The analog multiplexer provides a method of recording six analog signals (by means of 

 time sharing) on three channels of the recorder. Two signals are fed into one section of the 

 multiplexer, where the signals are alternately switched to a single output line. The time each 

 signal is on line is adjustable from the front panel. 



The 6-channel strip-chart recorder provides a time-history ink trace of the nine BIAS 

 buoy measurements (six channels time shared and three channels direct). Each channel of 

 recording is 40-millimeters (mm) wide scaled into 50 units providing a reading resolution of 

 one-half percent of full scale or one-fifth mm. The chart speed is incrementally adjustable 

 from one mm per minute to 125 mm per second. 



The 36-volt power supply, adjusted to 30 volts, is used to power the servo motor in 

 manual-mode operation and to power the servo amplifier in the automatic modes of operation 

 of the depth control system. 



The 60-volt, 500-milliampere d-c power supply, adjusted for a constant current of 135 

 milliamperes, provides power to all the measurement electronics in the buoy. 



AUTOMATIC DEPTH-KEEPING SYSTEM 



The BIAS buoy is fitted with a horizontal stabilizer which is adjustable through a range 

 of incidence angles from 15-degrees leading edge up to 15-degrees leading edge down. A d-c 

 servo motor. Globe Industries, Model 43A152-7, located in the center vertical fin, actuates 

 the horizontal stabilizer through a 10 to I worm-gear ratio. A potentiometer which serves as 

 the stabilizer-position sensor is geared to the servo motor output shaft. Two micro switches 

 actuated by a cam mounted on the servo motor shaft limit the stabilizer to plus or minus 

 15-degrees rotation. The mechanical arrangement of the above equipment is shown on 

 DTNSRDC Drawings E-2773-13, -14, and -16. 



The servo motor is electrically driven by a servo amplifier (WESTAMP, Inc., Model 

 A457) located in the data center buoy control unit; interconnection is provided by two leads 

 in the towcable. The servo amplifier is a linear d-c power amplifier with three summing 

 inputs. The three buoy sensor signals of shallow depth, stabilizer position and pitch (which 

 is differentiated to produce pitch rate) are obtained from the output of the discriminator 

 unit in the data control center. The three buoy sensors are described in the Buoy Evaluation 

 Measurement Systems section. These sensor signals plus a manually-controlled depth-selection 

 signal are connected to the inputs of the servo amplifier which drives the servo motor and 

 completes the servo feedback loop. A Philbrick Chopper Stabilized Amplifier Model P656 

 is used as part of the pitch differentiating circuit. 



The d-c servo amplifier is powered by a 28-volt d-c, I -ampere Kepco Power Supply 

 (Model SC-36-1M) located in the data control center. 



19 



