70 



USRL TEST STATIONS 



Figure 4. General view of test area of Pier 1. Several suspension carriages and the rotator are visible. Apparatus in 

 foreground is being used to make impedance measurements. 



are of interest in connection with underwater sound 

 gear used on submarines. 



One of the two outdoor piers is equipped for 

 handling devices, weighing as much as 2,000 pounds, 

 by chain hoists travelling on an overhead rail be- 

 tween the loading platform and the far end of the 

 pier. The second pier is equipped for devices of not 

 more than 250 pounds. For testing distances greater 

 than those provided by the piers, a raft with a work- 

 ing load capacity of 3,000 pounds is available. Signal 

 transmission and power cables extending from the 

 laboratory to a position 250 yards out in the lake pro- 

 vide facilities for operating equipment on this raft. 



The laboratory has its own machine shop, water 

 supply, and heating system. Compressed air and elec- 

 tric power are available throughout the building. 

 Auxiliary equipment includes meters for measuring 

 current, voltage, or power; impedance bridges; vac- 



uum-tube test sets; cathode-ray oscilloscopes for 

 observing wave shapes; and filters for limiting fre- 

 quency bands. 



The electric energy is supplied at 230 volts, 60 

 cycles, with the midpoint grounded. This voltage is 

 used on the larger motors. The 115-volt supply is 

 regulated to keep a uniform voltage on the signal 

 generators, amplifiers, detectors, and recorders. 



All high-voltage requirements are supplied by 

 regulated rectifiers associated with the various system 

 components. Thus, drifts in the calibrating apparatus 

 resulting from variation in the supply voltage are 

 held at a minimum. A 24-volt d-c supply for the opera- 

 tion of relays and indicator lamps is obtained from 

 rectifiers energized by the 1 15-volt line. 



Most of the electrical equipment was designed and 

 constructed by the Bell Telephone Laboratories 

 under contract with the National Defense Research 



