Shipping Radiated Noise Estimation Techniques.

Passive sonar's primary function is to detect a target against background noise and underwater sound propagation losses. Sonar performance modeling is essential for effective deployment, focusing on a detailed analysis of the Passive Sonar Equation terms (Source Level, Noise Level, TL, Array Gain). Key to this is the ROC curve, which establishes the crucial trade-off between the probability of detection and the probability of false alarm, enabling the calculation of the Detection Threshold (DT).

The effective detection range is found by linking the DT to the Transmission Loss (TL) curve. For the IOR, the RAM (Range Dependent Acoustic Model) based on the Parabolic Equation (PE) approach is recommended for low-frequency TL modeling. The article highlights the importance of accurately modeling shipping radiated noise (using models like Wittekind) based on AIS data to create comprehensive ambient noise maps. By combining these noise and TL data, a 3D SNR map can be developed to guide tactical decision-making, offering a complete understanding of where detection is most likely. Challenges include the IOR's unique environment, model accuracy in the low-frequency range, and the need for policy to manage underwater noise for the protection of marine life.

• Automatic Identification System (AIS): It is a tool for identifying and monitoring maritime traffic by sending and receiving vessel information to nearby ships and coastal authorities on two dedicated VHF radio frequencies
• Considering the dominant contribution of ships in the low frequency ambient noise levels of the ocean, estimation of shipping noise levels has been an important aspect from both marine conservation as well as national security perspective
• The shipping noise estimation techniques as well as its applications have evolved with advancement in technology. The technique now has relevance to multiple military and non-military applications across multiple stakeholders.