A twofold effort is presently directed toward improving the efficiency of the 50-kc 

 portion of the system. First, a new projector that resonates at 50 kc is under design to pro- 

 vide a more efficient transfer of power. Second, a solid-state power amplifier is being de- 

 signed with the net result being a smaller, more efficient, and more reliable 50-kc transmitting 

 capability. 



Future plans to improve the usefulness of the system for its intended applications, i.e., 

 helping in data reduction and providing navigational aid, consist of expanding the laboratory 

 portion of the system to a capability of handling data from six hydrophones simultaneously. 

 To work in conjunction with the expanded system, plans are underway to provide an analog 

 voltage that is proportional to range for each data hydrophone. This analog voltage will serve 

 the prime function of supplying range information to the automatic data processing equipment 

 so that on-line analysis may be accomplished. To increase the usefulness of the system in 

 providing navigational aid, a range readout on the submarine would be of great value. To 

 provide such a readout studies and tests are contemplated to determine the optimum frequency 

 of operation, power required to transmit the information, and the best format of transmission 

 for minimum error. 



EVALUATION RESULTS 



Numerous submarine acoustic trials and system evaluation tests have shown that the 

 ranges obtained are both reliable and repeatable to ranges exceeding 5000 yd when using the 

 submarine's AN/UQC-IA as the acoustic sound source. The capability of transmitting acoustic 

 energy at 50 kc is a recent addition to the system, but preliminary field tests with surface and 

 subsurface craft have shown that ranges can be obtained with the same degree of accuracy and 

 reliability to a range in excess of 1500 yd. 



Preliminary evaluation tests were made employing two surface ships. One of these 

 ships simulated the target, the other the laboratory ship. The target ship made runs past the 

 listening ship at various speeds to determine signal-to-noise ratios and true signal recognition 

 ability. Static drifting tests were conducted where ranges were checked by a high accuracy, 

 recently calibrated radar, and close ranges, i.e., less than 1000 yd, were checked with a 

 statameter as well. The agreement between these methods was very good. 



As with any system, the final evaluation must be conducted under actual working con- 

 ditions. The ARMS was put aboard a submarine for test purposes during an actual acoustic 

 test. The first results, although favorable, showed areas where improvements were needed. 

 As the improvements were implemented, the dependability of the system was improved. The 

 ranges from the system were then supplied to the submarine as an aid to navigation with the 

 result that the quality of the acoustic trials was greatly increased. The greatest improvement 

 was in the number of runs that did not have to be repeated because of navigational errors. 



Several methods have been employed somewhat successfully to synchronize the two 

 portions of the system. The two methods retained have the disadvantage of requiring the 



11 



