K[X(D + AZ) - X(ZC + AZ)| 

 X(C, + AZ) - X(C2 + AZ) 



K (D - ZC) 



Thus the angular measurement is independent of long-term zero and sensitivity shifts in the 

 data transmitting electronics or recording instruments. Tiie only requirement is that the 

 cahbration sequence and data points remain within the bounds of the recording scale. 



CONCLUSIONS 



Based on the results of the development-assist trials on a submarine, the following 

 conclusions are drawn. 



1 . The BIAS buoy evaluation measurement system adequately furnished all of the 

 recorded measurement parameters required for evaluation of the BIAS buoy system. These 

 parameters included: buoy pitch, horizontal stabilizer angle, depth (shallow and deep), cable 

 tension at the submarine, cable scope (fine and coarse), submarine depth, and speed. Tlie 

 overall accuracy of measurement was approximately one percent of full scale, except for 

 cable tension which was approximately 5 percent, or essentially that of the individual sensors 

 involved. 



2. The automatic depth-keeping system, used in conjunction with the above measure- 

 ment system, showed little if any improvement over the inherent surface following charac- 

 teristics of the buoy. At the deeper depths (20 feet) an improvement in long-term towing 

 was realized wherein the automatic depth-keeping servo would hold the buoy at a constant 

 depth even though the submarine speed or depth varied somewhat. However, a greater cable 

 scope would be required to compensate for increased speed or increased deviations of sub- 

 marine depth. 



3. The buoy operational measurement system provides all of the measurement param- 

 eters necessary for operation of the BIAS buoy system wiiile on patrol. The measurement 

 parameters, displayed as meter readouts, include: buoy deep and shallow depth, fine and 

 coarse cable scope, and cable tension. The overall accuracy of this system was determined to 

 be approximately 5 percent of full scale. 



33 



