h. Transparency and visibility (scattering and attenuation) 



i . Current speed 



j . Current direction 



k. Wave height 



1 . Wave period 



m. Wave direction 



n. Bottom structure (corers, grab samples, camera, television) 



o. Ice (thickness, temperature, hardness, etc.) 



6. Other Geophysical Factors 



a. Gravity 



b. Geomagnetism 



STAGES TO BE CONSIDERED 



1. Sensing 



2. Packaging (waterproofing, streaming, miniaturizing, etc.) 



3. Transmitting (cables, winches, relays, amplifiers, oscillators, etc.) 



4. Converting, recording, and storing 



SYSTEMS CONCEPTS 



In first considering oceanographic measuring systems, one is 

 immediately impressed by the large number of combinations of 

 components possible. However, upon further examination, it becomes 

 apparent that these are but variations of a few basic concepts. 



First, instruments can be classified as those measuring some physical 

 or chemical property jji situ , and those used in collecting samples for 

 laboratory testing and analysis. Consideration of the second group will 

 be deferred. Measurements in situ can be made by instruments with 

 self-contained recording devices or by instruments that telemeter the 

 record to a ship, airplane, buoy, or land station. Telemetering instru- 

 ments are of first interest. 



Telemetered signals from instruments used in oceanographic meas- 

 urements are at present variations of one of the following: 



1. Amplitude modulated signals 



2. Frequency modulated signals 



A- 4 



