Radar Correlation Suppression via Frequency Variation
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Solution Overview
Problem
Existing radar systems face challenges in achieving high-resolution target object detection when objects are stationary, as they require a large number of antenna elements and snapshots to suppress correlation between received waves, leading to increased system size and low direction detection resolution.
Innovation Solution
A target object detection apparatus that uses time-domain averaging of correlation matrices by varying the frequency of transmitted electromagnetic waves during successive transmit/receive operations, generating an average correlation matrix that effectively suppresses correlation between incident waves, allowing for high-resolution detection without increasing the number of antenna elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spatial averaging method using multiple sub-arrays is used to suppress correlation between incident waves, then correlation suppression is improved, but the number of antenna elements and device size increase substantially
Solution Approach 1:
The patent changes the frequency parameter of the transmitted electromagnetic waves across different transmit/receive operations. By varying the frequency, the phase relationships of reflected waves from stationary target objects change, which suppresses correlation when correlation matrices are averaged over time, eliminating the need for multiple sub-arrays
Solution Approach 2:
The patent employs periodic variation of the transmitted wave frequency across successive transmit/receive operations. This periodic frequency modulation creates time-varying phase relationships that, when averaged over multiple periods, suppress correlation between incident waves without requiring spatial separation of antenna elements
2Reliability
If a large number of snapshots are used in spatial averaging to attain sufficient correlation suppression, then correlation suppression is improved, but the number of antenna elements required increases
Solution Approach 1:
The patent varies the frequency parameter of transmitted waves across snapshots, creating temporal diversity that suppresses correlation. This allows sufficient correlation suppression to be achieved with fewer antenna elements by exploiting frequency-domain variations rather than relying solely on spatial sampling
3Device complexity
If conventional time-domain averaging of correlation matrices is used, then the number of antenna elements is reduced, but correlation suppression is insufficient when target objects are stationary
Solution Approach 1:
The patent introduces frequency variation as a parameter change across transmit/receive operations. This causes the phase relationships of reflected waves from stationary targets to vary over time, enabling effective correlation suppression through time-domain averaging while maintaining a reduced number of antenna elements
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 accurate detection of target object directions and velocities with high resolution, even when objects are stationary, without the need for additional antenna elements, by effectively suppressing correlation between incident waves through frequency variation during time-domain averaging.
Implementation Method 1
transmitting and receiving circuitry for repetitively executing transmit/receive operations of transmitting scanning electromagnetic waves and obtaining received signals based on reflected waves respectively reflected from the target object(s)
Implementation Method 2
a correlation matrix which expresses correlation between respective received signals of the antenna elements
Implementation Method 3
The phase relationship between a set of received incident waves having high correlation will differ in accordance with the physical positions at which the waves are received
Data Source
AI summary
A target object detection apparatus periodically executes a transmit/receive operation to transmit radar waves and obtain received signals from resultant incident reflected waves from respective target objects. An individual correlation matrix of received signal values is derived for each one of a fixed plurality of successive transmit/receive operations, with the transmission frequency being changed at successive operations. Individual correlation matrices derived from respective transmit/receive operations are time-averaged to obtain an average correlation matrix for use in obtaining target object information such as direction or velocity, with effects of correlation between respective incident waves being suppressed.