. Basic methods for the calibration of sonar equipment. EQUIPMENT AT MOUNTAIN LAKES 125 0 IxlO'"*' 2x10"^ if.\0'^ 4) â¢<**, ⢠TRIAL 1 ⢠2 3 4 5 10 FREQUENCY IN KILOCYLES PER SECOND B Fici'RK 03. Tiansic'iil ^niahsis ol explosive u'a\c foiiii. curve, it ni;iy l)e assimutl tliai the phase ichitioii is fairly Huear. Tliis assiiiiiptiDii should be Itirilier in- vestigated. H()we\er, the jjhase irecjiiency character- istic does not affect tlie aniplitiide-frequency analysis of the transient but only affects its wave form. The frequency analysis of the transient is made from lire
. Basic methods for the calibration of sonar equipment. EQUIPMENT AT MOUNTAIN LAKES 125 0 IxlO'"*' 2x10"^ if.\0'^ 4) â¢<**, ⢠TRIAL 1 ⢠2 3 4 5 10 FREQUENCY IN KILOCYLES PER SECOND B Fici'RK 03. Tiansic'iil ^niahsis ol explosive u'a\c foiiii. curve, it ni;iy l)e assimutl tliai the phase ichitioii is fairly Huear. Tliis assiiiiiptiDii should be Itirilier in- vestigated. H()we\er, the jjhase irecjiiency character- istic does not affect tlie aniplitiide-frequency analysis of the transient but only affects its wave form. The frequency analysis of the transient is made from lire photographic record by the use of a liar- mouic analyzer. The USRL was fortunate in having tlie use of a Hcnrici Analyzer,'â ''^â ^" through the coop- eration of the Department of Physics, Case School of Applied Science. This analyzer gives the relative am- plitudes of thirty harmonics. A complete frequency analysis of a transient requires from several hours to severaf days, depending on the complexity of the transient. The resultant data are then only relative and require supplementary computations for conver- sion to actual units such as pressiue and frequency. A sample analysis of an explosive wave by this method is shown in Figure 63. The analysis gives the rms pres- sure in db vs I dyne per sq cm in a 1-c band as a func- tion of frequency. *â¢- '^ Auxiliary Laboratory Equipment Considerable auxiliary eiiiiipment is needed in the calibration and maintenance of the measuring sys- tems as well as in the calibration ol transdiiters. For convenieiue in description the apparatus is di\ided into six groups: resistance and impedance bridges, test meters, portable signal generators, cathode-ray oscilloscopes, wattmeters, and miscellaneous ccpiip- ment. Resistance and Impedance Measuring Bridges The laboratories are pro\ided with a number of ailmittance and imjJedance bridges suitable for meas- menients o\er a wide range ol \allies wiih the \arious lieqiiency ranges.
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