increasing the sensitivity of the hydrophone and narrowing the bandwidth 

 of the receiver. The object of any improvement would be to keep the MDS 

 lower than the required source pressure level,, at the hydrophone. 



TEST PROGRAM AND PROCEDURES 



Initial testing of the Expendable Doppler Penetrometer was conducted 

 to demonstrate that the concept was workable and that accurate data 

 could be obtained and to discover if the velocity and penetration performance 

 of the device were as expected. To provide required data, tests were 

 attempted at four locations in the Santa Barbara Channel off the California 

 coast in about 100, 600, 1,200 and 70 feet of water. 



In all the tests, except one attempted in 1,200 feet of water, the 

 penetrometer was deployed with an intent to recover it. In 100 feet of 

 water this involved lowering a large loop of recovery line in the water 

 and releasing the penetrometer from the water's surface with the free 

 end of the recovery line attached to the rear of the penetrometer. In 

 600 feet of water, the penetrometer was rigged in a manner identical to 

 a gravity corer. In 70 feet of water it was released at the water's 

 surface and allowed to freefall to the seafloor with only a small cord 

 attached to it. After divers found the penetrometer by swimming down 

 the cord they attached a recovery line. In the test attempted in 1,200 

 feet of water the penetrometer was released at the water's surface with 

 no lines attached. 



In all the tests the CEL warping tug's UQN Sonar Sounding Set was 

 used in its passive listening mode to monitor the penetrometer. After 

 the datum signal was processed through a frequency modulated discrimina- 

 tor the DC-voltage analog of the velocity of the penetrometer was 

 recorded on both magnetic tape and paper for later data reduction. 



TEST RESULTS 



The first series of tests was conducted in 100 feet of water 2 

 miles south of Port Hueneme, California, from the CEL warping tug. The 

 loop-of-line technique was used to recover the penetrometer. Four tests 

 were conducted. Because the depth sounder-receiver was not working 

 correctly, the data gathered were not of good quality (see Figure 4). 

 However, it was possible to detect impact with the seafloor when the 

 penetrometer stopped and to estimate impact velocity. This was sufficient 

 to calculate penetrations. Penetrations measured from mudlines on the 

 penetrometer and penetrations calculated from the data compared reasonably 

 well and are shown in Table 1 . 



The second series of tests was attempted in 600 and 1,200 feet of 

 water about 5 miles south of Santa Barbara, California, from the CEL 

 warping tug. In 600 feet of water the penetrometer was lowered toward 

 the seafloor, rigged identical to a gravity corer. Two tests were 



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