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LFAPS

The LFAPS project was to build a multi-mode low frequency sonar system for the Australian Navy in conjunction with a number of local and overseas companies. The prime contractor was
Thales Underwater Systems

The LFAPS system consisted of a sonically steerable sonar receiver, a sonically steerable sonar transmitter, and a set of deployable sonar-buoys (essentially a free standing marine sonar receiver).

The implementation was a success with two world firsts for Australia. The results from the field trials of this system were also astounding from my point of view. The three points that stand out in my mind showing the effectiveness of the system was:

  1. During a set of war games of the east Australian coast, Two frigates were given the task of destroying each other. One was equipped with the Sonar system, the other was not. The ship with the sonar system not only detected it's sister ship, which was trying to hide within a fleet of container ships, but launched attack helicopters that effectively destroyed the ship before the sister ship located it's own target.
    The ship fitted with the sonar system was much more effective in simulated battle conditions
  2. While testing and co-ordination tasks were being being carried out on the west coast of Australia, container ships were being detected traveling up and down the east coast of Africa. Now container ships are notoriously noisy vessels but then again the east coast of Africa is some thousands of miles away.
  3. End-of life tests were being carried out in order to determine how the signal degrades over time. During these trials it was suspected that a American nuclear submarine was traveling south past the west Australian coast. Once detected this submarine was followed for some time.

The technical challenges in the project was the integration of all components such that they enhanced the overall reception of data. The pulses from the transmitter were received by both the steerable receiver and the sonar-buoys. The system consisted of 5 separate processors interconnected by an multicast ATM Network.

Our initial involvement in the system was to be integrate the entire system. This, however, quickly led to rewriting aspects of the system in order to write missing components or to repair deficiencies in the existing system. Our involvement in the project then was was co-ordination of all third-party subcontractors as well as the in-house software and final certification of the system and general trouble-shooting.

This led to extensive rewrite of:

  • A device driver for the data acquisition from the hydrophones.
  • A device driver for the control of the sonar transmitters.
  • A device driver for reading ship specific data (heading speed etc).
  • A device driver for the control of a high speed tape data storage system (tape).

    • as well as miscellaneous support code, control gui's and test software and harnesses. Each node consisted of a VME based power PC using the Lynxos real-time operating system including an ATM card and drivers.

    Each node then had additional hardware and suitable drivers suitable for each nodes specific task.