Real-Time Synthetic Aperture Radar Processing System and Method
|507 - Abstract:|
|The European Space Agency offers a real-time SAR processing system of SAR raw data. The image processing is performed by optical means without the need for high performance computers. No chemical film processing is necessary, no moving parts, and no reusable photosensitive materials are required, leading to an enormously improved system durability. ESA is seeking companies interested in a license agreement.|
Description of the offer:
Synthetic aperture radar (SAR) is a technique widely used in aerial and space reconnaissance. An air- or spacecraft carries a side looking antenna and transmits radar pulses in a direction different from the flight path. A slant range coordinate is defined in a direction normal to the flight path and an azimuth coordinate is defined in the direction along the flight path. As the range resolution of the SAR is a function of the effective transmitted pulse width, high resolution in range is achieved by the use of very short transmitted pulses (or chirped pulses). The azimuth resolution is set by the dimensions of the antenna and therefore limited by the size and weight of the antenna carried by the air- or spacecraft.
However, applying a specialized signal processing technique, a high resolution in the azimuth direction is attained without the necessity of physically large antennas. In effect, a large aperture antenna is synthesized. Thus, a coherent phase history of the pulse return signal is generated and recorded. This requires large data storage and huge data processing capabilities.
In a conventional optical processing system, the raw SAR data is recorded on a photosensitive material (film) for storage and subsequent optical processing. The film recorded during the acquisition must be (chemically) developed. This prevents real-time processing and requires chemical film treatment that usually cannot be performed in an air- or spacecraft. Also, due to the large amount of data involved, on-board processing on satellites is usually not possible. Furthermore, the large amount of uncompressed data needs to be transmitted to a ground based processing centre. This requires large bandwidth for the data transmission.
It is an object of the offered technology to provide a real-time SAR processing system and method with reduced data processing requirements and enhanced durability. The present technology replaces the films used in the conventional SAR technology with new technologies such as a spatial light modulator (SLM) or micro display and a light sensitive sensor (CCD or CMOS). This allows an on-board real-time processing in air- and spacecrafts and reduces the data amount to be transmitted to ground stations to a great extent and, thus, bandwidth costs.
The real-time SAR processing system for processing SAR return signals comprises:
- A light source (laser) for generating a coherent electromagnetic wave
- Light modulation means (comprising a plurality of addressable pixels) for modulating the incident wave (phase and/or amplitude) according to radar return signals and outputting a modulated wave
- Optical processing means (suitable lenses) for processing the modulated wave for radar image reconstruction
- Light detection means for detecting the processed wave and generating a corresponding electrical processed image signal. This analogue or digital signal may be stored, compressed and/or transmitted to a ground station
Innovations and advantages of the offer:
The synthetic aperture radar (SAR) processing system according to the offered technology has the advantage that it allows a real-time processing of the SAR raw data. The computation intensive image processing, such as the Fourier transformation, is performed by optical processing means, doing away with the need for high performance computers. The electrical radar response signals are input into the optical processor by light modulation means and no chemical film processing is necessary so that the system may be permanently deployed in an air- or spacecraft. The durability of the system is enormously improved and since the reconstructed image of the radar target areas is converted to an electrical processed image signal, it can be easily processed by conventional analogue or digital signal processing techniques.
Domain of Application:
- Data Communications
- Satellite Microwave Communications
- Other Communication Related
Last update: 15 January 2013