• Home
• Featured Products
  • Radar & Remote Sensing
  • SAR Simulation Toolbox
  • Geospatial Intelligence SAR Toolbox
  • Tri-Mode SAR Processor
  • SMOS Processor
  • Sonar
  • Acoustic Signature Classification Database
  • Sonar Post Analysis System
  • High Fidelity Sonar Simulator/Trainer
• Core Business
  • Sonar
  • Radar and Remote Sensing
  • Intelligent Transportation Systems
  • Software Defined Radio
  • ADCON System
• Careers
• About Us
  • Contact Us
  • Corporate Overview
  • Executive Biographies
  • Quality Standards
  • Careers
  • Certifications
  • Privacy Policy
  • Site Map

SARSAT - Search and Rescue Satellite Aided Tracking

Array's SARSAT processing is available for ground station upgrades, or as an emergency on-call analysis service to assist rescue teams in the field. Our past experience with signal processing includes successfully completing a contract for Defence Research and Development Canada-Ottawa (DRDC-Ottawa) (formerly DREO) to develop a new emergency locator signal processor for the Search and Rescue Satellite Aided Tracking (SARSAT) system (also known as COSPAS).

The SARSAT system supports the detection of Emergency Locator Transmitter (ELT) signals and relays them to a Local User Terminal (LUT), which acts as a ground station. By calculating the doppler frequency shift of the ELT signal, the LUT can provide an estimate of the ELT position to search and rescue authorities.

Array's novel strategy combines elements of digital signal processing, image analysis, and pattern to detect and use signals that are missed by the current system. ELT performance is also not standard - Array's approach targets and augments data even from the fault-prone ELTs. Restored carrier signals are then evaluated using advanced filter techniques to pinpoint the emergency site.

Current problem areas include:

• Missed ELT detections
• Position determination errors
• Multiple false alarms for non-existent ELTs

An End to Throwaway Hardcopy Dot-Plots

The baseband version of the 121.5 MHz signal SARSAT has a bandwidth of about 25 KHz and is effectively sampled at a rate of 64 KHz. The input signal is stored in a temporary buffer and processed at the digitization rate. As the originally implemented SARSAT LUT did not have adequate storage capacity to store all the raw data, the raw data were processed to reduce the volume to a level that could be stored.

The storage capacity was only large enough to store the Dot Plot of the raw data, so the system generated the Dot Plot in real-time. Today, data storage is cost-effective, and information from one or more satellite passes can be collected, digitized and subjected to analysis.

Our Enhanced Signal Processor Algorithm

Array's method of SARSAT data processing significantly improves the SARSAT Dot Plot data. The ESP algorithm provides the following combination of methodologies and techniques:

• Longer Fast Fourier Transforms (FFTs)
• Doppler shift reduction
• Herringbone detection
• Carrier reconstruction
• Background noise suppression
• ELT identification

New GUI and Tools

Users can view all or part of the dot plot data, either in conventional format or greyscale when they are processing data on a commercial workstation. They can also see the signal characteristics (signature) of the ELT associated with any dot plot curve. This function allows immediate association of curve segments broken up by physical or electromagnetic interference.