Multi-Aperture SAR Variable Pulse Repetition Rate Blind Area Elimination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current synthetic aperture radar (SAR) systems with multiple apertures cannot operate with a variable pulse repetition rate, leading to blind areas and non-uniform sampling, which hinders high-resolution wide-swath imaging.
Innovation Solution
A multi-aperture SAR method and device that employs a combined transmission and reception system with variable pulse repetition rates, converting first sampled values into second sampled values with optimized uniform spatial distance and phase centers, enabling digital beam shaping over multiple reception channels and radar echoes to suppress blind areas and ensure high resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single-aperture SAR system operates with a constant pulse repetition rate, then the system structure is simple, but the width of the detectable strip is limited due to blind areas
Solution Approach 1:
The patent applies dynamics by varying the pulse repetition rate in a multi-aperture SAR system. Instead of using a constant pulse repetition rate, the system dynamically adjusts the pulse repetition rate for different reception channels, allowing the radar to cover a wider strip without blind areas while maintaining system reliability.
Solution Approach 2:
The patent segments the single aperture into multiple apertures (reception channels) with different pulse repetition rates. This segmentation allows each channel to cover different range cells, eliminating blind areas and increasing the total detectable strip width by combining the coverage of multiple channels.
2Area of stationary object
If the pulse repetition interval is lengthened to increase the detectable strip width, then the strip width increases, but the azimuth resolution deteriorates
Solution Approach 1:
The patent divides the detection task across multiple reception channels, each with its own pulse repetition rate. This allows the system to maintain short pulse repetition intervals (high PRF) for azimuth resolution while collectively covering a wider strip through the combined effort of multiple channels with different PRF settings.
Solution Approach 2:
The patent changes the pulse repetition rate parameter for different reception channels instead of uniformly increasing it for all channels. This selective parameter change allows the system to optimize both strip width and azimuth resolution by assigning appropriate PRF values to different channels based on their specific detection requirements.
3Reliability
If a multi-aperture SAR system uses a constant pulse repetition rate, then the system structure is manageable, but continuous blind areas occur that block radar echoes
Solution Approach 1:
The patent implements dynamic pulse repetition rate variation across multiple reception channels. Each channel operates with a different PRF, and the system dynamically combines signals from these channels to eliminate continuous blind areas, achieving continuous coverage without excessive system complexity through coordinated PRF management.
4Reliability
If a single-aperture SAR system varies the pulse repetition rate to avoid blind areas, then blind areas are reduced, but the sampling becomes non-uniform requiring interpolation
Solution Approach 1:
The patent segments the sampling task across multiple reception channels, each performing uniform sampling at its own pulse repetition rate. This segmentation allows the system to achieve both blind area coverage and uniform sampling simultaneously, as each channel independently samples uniformly within its assigned range cells, eliminating the need for complex interpolation procedures.
5Measurement precision
If interpolation techniques are used to convert non-uniform samples to uniform samples, then uniform sampling is achieved, but the method cannot be transferred to multi-aperture systems
Solution Approach 1:
The patent inverts the conventional approach by not trying to convert non-uniform samples to uniform samples through interpolation. Instead, it directly generates uniform samples in multi-aperture systems by having each reception channel sample uniformly at its own pulse repetition rate, making the method naturally applicable to multi-aperture configurations without requiring interpolation techniques.
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 achieves uniform sampling in the azimuth direction, allowing for further processing of SAR data in the frequency domain, effectively eliminating blind areas and maintaining high resolution, thereby covering a wide swath of the earth's surface with improved signal quality.
Implementation Method 1
detecting radar pulses reflected from the earth's surface, which are emitted by a radar system
Implementation Method 2
radar pulses reflected from the earth's surface
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a synthetic aperture radar method for remote sensing of the Earth's surface (GR) using a multi-aperture radar system on a platform moving in an azimuth direction (x) above the Earth's surface (GR). The multi-aperture radar system comprises a combined transmitting and receiving unit (1), which, in transmitting mode, is a transmitter that emits radar pulses (RP), and, in receiving mode, is a receiver that receives radar echoes (EC) of these radar pulses (RP) reflected from the Earth's surface (GR) via several receiving channels (RC1, RC2, RC3, RC4). The transmitter emits radar pulses (RP) with a variable pulse repetition rate at successive transmission times.Furthermore, the radar echoes of the radar pulses (RP) are received by the receiving device via the respective receiving channels (RC1, RC2, RC3, RC4), thereby obtaining first samples (a1), each corresponding to a receiving channel (RC1, RC2, RC3, RC4) for a received radar echo (EC). In the method according to the invention, the first samples (a1) are converted into second samples by determining a respective second sample (a2) from the first samples (a1) in a receiving sequence (RS) of several radar echoes (EC) received successively by the receiving device, such that the antenna patterns of all receiving channels (RC1, RC2, RC3, RC4) for all radar echoes (EC) of the receiving sequence (RS) are weighted and combined based on one or more optimization targets. The optimization target or one of the optimization targets is a predetermined uniform spatial distance between the phase centers (PC') of the second samples (a2).