housing the electronic units 
CONCLUSION 
This paper has been concerned with a 
combination precision depth meter and bottom 
survey instrument, with provision for also 
transmitting sound velocity information to the 
surface. Since velocity information is not 
complete without a precise depth measure- 
ment, and since the depth measurement 
becomes far more accurate when the true 
velocity is known, these two instruments 
complement each other rather nicely. How- 
ever, to complete the velocity picture the 
factors which affect velocity should also be 
known. Therefore, we are now preparing to 
add precise temperature determination and 
possibly salinity to the velocity and depth 
determinations. 
ACKNOWLEDGMENTS 
This gear was developed under Office of 
Naval Research Contract No. 1367. 
The authors of this paper wish to thank 
J. B. Hersey for promoting and supporting 
the development of the equipment. 
They also greatly appreciate the coopera- 
tion and assistance of Earl E. Hays who 
developed successful techniques for using 
the gear as a survey instrument for detailed 
examination of the bottom. 
This is Contribution No. 
1222 of the 
Woods Hole Oceanographic Institution of 
Woods Hole, Massachusetts. 
LIST OF FIGURES 
Fig. 1 Block diagram of system components. 
IDiiery He PGR record of typical lowering(photo). 
Fig. 2 Schematic diagram of transmitter. 
Higa Schematic diagram of receiver. 
Fig. 4 Structure of deep unit (photo). 
Fig. 5 External view of watertight compart- 
ments (photo). 
Fig. 6 Transmitter chassis. 
Fig. 7 Receiver and velocimeter amplifier 
chassis (photo). 
Fig. 8 Bottom view of receiver and 
PRINTER 
LOW PASS 
FILTER 
PRECISION 
GRAPHIC 
RECORDER 
velocimeter chassis showing plug- 
in arrangements. 
VELOCITY SIGNAL 
DEPTH] SIGNAL 
Figure 1 
267 
TRANSMITTED 
PULSE 
DEPTH AND ~ 
VELOCITY SIGNALS 
ae 
a 
INVERTED SOUNDER 
———<—= 
VELOCIMETER 
