The electronics of the buoy are energized by a d-c power supply (located in the data 

 center) via the same conductor used for data transmission. The a-c composite datum signal 

 is decoupled from the d-c supply by an inductive-capacitive network at each end of the 

 towcable. 



During preliminary sea trials it was noted that the telemetry signal was interfering with 

 VLF reception. As a consequence, a modification was made to the instrument system which 

 permits shutdown of the telemetry portion but still allows buoy depth datum transmission to 

 the data center. Telemetry cutoff is accomplished by remote control of a relay in the buoy 

 which interrupts the supply voltage to the VCO's. The two depth-sensor d-c outputs are 

 summed and the summed signal is converted to a d-c current signal for transmission to the 

 data center on a separate lead within the towcable. 



To complete the buoy-towcable measurement requirements there are four measurements 

 made from sensors mounted in the buoy nest area aboard the submarine. These parameters 

 are cable tension, submarine depth, fine cable scope, and coarse cable scope. 



The cable tension sensor, a four-arm strain gage bridge, is directly wired to the data 

 center via four conductors. The remaining sensors are potentiometer-type gages which also 

 are direct wired to the data center. Each sensor is interwired into a calibration network 

 similar to that described previously. A multiple-rotary-solenoid switch and sequencing 

 network, identical to the one in the buoy, is operated from the Cal-Start pushbutton on the 

 front panel of the data center control unit. 



The four direct-coupled sensor outputs (or cal signals) are input to the strip -chart 

 recorder for time-history readouts. A submarine speed signal is provided by the ship's 

 electromagnetic log and is recorded with the above parameters. 



As may be noted there are nine parameters to be measured. Because of the limited 

 space in the submarine, a small, six-channel strip-chart recorder was used. Therefore, a three- 

 channel multiplexer or time-sharing instrument was fabricated at the Center to allow three 

 groups of parameter pairs to be recorded on three recorder channels. The three paired param- 

 eters are: fine cable scope and coarse cable scope, deep buoy depth and shallow buoy depth, 

 and buoy pitch and horizontal stabilizer angle. Submarine speed, submarine depth, and tow- 

 cable tension are recorded separately on the remaining three recorder channels. 



AUTOMATIC DEPTH-KEEPING SYSTEM 



To determine the feasibility of automatic buoy depth control, a servo system to auto- 

 matically control buoy depth via actuation of the buoy horizontal stabilizer was designed and 

 manufactured as part of the BIAS buoy program. A photograph of the BIAS buoy is pre- 

 sented in Figure 4, which shows the arrangement of the tail assembly which consists of 

 vertical fins and a horizontal stabilizer. 



