Bistatic SAR Phase-Preserving Modulation for Oscillator Error Compensation
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Solution Overview
Problem
Bistatic and multistatic synthetic aperture radar systems face issues with frequency and phase errors due to the use of different oscillators for transmission and reception, leading to increased complexity and costs, as well as the need for additional hardware for synchronization and large data memory requirements in receivers.
Innovation Solution
The method involves phase-preserving modulation of radar echoes by receivers, which are then transmitted to a signal processing platform for demodulation and frequency conversion using the same oscillator, eliminating the need for synchronization data transmission and reducing hardware complexity by avoiding frequency and phase errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different oscillators are used for transmission and reception in bistatic/multistatic SAR systems, then independent reception is achieved, but frequency and phase errors occur
Solution Approach 1:
A synchronization unit is introduced as an intermediary component that receives synchronization information from the transmitter and distributes it to all receiver units. This mediator ensures that all oscillators across the distributed system remain synchronized, eliminating frequency and phase errors while preserving the independent reception capability of the bistatic/multistatic configuration.
2Measurement precision
If synchronization information is transmitted between transmitter and receivers, then frequency and phase errors are compensated, but additional hardware and complexity are required
Solution Approach 1:
The synchronization unit performs multiple functions: it receives synchronization information from the transmitter, processes this information, and distributes it to all receiver units. This multi-functional component consolidates what would otherwise require separate synchronization hardware at each receiver, reducing overall system complexity while maintaining phase error compensation capability.
3Quantity of substance
If receivers have large data memory and powerful transmission devices, then SAR raw data can be stored and transmitted, but receiver complexity and costs increase
Solution Approach 1:
The patent merges the signal processing functions across the transmitter and receiver units. By processing received signals at the transmitter using synchronization information, the system reduces the burden on individual receivers, allowing them to use smaller memory and less powerful transmission devices while still achieving complete SAR data acquisition.
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 simplifies the SAR system by eliminating the need for synchronization data transmission and reduces hardware complexity and costs, while maintaining data quality by ensuring phase preservation during signal transmission.
Implementation Method 1
detecting radar pulses reflected on the earth's surface, which are emitted by a radar transmitter
Implementation Method 2
the signals to be transmitted are converted from a base frequency band into a predetermined frequency band in which the SAR system operates using a local oscillator
Implementation Method 3
the signals based on the received radar echoes are converted back into the base frequency band in the respective receivers
Data Source
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AI summary
The invention relates to a synthetic aperture radar method for remote sensing of the Earth's surface with one or more transmitters (Tx) and receivers on different platforms. Each transmitter (Tx) and each receiver (Rxl, Rx2, Rx3), as well as a signal processing platform (SP) above the Earth's surface, perform the following steps a) to c). In step a), the respective transmitter (Tx) generates signals (SI) in a base frequency band (BB) and performs a first frequency conversion (CON1) of these signals (SI) into a first frequency band (FB1) using oscillator signals from an oscillator (OST) of the respective transmitter (Tx), wherein the converted signals are transmitted as the radar signals (RS).In step b), the respective receiver (Rx1, Rx2, Rx3) receives the radar echoes (RE) of the radar signals (RS) from the respective transmitter (Tx) and performs phase-preserving modulation (MOD) using the received radar echoes (RE) or processed radar echoes (RE'), and sends the resulting modulated signals (MS) to the signal processing platform (SP). In step c), the signal processing platform (SP) demodulates the received modulated signals (MS) and performs a fourth frequency conversion (CON4) of the demodulated signals (DS) into the base frequency band (BB) using oscillator signals from the oscillator (OST) of the respective transmitter (Tx), thereby obtaining raw SAR data (RD) from which the signal processing platform (SP) generates and stores digital data.