Multistatic Radar Target Location via Data Link Reference Signals
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Solution Overview
Problem
Current passive multistatic radar systems for air traffic surveillance face limitations due to the need for transmitters and receivers to be in line of sight, leading to restricted coverage, especially at high altitudes, and are unsuitable for civil air traffic monitoring due to signal attenuation and uncertainty in target location.
Innovation Solution
A method and system that utilize a data transmission link to receive reference signals from out-of-sight transmitters, allowing receivers to reconstruct direct propagation replicas and determine target position using correlation, enabling accurate location of targets beyond line-of-sight distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If passive multistatic radar systems use line-of-sight configuration, then signal reception is reliable, but coverage area is restricted especially at high altitudes
Solution Approach 1:
The patent introduces a data transmission link as an intermediary carrier to transport reference signals from transmitters to receivers. This mediator enables signal transmission between out-of-sight transmitter-receiver pairs, allowing receivers to obtain reference signals without direct line-of-sight connection, thereby extending coverage to high-altitude areas while maintaining signal reliability through the intermediary data link.
Solution Approach 2:
The patent transitions from a spatial line-of-sight constraint to a data link dimension for reference signal transmission. By separating the reference signal transmission path (via data link) from the radio signal propagation path (via reflection), the system adds a new dimensional channel for communication, enabling out-of-sight operation and expanding three-dimensional coverage volume.
2Measurement precision
If transmitters and receivers are placed close together for line-of-sight operation, then direct signal propagation is possible, but high-altitude surveillance is compromised due to blind cone
Solution Approach 1:
The data transmission link serves as an intermediary that decouples the geometric relationship between transmitters and receivers. By using this mediator to deliver reference signals, the system can place receivers far from transmitters without losing signal acquisition capability, thereby eliminating the blind cone effect and improving both coverage and location accuracy through proper signal reconstruction.
Solution Approach 2:
The system performs preliminary action by pre-transmitting reference signals through the data link to receivers before they are needed for target detection. This allows receivers to have reference signals ready in advance, enabling them to reconstruct direct propagation signals and accurately determine target positions even when physically distant from transmitters.
3Measurement precision
If television signals are used for passive detection, then bandwidth is sufficient for accuracy, but beam directionality limits transmitter-receiver distance
Solution Approach 1:
The data transmission link acts as an intermediary that compensates for the directional limitation of television beams. By transporting reference signals through this intermediary channel, the system can maintain the narrow beam characteristics of television signals for accurate target detection while simultaneously allowing receivers to be positioned at much greater distances from transmitters than the beam width would normally permit.
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 extends the coverage area by allowing receivers to be placed farther from transmitters, eliminating the 'blind cone' at high altitudes and improving the accuracy of target location, even at distances where signal attenuation is significant, thus enhancing air traffic surveillance capabilities.
Implementation Method 1
receiving, by means of N≥1 receivers, radio signals of opportunity emitted by M≥1 transmitters and reflected by said target
Implementation Method 2
Their relative propagation delay, Δt p =ΔL/c=(L 2 -L 1 )/c (c being the propagation speed of the radioelectric signals, i.e. the speed of light) can then be determined by cross-correlation
Implementation Method 3
In the case of a moving target, the reflected signal is shifted in frequency by Doppler effect
Data Source
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Figure 3A~3B
Figure 4~7
AI summary
A method for locating a target characterised in that it comprises the following steps: a) receiving, by means of N ≥1 receivers (RR1, RR2, RR3), opportunity radio signals (SRE) transmitted by M≥1 transmitters (ER) and reflected by said target (C), in which N×M≥3, said or at least one of said transmitters being located out of sight of said or at least one of said receivers; b) receiving, by means of a data transmission link (LD), one or a plurality of so-called reference signals, representative of the radio signals transmitted by said or each of said transmitters located out of sight of said or at least one of said receivers; and c) determining the position of said target from said radio signals and from said reference signal or signals. Application of such a method to the primary monitoring of air traffic. A multistatic radar system for implementing such a method. An air traffic monitoring system comprising, as primary radar, such a multistatic radar system.