Directional Microwave Sensor for Short-Range TOF Detection
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Solution Overview
Problem
Current time-of-flight ranging technologies face challenges in accurately detecting and measuring objects at short distances due to the need for extremely short transmit pulses and the difficulty in separating transmit and receive windows, which is not feasible with existing regulatory frequency limits and power constraints, especially in outdoor environments for applications like parking and traffic monitoring.
Innovation Solution
A directional speed and distance measurement sensor using a time-of-flight ranging technique with a battery-operated device that employs a transmit pulse train with a brief carrier wave burst of 1-3 nanoseconds, combined with adjustable receive window timing and high pulse repetition frequency, to enhance signal-to-noise ratio and comply with low power emission regulations, allowing for precise detection and measurement of objects in defined zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a time-of-flight ranging sensor uses a transmit pulse width of 1-3 nanoseconds to detect objects at short distances, then the separation between transmit and receive windows becomes adequate, but the emitted spectrum becomes very broad up to or above 1 GHz which exceeds regulatory frequency limits
Solution Approach 1:
The patent changes the temporal parameter of the transmit pulse from extremely short (1-3 nanoseconds) to longer duration (microseconds range), which simultaneously narrows the spectral bandwidth to comply with regulatory limits while maintaining adequate separation between transmit and receive windows through synchronized gating
2Object-generated harmful factors
If a time-of-flight sensor uses a transmit pulse width of microseconds range, then the emitted spectrum remains within regulatory limits, but there is no separation between the transmit pulse and receive pulse for short distance detection
Solution Approach 1:
The patent implements preliminary action by synchronizing the receive window to open immediately after the transmit pulse ends, creating a gated detection mode that provides adequate separation between transmit and receive operations even when using longer pulse widths that comply with spectral regulations
Solution Approach 2:
The patent employs periodic pulsed operation with alternating transmit and receive phases, where the sensor periodically switches between transmitting electromagnetic energy and detecting reflected signals, allowing adequate temporal separation while maintaining continuous monitoring capability
3Reliability
If a time-of-flight sensor uses high power transmission to improve signal-to-noise ratio, then detection reliability improves, but power consumption increases and battery life decreases
Solution Approach 1:
The patent uses periodic pulsed transmission rather than continuous high-power transmission, where the sensor transmits electromagnetic energy in brief pulses and remains in low-power receive mode during intervals, significantly reducing average power consumption while maintaining detection reliability through high peak power during transmission phases
Solution Approach 2:
The patent implements self-service through signal integration and averaging techniques where the sensor accumulates multiple reflected signal samples over time to improve signal-to-noise ratio, allowing the use of lower transmission power while maintaining detection reliability through post-processing of accumulated signals
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 reliable detection and measurement of objects such as automobiles in short distances with low power consumption, reducing interference and extending battery life, while maintaining compliance with regulatory frequency limits, thereby improving the accuracy and efficiency of applications like parking and traffic monitoring.
Implementation Method 1
directional speed and distance measurement sensor based on a time of flight ranging technique
Implementation Method 2
transmitting a microwave transmit pulse... radiating the transmitted pulse by a directional antenna system... receiving received pulses
Data Source
AI summary
A method of using a directional sensor for the purposes of detecting the presence of a vehicle or an object within a zone of interest on a roadway or in a parking space. The method comprises the following steps: transmitting a microwave transmit pulse of less than 5 feet; radiating the transmitted pulse by a directional antenna system; receiving received pulses by an adjustable receive window; integrating or combining signals from multiple received pulses; amplifying and filtering the integrated receive signal; digitizing the combined signal; comparing the digitized signal to at least one preset or dynamically computed threshold values to determine the presence or absence of an object in the field of view of the sensor; and providing at least one pulse generator with rise and fall times of less than 3 ns each and capable of generating pulses less than 10 ns in duration.