F-5 



Two diffusion experiments in the Pacific and a study in Puget Sound to 

 measure tidal flushing of a bay for a proposed nuclear power plant. 



All data are recorded internally on magnetic tape; some oceanographic 

 and vehicle operation data can also be telemetered to the ship acoustically. 



The data are converted to binary form and are sampled periodically. 

 The more important data are sampled 12 times a second and most of the 

 oceanographic data are recorded at this rate. Vehicle data are sampled 

 at rates varying from 12 times a second to once a second. 



There are several ways to display the data for study and analysis. 

 In the older method the tapes are read directly into a photosensitive 

 paper strip recorder. Vehicle tapes are also transferred to computer- 

 compatible tapes, after which the data can be printed out or plotted using 

 the IBM 1130 computer and its peripherals. 



Tracking : Frequency diversity and frequency shift keying (FSK) are used 

 in the tracking system. Transmission to the vehicle is at 20 and 22 kHz 

 and the vehicle replies at 26 and 28.9 kHz. The lower frequency in each 

 case is used for a in the digital word. The frequency diversity pre- 

 vents crosstalk problems when more than one device is being tracked. 

 Although this system gives good performance with signal-to-noise ratios 

 down to 6 dB, it is susceptible to multipath propagation. 



The structures of the transmission and reply are as follows. There 

 are 25 bits in a word, each bit 1 msec in length. The first 8 bits are 

 used only for the correlation code which is used to accurately time the 

 data loading. Bits 11 and 12 are identity or address bits which are used 

 to permit selective tracking of up to k objects other than the vehicle. 

 (Bit 9 alone serves as an identity code for the vehicle.) The command 

 bits 13 through 2^ are binary-coded with the most significant bits 

 sent first. Bit 25 is a parity error-detection bit which Is chosen so 

 that there are an even number of I's In the bits following the correla- 

 tion code. If the parity of the command as received does not agree with 

 the parity bit the command will not be stored or executed. Although 

 every transmission to the vehicle Includes command bits they usually 

 simply reiterate the operating depth (D2, D3, or Bh) , and are essentially 

 tracking pulses. 



The reply code correlation and Identity bits are the same as in 

 the incoming transmission but telemetered data bits replace the bulk of 

 the command bits. 



Launch/Retrieval : A launch/retrieval crane is bolted and welded to the 

 ship's railing and deck. Its boom has a reach of 5m (16 ft) from the 

 side of the ship, its whip is 9ni (30 ft) long and its capacity Is 90Tkg 

 (2000 lbs) at full reach. 



For launch the vehicle Is held a few feet above the surface by a 

 launch bar which is tripped with a line from the deck. The vehicle is 

 dropped with the ship underway at about 2 knots (i+km/hr). On the vehicle's 

 return to the surface the ship is maneuvered to within about 100m (328 ft) 

 and the crane is used to launch the boat ; the crew attaches the recovery 

 bridle, tows the vehicle into range and attaches the crane's whip. With 

 the boom fully extended the whip is used to pull the vehicle toward the 

 ship with the boat crew stabilizing the operation. When the vehicle is 



