. The Earth beneath the sea : History. Ocean bottom; Marine geophysics. SECT. 1] REFRACTION AND REFLECTION TECHNIQUES AND PROCEDURE 29 outputs of two of the hydrophones on the first arrivals, and high- and low- frequency outputs from one of the hydrophones on the water-borne arrivals. Information from the monitor records is used by the recording operator to check for instrument trouble or noise, and to decide on changes in charge size to be called to the shooting ship. A running plot of rough readings from the monitor records is maintained during the run for preliminary interpretation. Wheneve
. The Earth beneath the sea : History. Ocean bottom; Marine geophysics. SECT. 1] REFRACTION AND REFLECTION TECHNIQUES AND PROCEDURE 29 outputs of two of the hydrophones on the first arrivals, and high- and low- frequency outputs from one of the hydrophones on the water-borne arrivals. Information from the monitor records is used by the recording operator to check for instrument trouble or noise, and to decide on changes in charge size to be called to the shooting ship. A running plot of rough readings from the monitor records is maintained during the run for preliminary interpretation. Whenever a roll of recording paper has been run through the oscillograph, it is removed and developed to check on the quality of the photographic recording on all channels and to jjermit the beginning of data reduction aboard ship. The recording system used at SIO is completely transistorized except for the lOO Frequency ~ c/s 1000 Fig. 7. Response of SIO system from hydrophone output to oscillograph trace; dB relative to maximum response of each channel. Auxiliary information that must be noted includes all of the information listed for the shooting ship plus attenuator settings, depth at the receiving ship and a running record of instrument connections and settings. At the conclusion of each station, electrical calibrations are made on one more of the hydrophones by inserting a series of calibration signals (from 2 c/s to 20 kc/s) to the calibration resistor in the pre-amplifier and taking a brief record. This gives the total response of the system excluding the hydrophone element; an example of the response of the system from hydrophone output to oscillograph trace is given in Fig. 7. In the system of recording developed at Lamont and Woods Hole, most of the differences in procedure stem from the practice of silencing the ship during. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability -
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Keywords: ., bookcentury1900, bookcollectionbiodivers, booksubjectoceanbottom
