The N456 Navigator system

Abstract

The N456 Navigator has been developed to assist in Long Baseline (LBL) acoustic navigation. Its two basic functions are generation of acoustic signals, and receipt and timing of returns. When combined with the new dsnav software this becomes the basic component of an LBL navigation system. The principal motivation for this development was as a replacement for the Benthos 455 Acoustic Signal Processor and the Alvin's NavBox. The N456 is intended for use in the Jason Control Van, in the Alvin submersible, and in the Atlantis TopLab. Enough flexibility is built into this system to be able to interface with a wide variety of ceramic transducers, or with an EDO 5400 Underwater Telephone. Through the hardware and software of the system a series of pings is generated, which are used to interrogate underwater vehicles, instruments, or transponder nets. Once pings are generated, transponders or vehicles, hear them and may respond with pings of their own. The basic LBL function is based on timing the receipt of these responses, calculating the distance the transponders or vehicles (by knowing the speed of sound), and calculating the best-fit location.