Distance Measurement Using Frequency-Divided Phase Comparison
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for determining the distance to a target object using electromagnetic waves have limited accuracy and spatial resolution, making them unsuitable for close-range applications such as motor vehicle distance detection, as they can only determine distances within one wavelength of the incoming signal.
Innovation Solution
The method involves reducing the frequency of both the incoming and reference signals by a pre-determinable divider factor, which increases the wavelength and accuracy of distance determination, and further enhances this by amplifying the incoming signal and converting it to a digital format for simplified processing and error reduction, using a frequency divider and phase comparator to evaluate the phase difference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the frequency of the outgoing signal is increased to improve distance measurement precision, then the wavelength decreases and the maximum measurable distance range within one wavelength is reduced, but the position resolution for close-range detection is improved
Solution Approach 1:
The patent changes the frequency parameter of the outgoing signal to approximately 24 GHz, which corresponds to a wavelength of about 12.5 mm. This frequency selection optimizes the balance between position resolution and measurable distance range for close-range applications in motor vehicles.
2Length of stationary object
If a chirp signal with increasing frequency is used to extend the measurable distance range, then the range of detectable distances is improved, but the spatial resolution decreases to approximately 0.75 m
Solution Approach 1:
Instead of using a chirp signal with continuously increasing frequency, the patent employs a periodic sinusoidal signal at a fixed frequency of approximately 24 GHz. This periodic action maintains consistent wavelength and phase relationships, enabling high spatial resolution while still achieving extended measurement range through phase unwrapping techniques.
Solution Approach 2:
The patent introduces an intermediary processing step that measures phase differences at multiple distinct distances and uses these measurements to calculate intermediate distance values with higher precision. This intermediary approach bridges the gap between limited direct phase measurement range and the need for extended measurement capability.
3Device complexity
If conventional phase difference measurement methods are used to determine distance, then the device complexity is kept low, but the distance determination accuracy is limited to within one wavelength
Solution Approach 1:
The patent performs preliminary measurements at multiple known distinct distances before the actual distance determination. These preliminary measurements establish reference phase difference values that are used to calculate accurate intermediate distances during normal operation, thereby extending accuracy beyond the single-wavelength limitation without adding complex hardware.
Solution Approach 2:
The system uses feedback from multiple phase difference measurements taken at different known distances to continuously refine and update the distance calculation algorithm. This feedback mechanism enables the system to achieve high precision distance determination by comparing current phase measurements against the established reference measurements.
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
This approach significantly improves the accuracy and spatial resolution of distance determination, allowing for precise measurement of distances much smaller than one wavelength, making it suitable for applications like motor vehicle obstacle detection without increasing the complexity of the device.
Implementation Method 1
electromagnetic waves in the form of an outgoing signal are transmitted by a transmitter and at least one part of the outgoing signals is reflected on the target object and is received by a receiver as an incoming signal
Data Source
AI summary
An apparatus and a method for determining a distance (r) to a target object (200) proposes transmitting electromagnetic waves in the form of a transmission signal (120a) by a transmitter (111a), receiving at least one part of said transmission signal (120a) reflected by a the target object (200) in the form of a reception signal (120c, 120d) by receiving device (111b) and evaluating the reception signal (120c, 120d) according a reference signal (1230b) which has a known phase difference with respect to the transmission signal (120a) and a frequency equal to the frequency thereof. The reference (120) and reception (120c, 120d) signal frequencies are reduced in a frequency divider (113) with the same predefined divider factor (x) while preserving the existing phase difference between the reference signal (120b) and the reception (120c, 120d) signal in such a way that a reduced frequency reception signal (120b′) and a reduced frequency reception signal (120d) are obtained. The frequency difference between the reduced frequency reception signal (120b′) and reduced frequency reception signal (120d′) is evaluated in order to determine the distance (R).