Bistatic Radar Detection Using Non-Cooperative FM Transmissions
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Solution Overview
Problem
Passive detection systems using non-cooperative FM radio transmissions face limitations in detection performance due to bandwidth limitations, resulting in limited distance resolution and dynamic range, which restricts the ability to accurately locate and distinguish targets from clutter.
Innovation Solution
A method that utilizes bistatic mode operations by receiving and filtering signals from multiple frequency channels, performing coherent integration, and ambiguity management to enhance signal-to-noise ratio and distance resolution, allowing for improved target detection and location accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-cooperative FM radio transmissions are used for passive detection, then the system can operate without active transmission, but the bandwidth limitation of individual FM channels restricts distance resolution to several hundred meters
Solution Approach 1:
The patent combines multiple FM radio channels (each with limited bandwidth) into a single detection system. By coherently integrating signals from multiple channels with different frequency bands, the system achieves an effective bandwidth equal to the sum of individual channel bandwidths, thereby improving distance resolution while maintaining passive operation
Solution Approach 2:
The patent transitions from single-channel detection to multi-channel detection by adding the frequency channel dimension. This allows the system to exploit the frequency diversity of multiple FM channels, effectively increasing the total bandwidth available for distance measurement without requiring higher bandwidth individual channels
2Device complexity
If single FM channel is used for detection, then the system complexity is reduced, but the dynamic range is limited to 40-50 decibels
Solution Approach 1:
The patent merges detection results from multiple FM channels through coherent integration. Each channel provides independent detection data, and their combination increases the dynamic range from 40-50 dB to over 60 dB, enabling detection of targets with widely varying radar cross sections while managing system complexity through standardized processing procedures
3Ease of operation
If the transmitting source position is known, then passive location is facilitated, but this limits the system to using civil transmission infrastructures with fixed installations
Solution Approach 1:
The patent creates a universal detection method that works with any FM radio transmission source regardless of whether its position is known or unknown. The system can detect and locate targets using reflections from any FM transmitter in the coverage area, making the detection system adaptable to various deployment scenarios without requiring pre-configured transmitter positions
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
The method increases the dynamic range and distance resolution of target detection, reduces ambiguity, and improves the signal-to-clutter ratio, enabling more accurate target location and detection, even in varying signal bandwidth conditions.
Implementation Method 1
receiving the signal transmitted by the non-cooperative source along a direct route
Implementation Method 2
reception of echoes reflected by elements located in the space covered by the transmitting source
Implementation Method 3
Estimation of bistatic distance and Doppler velocity by extracting the position of the detected peaks
Data Source
AI summary
The invention relates to the field of electromagnetic detection systems operating in bistatic mode, in particular to UHF/VHF bistatic radars. The method according to the invention consists in the simultaneous use of signals transmitted by one or more transmitting sources on separate frequency channels. The method includes a step of multichannel reception and separating channels. Additionally, the method includes a step of analysis of the signals received channel by channel, wherein the analysis is performed by correlation of the signals received with copies of the time and frequency shifted reference signals. The reference signals are constituted by the signals received from transmitting sources by direct transmission with a step of integration of the signals analysed, channel by channel, and a step of detection. The method according to the invention enables a signal to be used whose band-width is equal to the band covered by the set of channels used, which improves the contrast and distance resolution of the system implementing said method compared with the systems known from prior art.