65 research outputs found
Long range sound transmission : interim report no. 1, March 1, 1944 - January 20, 1945
Experiments are described to demonstrate a new method of sonic signalling at extremely long ranges in the oceans, utilizing the natural sound channel. Signals were made by causing a four pound charge of TNT to explode at about 4000 feet depth. These signals have the following qualities:
(a) Extremely long range transmission (probably 10,000 miles).
(b) Signal is positively identifiable.
(c) Abrupt termination of the signal allows the arrival time to be read with an accuracy better than l/20th second. This permits location of source to better than a mile, if the signal is received at three suitably located stations.
(d) The signal duration is related in such a way to the distance that the distance may be estimated to 30 miles in 1000 from reception at a single station.
The limitations are:
(a) It is required that the great circle path which the sound follows between source and receiver lie entirely in deep water (probably at least 1000 fathoms).
(b) Sound travels in water at a speed of roughly 1 mile per second so that the interval between the origin of the signal and its reception becomes sufficiently great to be a handicap for some uses, particularly with aircraft.
The signals were received to distances up to 900 miles. Two receiving arrangements have been used, a hydrophone hung
4000 feet over the side of a ship which was hove to, and a shore connected. hydrophone which lay on bottom 4000 feet deep.
Extrapolation of the results indicate a range of at least 10,000 miles from this size charge. Recommendation is made to utilize a network of monitoring stations to locate planes, ships, and life rafts in distress on the open oceans. Three or more stations receiving a signal could locate the source better than one mile.Con tract NObs - 2083, Formerly OEM: sr - 3
Recommended from our members
Propagation of explosive sound in a liquid layer overlying a semi-infinite elastic solid
Structure of the western Somali Basin
Originally issued as Reference No. 67-38, series later renamed WHOI-. Reprint from Journal of Geophysical Research, vol. 72, no. 10, May 1967.The western Somali Basin in the northwestern Indian Ocean is covered by thick deposits
of terrigenous sediments. Seismic reflection profiles show, however, the northern and southern
parts to be very different. The northern sections is a deep basin filled with thick uniformly
stratified sediments. It is enclosed by the continental margin to the west and north,
Chain ridge to the east, and shallow basement structure to the south. A change in depth
of basement occurs along an approximately east-west line at latitude 3°30'N very near the
southern end of Chain ridge. In the southern portion of the basin the basement is shallow,
and, immediately south of latitude 3°30'N, it has high relief. Stratified flat-lying sediments
fill the basement depressions, and isolated hills formed of basement material rise above the
abyssal plain deposits. Farther to the south the abyssal plain becomes very narrow. Gabbro
dredged from the southeast slope of Chain ridge has been dated by the potassium-argon
method as 89.6 ± 4.5 m.y., which should be considered a minimum age. The evidence suggests
that the entire sediment sequence of the northern basin was deposited subsequent to
the formation of the ridge. The thin sediment cover of the southern portion of the basin is
probably no older than Tertiary.Office of Naval Research under contract
Nonr-4029(00) NR 260-101
Recommended from our members
Further study of atmospheric pressure fluctuations recorded on seismographs
Recommended from our members
Crustal structure and surface wave dispersion. Part II, Solomon Islands earthquakes of 29 July 1950
- …