DESCRIPTION OF ORLANDO TEST STATION 



133 



Figure 75. Arrangement of electrical equipment in the 

 Orlando laboratory. 



Figure 76. View of the Orlando barge. 1 lie barge is 

 equipped with hoist arms at each end and a boom crane 

 for handling equipment. 



Figure 75 is part of the power amplifier system tie- 

 scribed above. It is capable of delivering 1,500 watts 

 of electric power at frequencies from 2 to 100 kc. 

 Facilities are available for the interconnection with 

 other parts of the electric system and for measuring 

 and accurately controlling the power levels. A watt- 

 meter of the type developed by USRL is used with 

 this unit and a motor generator set furnishes the 440- 

 volt 3-phase power required. 



Barge System 



A general view of the barge is shown in Figure 76. 

 The floor and frame are supported by 88 barrels, 

 which are grouped uniformly under the floor and sec- 

 tionalized so that individual units can be removed 

 for repair or replacement without seriously interfer- 

 ing with the buoyancy of the barge. A pontoon is in- 

 stalled on the side where the house containing the 

 electric equipment is located to provide the addi- 

 tional buoyancy necessitated by the uneven weight 

 distribution. The barge is positioned by means of 

 cables at the four corners attached to mushroom 

 anchors imbedded in the lake bottom. Additional 

 anchors of a screw type are connected by cables to 

 winches which may be adjusted to level the barge 

 and lower it in the water for greater stability. 



Equipment is transported from shore in a flat-bot- 

 tom boat of 1-ton capacity and raised onto the barge 

 with a swivel crane. 



The test basin is about 45 feet long and is fitted 

 with steel rails which are spaced the same as at other 

 USRL. basins, to make possible the interchange of 

 carriages between them. An overhead rail is used only 

 in the center while wooden hoist arms, visible in Fig- 

 ure 7(>, are provided at each end of the test area. The 

 hoists are lighter than a full length rail and are better 

 adapted to handle the long rods that are used on the 

 barge to take full advantage of the greater water 

 depth. If the surface and bottom are total reflectors, 

 the optimum testing depth is one-half the total depth 

 but, if the bottom is absorptive, deeper testing would 

 be advantageous. Actually, the tests are made at 

 about one-half the water depth of 33 feet. Figure 77 

 shows a line hydrophone being mounted on a rod for 

 testing at this depth. Hydrophones can be suspended 

 either horizontally or vertically and operated with 

 a synchro-controlled rotator similar to the one on the 

 pier. 



The building on the barge contains a complete 

 electric testing system, including those facilities 

 which are usually installed in the transmitting and 

 receiving booths on the piers. The booths are not 

 required here because of the short distance to the 

 basin. Hie sending system is essentially the same as 

 the one on the piers, but the detector is omitted from 

 the receiving system so that the amplifier recorder is 

 responsive to any signal within the frequency band 

 of the system 200 c to 150 kc. This makes the system 



