ambient pressure noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If ultrasound transmission and reception means are placed in close spatial proximity for compact sensor housing, then device compactness is improved, but parasitic feedback from transmission to reception means increases causing detection failures
Solution Approach 1:
The patent changes the frequency parameter of the ultrasound transmission and reception means to different values. The transmission means operates at a first frequency while the reception means operates at a second frequency, preventing parasitic feedback by ensuring that the transmitted signal does not interfere with the received signal even when the means are in close proximity.
2Area of stationary object
If multiple ultrasound motion sensors are deployed in adjacent areas for comprehensive coverage, then detection space is improved, but mutual interference between adjacent sensors increases causing erroneous detections
Solution Approach 1:
The patent assigns different operating frequencies to adjacent sensor units. Each transmission means operates at a unique first frequency while its corresponding reception means operates at a matching second frequency. This frequency differentiation allows multiple sensors to operate simultaneously in adjacent areas without mutual interference, as each receiver only detects signals at its specific frequency.
3Ease of manufacture
If standard ultrasound Doppler technology is used for motion detection, then cost-effectiveness and ease of manufacture are improved, but sensitivity to pressure fluctuations and environmental disturbances increases
Solution Approach 1:
The patent uses different frequency parameters for transmission and reception means, creating a frequency-differentiated system that maintains the simplicity and cost-effectiveness of standard ultrasound Doppler technology while adding immunity to environmental disturbances through frequency selectivity.
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
Enhances detection quality and range by reducing parasitic feedback and ambient noise, improving sensitivity and reliability of motion detection.
Implementation Method 1
a continuous transmission signal having a typical carrier frequency of approx. 40 kHz radiated (emitted) by the transmitting means is reflected by an object moving in the detection space
Implementation Method 2
the reflected signal is received by the ultrasound reception means, after which mixer and detector means are used to determine a Doppler frequency that depends on a speed of motion of the detection object
Data Source
AI summary
An ultrasonic doppler motion sensor device includes a transmitter (10, 12) for emitting a continuous ultrasonic transmission signal in a detection space, an ultrasonic receiver (20, 22) for detecting the ultrasonic transmission signal reflected by the detection object as a receive signal, and a mixer and detector (14, 18) for mixing the ultrasonic transmission signal or a signal derived therefrom with the receive signal and/or for demodulating the receive signal and for generating a motion detection signal therefrom, wherein the mixer and detector are assigned a system (14) for the adjustable generation of a phase shift greater than 0° between a phase of the ultrasonic transmission signal and a periodic impulse signal at the mixer or detector for scanning and mixing the receive signal.