AN UNDERWATER COMMUNICATION SYSTEM UTILISING SONAR AS THE CARRIER MEDIUM. PROVIDES SIMPLES COMMUNICATIONS BETWEEN THE VESSELS BY THREE DIFFERENT MEANS: SONAR SIGNALS. SLOW SPEED TELEGRAPHY (SST) BY MORSE KEY. SPEECH. IT OPERATES ON A STANDARD SONAR CARRIER FREQUENCY; THE DATA TO BE TRANSMITTED MODULATES THE UPPER SIDEBAND WITH THE CARRIER BEING SUPPRESSED. IT IS COMPATIBLE WITH ALL UNDERWATER TELEPHONES. IT HAS BEEN DESIGNED TO BE USED WITH VARYING COMPLEXITY DEPENDING ON THE TYPE OF VESSEL. THE TRANSDUCERS ARE ARRANGED IN ARRAYS OR USED SINGLY: -NAROW BAND SERVO CONTROLLED TRAINED ARRAY. - OMNI DIRECTIONAL FIXED ARRAY. - SINGLE BROADBAND TRANSDUCER. USERS CONTROLS ARE GROUPED ON THE ACOUSTIC LINK CONTROL UNIT (ACLU) AND THE TRAINING CONTROL UNIT (TCU), WHICH ARE LOCATED IN THE CONTROL ROOM ON SUBMARINES.

CLASSIFICATION HAS BEEN DETERMINED IN ACCORDANCE WITH THE FOLLOWING:- GENERAL INTERPRETATIVE RULES (GIR)S GIR 1 HAS BEEN USED TO CLASSIFY THIS PRODUCT BY THE TERMS OF HEADING 9014 - DIRECTION FINDING COMPASSES; OTHER NAVIGATIONAL INSTRUMENTS AND APPLIANCES. GIR 6 HAS BEEN USED TO CLASSIFY THE GOODS TO SUBHEADING LEVEL 901480 - OTHER INSTRUMENTS AND APPLIANCES . ALSO CLASSIFIED IN ACCORDANCE WITH:- HARMONISED SYSTEM EXPLANATORY NOTE (II)(B) (7) TO HEADING 901480