Polarisation-Switched Radar for Interleaved Short and Long Pulses
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Solution Overview
Problem
Current radar systems using temporal interleaving of short and long pulses face interference from echoes of short pulses during long pulse reception, leading to spurious signals and reduced compression gain, especially in distant areas.
Innovation Solution
The system employs two co-located radiating sources to emit short and long pulses with distinct polarizations, using phase shifts to differentiate between the pulses, allowing for simultaneous coverage of near and far areas without compromising detection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If temporal interleaving of short and long pulses is used to cover near and far areas, then radar coverage is improved, but interference from short pulse echoes during long pulse reception increases
Solution Approach 1:
The patent changes the polarization parameter of the electromagnetic waves to differentiate between short and long pulses. By assigning orthogonal polarizations (e.g., horizontal for short pulses, vertical for long pulses), the system allows simultaneous transmission and reception without interference, as the receiver can selectively process signals based on their polarization state.
2Object-generated harmful factors
If signal processing methods are used to eliminate nth-trace echoes, then interference is reduced, but system complexity increases
Solution Approach 1:
The patent extracts the harmful short pulse echoes from the reception signal by utilizing polarization filtering. Since the short pulses are transmitted with a different polarization than the long pulses, the receiver can selectively reject the short pulse echoes while preserving the long pulse echoes, eliminating the need for complex post-processing algorithms.
3Measurement precision
If ground reverberation echoes are received during far zone operation, then detection sensitivity is maintained, but compression gain is lost
Solution Approach 1:
The patent applies polarization discrimination to filter out ground reverberation echoes during far zone operation. By configuring the receiver to accept only signals with the polarization corresponding to long pulses, the system eliminates ground clutter while preserving the desired target echoes, thereby maintaining both detection sensitivity and compression gain.
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 effectively minimizes interference from short pulse echoes during long pulse reception, maintaining detection performance and reducing spurious signals, thereby enhancing radar range and coverage without losing compression gain.
Implementation Method 1
the short and long pulses being emitted as waves with distinct polarizations. The polarization of each emitted wave is obtained by simultaneously emitting, from two co-located radiating sources, for each pulse, two signals having a phase shift θ
Data Source
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AI summary
The invention relates to a method for transmitting/receiving radar and a device for implementing said method, the method alternately implementing two operating modes, a short-range mode using short pulses and a long-range mode using modulated long pulses, the method consisting, for each mode, in: - generating two synchronous radio frequency (RF) transmission signals having, between them, a phase shift θ of controllable predetermined value; - radiating two radio waves, each corresponding to one of the generated RF transmission signals, by means of two co-located radiating sources each having a predetermined polarisation axis; - receiving the backscattered radio signals picked up by each of the radiating sources and - outputting two radio frequency (RF) reception signals each corresponding to the radio signal picked up by one of the radiating sources, a phase shift θ' being applied between the two output signals, θ' being able to be determined as equal to θ.