B. "SMITH- CUMMINGS-MEICHNER APPARATUS" 



1. Model: No model number; designed by W. O. Smith, 



G. B. Cummings, and F. Meichner 



2. Manufacturer: Target Rock Corp., Hempstead, N. Y.; 



Telephonies Corp., Huntington, N. Y. 



3. Approximate cost new: $15,000 to $18,000 (March 1959) 



4. Maximum water depth in which operative: 



Empirically determined: 100 feet 

 Estimated: 250 feet 



5. Maximum penetration of sediment: 



Empirically determined: 800 feet (with transducer placed 

 on the bottom; 200 to 300 feet (with transducer at the 

 surface) 



Estimated: 1,500 feet 



6. Transducers: 



Type: Transducer-receiver: ammonium dihydrogen 

 phosphate (ADP) crystals 



Location: Outboard, fixed to side of ship. (A later model 

 uses transducers mounted on a sled that is towed along 

 the bottom: W. O. Smith, personal communication.) 



7. Acoustic power: 250 to 2,500 watts 



8. Acoustic frequency: 



Approximate range: Apparatus is designed for operation 



only at certain peak frequencies. 

 Peak: 6, 11.5, and 16 kilocycles. (The transducer has a 



natural resonance of 1 1 kilocycles. At 6 kilocycles, the 



output power is 10 db below that of the normal 11-kilo- 



cycle operation.) 



9. Acoustic pulse length: 1, 2, 3, 5, 7, or 9 milliseconds 



10. Acoustic pulse repetition rate: 250 pulses per second 



11. Receiver band pass filter network: None 



D-3 



