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To all: I have seen some recent mentions that hope is being placed in the sonar now under development that could allow for better navigation while the water visability is less than desired. There are but two basic sonar systems. Active and passive. Depth sounders, fish finders, and side scan sonars all fall under the definition of active sonar. In this type of system, an active "ping" or transmission is induced into the water. The electronics keep track of the time interval from the time of transmission is produced until the return or echo is heard back. This echo represents this sound having struck an object be it rocks, sand, kelp, fish, boats, or whatever. The speed of sound in water can vary due to salinity, degree and pressure, but is predictable. It is simular to counting the seconds after a thunder clap to determine the distance to an aproaching storm. It is in this way, an active sonar can determine the distance of a detected object. (although performing this feet is obviously much harder to perform) Passive sonar is as if you dunked your head underwater and simply listened. Only those objects such as boat propellors, some aquatic fish, rain storms, earthquakes and such will be picked up on. I remember a 688 fast attack that ran into an underwater sea mount off Guam...why? no active sonar was being deployed and mountains do not in themselves make noise. I would venture to say concidering the extensive damage and the loss of I think one sailor, the Navy knows this mount exists now! The sonar system now under investigation is being made to study and eventually deploy an underwater communications capabilty as well as provide PSUBS with an affordable passive or listening sonar capability. It is in no way designed to aid those baots submerged and in close to zero visability with the ability to navigate for the purpose of avoiding close abord objects detected during near bottom high speed transits. Just thought I would break to you this bit of bad news. David Bartsch Alert and listening and wired for sound. Be the filmmaker you always wanted to be—learn how to burn a DVD with Windows®. Make your smash hit |