Introduction
Enemy or terrorist divers can pose serious threat to sensitive installations, naval and commercial ports, critical infrastructures (such as power plants), naval vessels, superyachts, cruise ships, LNG terminals, etc. Smuggling operations are also reportedly carried out by divers.
In the past decades, the potential threat posed by enemy divers has been enhanced by the most recent advancements in the areas of underwater navigation technology, personal mobility and underwater communication technologies.
Diver Detection Sonars (DDS) are acoustic devices which, when coupled with a proper specialised software, are used for detection, tracking and classification of divers and submerged diver/swimmer delivery vehicles (DDVs / SDVs).
Time is of the essence. The capability to alert the security personnel in time for their intervention is crucial. The critical information delivered by the DDS is the classification of the type of threat (closed/open circuit diver, underwater vehicles), direction of the threat, speed, bearing and estimated time to target.
Diver Detection Systems serve a variety of underwater security applications, primarily offshore installations, ports, coastal and river facilities, ships and pipelines. The noise in the signal caused by passing vessels, large sea mammals, or schools of fish makes the job of the tracking software particularly difficult when the goal is to create the minimum number of false alarms.
GuardPoint Tracking Software for Intruder Detection
NORBIT’s GuardPoint Tracking Software is designed to detect, track and classify divers and underwater submersibles. It can be interfaced with all a wide variety of sonar heads at different frequencies to adapt to different environments.
Single or multiple sonar heads (GuardPoint 70, 100, 200 and 400) are interoperable in a variety of configurations to adapt to different environmental conditions.
GuardPoint 70 Sonar provides long-range detection and tracking of underwater targets in open waters. GuardPoint 400 having higher frequency, provides better detection performance in shallow waters.
Diver Detection Tests in Shallow Waters
NORBIT conducted a test with the Armed Forces of a NATO country to test the capability of GuardPoint Tracking Software and GuardPoint 400.
The test was carried out next to the Special Forces and the Army Helicopter Base and in very shallow waters of a river where depth is only between 1 and 2 m and visibility is only 5 to 10 cm. The use of GuardPoint 400 was preferred because of the shallow water conditions.
During the tests, the Special Forces and Army deployed both open and closed-circuit divers for a variety of test scenarios run in daytime and at night.
Since the area presents many disturbances, including high level of surface, bottom and volume reverberations and high shipping density, this was the perfect simulation of a possible real-life application of the system.
Preparation
- Bathymetric site survey using NORBIT iWBMS Multibeam Sonar and iLIDAR Laser Scanner
- Sound speed profile measurement for sonar performance prediction
- Pier installation
Diver Detection and Tracking Test
Performance Prediction with NORBIT NORTrace
Performance of a sonar can vary -even on a daily basis- depending on environmental conditions (e.g., temperature, rain, salinity). NORTrace is a sonar performance prediction software that estimates sonar signal propagation underwater with given environmental parameters. Prediction is based on Ray Theory with validated Noise, Sonar, Target and Environment models. We used NORTrace to estimate range and probability of detection to optimise sonar parameters and deployment depth.
GuardPoint Displays The Area Monitored
The image below shows the area of the river being monitored, together with the overlayed sonar images.
Adjustment Cross-Check
Checking sonar settings using both Sonar User interface (left) and GuardPoint User interface (right).
GuardPoint Tracking Software automatically marks classified divers with a white square box on an automatically positioned range and bearing with a uniquely given ID. Also track trajectory is marked to indicate the latest positions where divers were underwater.
GuardPoint Tracking Software outputs the position of the diver, the direction and the estimate of the time to reach the sensitive point. The response team has all the information needed to intervene on time and to prevent a breach.
Results and Conclusions
Conclusions:
- Underwater threats were automatically detected, tracked, and classified in a challenging environment, with very low false-alarm rates.
- GuardPoint 400 + GuardPoint Tracking Software demonstrated to be a lightweight, portable system that supports rapid, easy installations for underwater surveillance.
- NORBIT’s GuardPoint Software was straightforward to operate, even for operators not familiar with sonar operations.
- Several display formats are available, assisting the sonar operator with a better interpretation and localisation of the threats.
- No internet connection was required during the operation to maintain a “Stealth” and “Secure” operation and data processing.
