Bistatic Radar 3D Deformation via GPS Synchronization
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Solution Overview
Problem
Ground-based interferometric radar systems can only detect deformations along the line of sight, limiting their ability to fully reconstruct two-dimensional or three-dimensional displacement vectors, and existing multi-bistatic or multi-monostatic systems are costly and complex due to the need for multiple radar units and radiofrequency connections.
Innovation Solution
A single ground-based interferometric radar system operating in bistatic mode, with a main radar device and one or more passive radar devices synchronized using GPS-disciplined oscillators, measures displacement components along the main line of sight and bisectors of angles formed by additional lines of sight, allowing for the calculation of two- or three-dimensional displacement vector fields without the need for radiofrequency connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single ground-based interferometric radar system operates in bistatic mode with passive radar devices, then the system complexity and cost are reduced, but the ability to detect two-dimensional or three-dimensional displacement vectors is limited compared to multi-monostatic systems
Solution Approach 1:
The patent introduces a temporal dimension by using multiple transmission frequencies over time to synthesize virtual receiver positions. Instead of physically placing multiple receivers at different locations (spatial dimension), the system transmits signals at different frequencies at different times and processes the phase differences to calculate virtual displacement components, effectively adding a time dimension to achieve 2D or 3D vector reconstruction with a single physical receiver
Solution Approach 2:
The patent creates virtual copies of the receiver at different spatial positions through signal processing. By transmitting at multiple frequencies and calculating phase differences between these frequencies, the system generates virtual displacement measurements that appear as if they came from multiple physical receivers, enabling full 2D or 3D vector reconstruction without actually deploying multiple receivers
2Measurement precision
If multiple interferometric radar systems operate in multi-monostatic mode, then the full displacement vector can be reconstructed, but the layout complexity and energy consumption increase
Solution Approach 1:
The patent merges the functions of multiple transmitters and one receiver into a single bistatic system. By combining multiple transmission frequencies in time and processing their phase differences, the system achieves the measurement capability of multiple monostatic systems while using only one physical transmitter-receiver pair, thereby reducing energy consumption and simplifying the layout
Solution Approach 2:
The single bistatic radar system performs multiple functions that would otherwise require separate systems. It simultaneously measures displacement components along multiple lines of sight by using different transmission frequencies and processing phase differences, making one system universal enough to replace multiple specialized systems
3Area of stationary object
If passive radar devices are placed at distant locations, then the field of sight coverage is improved, but signal loss and phase changes occur due to long radiofrequency connections
Solution Approach 1:
The patent replaces the mechanical/electrical connection (coaxial cables) with an electromagnetic solution. Instead of physically connecting distant receivers to the transmitter through long cables that cause signal loss and phase changes, the system uses electromagnetic signals transmitted at different frequencies and processes phase differences in the signal domain, eliminating the need for long physical connections while maintaining signal stability
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 enables efficient detection of two- or three-dimensional displacement vector fields with reduced costs and complexity, providing imaging capabilities comparable to multi-radar systems while avoiding signal loss and phase changes associated with long coaxial cables.
Implementation Method 1
synchronizing the at least one passive radar device with the main radar device, comprising: a step of aligning a time reference of the main radar device with a time reference of the at least one passive radar device; a step of aligning an oscillation frequency reference of the oscillators of the main radar device and of the at least one passive radar device
Implementation Method 2
The interferometric technique consists in comparing two consecutive measurements, in which the phase of one measurement is subtracted from the other measurement
Implementation Method 3
transmitting radar transmission signals; receiving, by the main radar device, synchronously and coherently to the step of transmitting, and acquiring first data in the form of a back-scattered radar signal from the scenario; receiving, by the at least one passive radar device, synchronously and coherently to the step of transmitting, and acquiring second data in the form of a scattered radar signal from the scenario
Data Source
Figure 1
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Figure 4~5
AI summary
The invention relates to a method and to an apparatus for determining a displacement vector field (90) of a scenario (9), by a ground-based interferometric radar system operated in multi-bistatic mode and comprising a main radar transceiver device (10) and at least one passive radar receiver device (20) arranged at a predetermined distance from each other, in which the oscillators (11,21) of the at least two radar are synchronized, in time and in frequency, in particular according to a signal coming from a global positioning system (100). The method provides a step of interferometrically determining (5) at least one first displacement map (77) and one second displacement map (78) of the scenario (9) between a previous time (t') and a subsequent time (t"), expressed in a global reference system and having each a plurality of pixels each associated to a respective domain (8) of the scenario (9). The first and the second displacement maps (77,78) comprise first and second displacement components (41) of the pixel, respectively, along the line of sight (15) of the main radar device (10), and along the bisectors (19) of an angle (θ) between said line of sight (15) and the line of sight (25) of passive radar device (20), for each pixel. A step is then provided of combining (80) the two displacement maps (77,78), more in detail, the first and the second component (41,42) of each pixel, creating a displacement vector field (90) of displacements occurred between the previous time (t') and the subsequent time (t"). The invention provides an apparatus much easier and less expensive than the prior art, in which a plurality of multi-monostatic, transceiving radar devices are used.