Avoidance of Sonar Array Ambiguity
Abstract
The response of an electrically steered linear array of omnidirectional sensors shows two ambiguous beams. Cross-fixing with two such arrays can lead to multiple choice with up to four possible target positions, so we try here to find the best relative orientation for the arrays. Consideration of the areas of unambiguous cover clearly shows this best orientation to be a right angle, with a steady deterioration as the parallel arrangement is approached. Building up the right-angle forms into crosses shows that cover is good for the so-called Potent Cross, Fylfot and Swastika but poor for the Greek Cross. With larger fields of arrays the Fylfot field is very well behaved indeed, but the Potent Greek is undesirable. Very near a coast some tracks are implausible, and the best arrangement for a pair now involves that array lying next to the coastline being parallel to it, with the second array pointing at the first. With a curved array the directional ambiguity is reduced, the effectiveness in removing it varying as the array width measured in wavelengths. Instead there is sometimes a focusing ambiguity, and it pays to put the concave side of the array facing the direction of greatest interest.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1976
- Accession Number
- ADC950446
Entities
People
- D. E. Weston
Organizations
- Admiralty Research Laboratory