Originally conceived in 1990, the Model 855 family of sonars was the first sonar system family from Imagenex. The Model 855 sonar processor unit can operate any of the impressive variety of Imagenex Model 855 sonar heads. There are many standard and customized head configurations available, including rotary units in imaging, profiling, tilting head, and miniature formats. An excellent sidescan sonar towfish unit is available, and there is a special two-axis "searchlight" style head designed for the inspection of storage tanks and salt caverns. Available acoustic frequencies range from 150 kHz to 2.25 MHz.
The Model 855 processor provides power and communications to the sonar heads, and displays the incoming data on a standard computer monitor. The processor can store analog data to Digital Audio Tape (DAT) which allows full featured, high resolution playback, and can be configured for normal (600 m) cable or optional long (up to 3000 m) cable lengths.
Applications of rotary sonar units include inspection of water-works, large storage vessels, and mounting on ROV's for monitoring operations. Sidescan units are used for salvage and underwater searches.
The Model 858 sonar processor was designed as an upgrade to the Model 855 sonar processor, adding the convenience of digital recording to an external SCSI disk drive, interface to popular thermal chart recorders, and incorporating a Track Plotter for GPS ships position display.