SSAR-ADM - Spotlight Synthetic Aperture Radar Advanced Development Model
Developed to augment the existing capabilities of the CP-140 AN/APS-506 radar with a long-range imaging capability for classifying and identifying surface vessels
The SSAR technology is licensed to Array for commercialization as Array’s TriSAR product
The CP-140 Aurora serves as the Canadian Forces' Maritime Patrol Aircraft (MPA), flying Anti-Submarine Warfare (ASW), Anti-Surface Warfare (ASuW), and area surveillance missions. To support these missions, the Aurora is fitted with an avionics suite that includes an AN/APS-506 radar. The AN/APS-506 is a high power, high scan rate, medium Pulse Repetition Frequency (PRF), pulse compression radar which operates at X-band frequencies. This radar is the primary non-acoustic sensor on the Aurora, and gives the CP-140 operators the ability to detect periscopes and snorkels, surface vessels, and to survey land and sea areas. It also helps the crew navigate the aircraft, and avoid severe weather.
The purpose of the SSAR ADM project was to augment the existing capabilities of the CP-140 AN/APS-506 radar with a long-range imaging capability for classifying and identifying surface vessels.
SSAR ADM system development included four key activities:
- Upgrading the AN/APS-506 radar set components to support coherent SAR operation.
- Adding a dedicated SAR console including keyboard and monitor.
- Adding dedicated motion sensors to support SAR data motion compensation.
- Adding dedicated SAR processors and data storage devices.
The new SAR processors include a SAR Radar Correction (SRC) unit to perform SAR data collection, and a SAR Processor (SARP) WRA, to carry out SAR motion compensation and SAR signal and display processing. The SSAR ADM development also enhances the capabilities of the existing AN/APS-506 Digital Signal Data Converter-Storer (D/SDC-S) by adding a function to control AN/APS-506 radar set components. The resulting upgraded D/SDC-S processor is referred to as the Data Scan Controller (DSC).
Array developed the SARP WRA, as well as the upgrade to the D/SDC-S that allows it to control the radar set components, the DSC WRA.
The SARP WRA has three high-resolution imaging modes: Spotlight mode, Range-Doppler Profile (RDP) mode and Strip-Map mode. Spotlight mode produces an image snapshot characterizing the radar cross section of a target as a function of range and cross-range displacement, and operates in near real time. RDP mode produces an animated image of the target in which radar cross section is displayed as a function of range and Doppler frequency, and updated in real-time. Strip-Map mode produces a real-time map of a designated ground swath that scrolls across the operator's monitor.
The Motion Compensation (MC) software calculates the degree of deviation between the Antenna Phase Center (APC) trajectory and the ideal trajectory assumed by the SAR imaging algorithm. The calculated deviations can be used to correct for phase shifts in the radar return. The MC in SARP implemented the following calculations:
- APC position and velocity
- Pulse Repetition Interval (PRI)
- Range Delay Adjustment
- Antenna Azimuth and Depression Angles
The SARP also allows storage of raw data as well as motion compensated data, and raw data reprocessing in an off-line mode. SARP also implements a SAR console to control data acquisition, SAR processing parameters, system diagnostics and the display and manipulation of SAR images.
Upgrading the D/SDC-S involved programming for the 1553B with the DSC as the bus controller and SARP, D/SDC-S, and SRC as bus terminals. This process also identified and implemented messages to ensure correct operation of the radar and data collection functions in both conventional and SAR modes. The SARP received EGI data over the 1553B.
Under this contract, Array developed a testbed for integration and testing of the SARP. This testbed consisted of a 1553B simulator, SRC simulator and tools to generate SAR raw data. The 1553B simulator served as the D/SDC-S and the SRC for the SARP development, and it served as the SARP and SRC for the D/SDC-S development. This allowed Array to exercise all the messages and radar control over the 1553B.
Array used Ada and C as the development languages, and VxWorks and MCOS were the real-time operating systems. Software development took place in the Rational Apex software environment. Array developed the firmware as well as the software. This included programming the FPGAs for the IMU interface module and for the Zero Range Trigger (ZRT).