US1501105A - Submarine signaling - Google Patents

Description

Jufiy 15 M24. 1,501,105

R. A. FESSENDEN SUBMARINE S I GNALI NG Filed March 23, 1918 577477 TEMP/1; 9/1/5 Patented July 15, 1924.

BUBMABINE SIGNG.

Application filed March 28, 1918. Serial No. 224,288.

To all wiwm it may concern:

Be it known that I, REGINALD A. F ESSEN- DEN, of Brookline, in the county of Norfolk and State of Massachusetts, a citizen of the '5 United States, have invented new and use- Improvements in Submarine Signaling, of which the following is the specification.

My invention relates to the generation and j utilization of elastic impulses and more particularly to submarine signaling, and still more particularly to the detectlon of submarines.

The figure forming a part of this specification, shows partly diagrammatically, 16 means adapted for carrying out my 1n-' vention.

My invention has for its object the increased efliciency zation'of elastic im ulses and in submarine 2o signaling and in t e detection rines, and other similar bodies.

Referring to the figure, 11 is a tank containing fluid, for example a fuel oil tank or a water tank, preferably extendin' the full as. width of the vessel 23 and prefera 1y intermediate between the bow of the vessel and the stern of the vessel, as the separation from the bow tends to reduce the water noise and the separation from the stern tends to 80 reduce the machinery noises, and especially if there are other compartmehts, such as'12.

and 13, inserted between the tank 11 and the bow of the vessel and between the tank 11 and the machinery compartment of the vessel, as these compartments 12 and 13 act as sound screens.

An additional advantage of having the tank in this intermediate location and also extending from one side to the other of the vessel, is that on account of the bending of the sound waves, signals can be sent and heard and submarines detected ahead or astern substantially'equally as well, or better than abeam.

The tank 11 need not be a single tank but may be divided up into a num er of compartments, for example by the horizontal bulkhead 14. This horizontal bulkhead l is preferably several feet below'the water line of the vessel and is preferably sound proof, as it has been found thatby this construction water noises are very largely kept in the generation and utiliof submaaway from thereceiving apparatus, which lower-part of 1 is preferably located in the the tank 11, i. e. between the horizontal bulkhead 14 and the'bilge ofthe vessel.

When it is desired to use the fuel oil from one portion of the tank 11, for example from the upper portion, this 011 may be pumped into a second tank 15 and used from thence the upper portion of the tank 11 being filled with sea water. In this way the tank 11 may be kept full all the time and the noise of the swashing around of oil minimized.

en it is desired totake in more oil, the sea water is pumped out .andthe tanks steamed in'the usual way, the steam in this case removing the last traces of the salt Water, just-as in ordinary practice it is used to remove the last traces of oil. Ur, if desired, the upper portion of the tank may be left empty.

16 is a cross shaped sound screen and 17, 18, 19, 20 are signaling apparatus placed one in each angleof the cross shaped sound screen.

These signaling ap aratus are preferably such as are suitable f ing or condenser transmitters and receivers of the type herein described. I

Apphcant has discovered that electric capacities or condensers are very efficient transmitters and receivers of compressional waves in liquids. Such capacities maybe of the usualball or plate form, bat are preferably made up of metallic films alternately connected toge separated by a dielectric.

The dielectric is preferably elastic and homogeneous and may be made of india rubber, glass, mica, -or'paper saturated with paraffine or oil. In fact, any good insulatmg material may be used.

In the figure, 17 ai1d18 represent, diagrammatically, condensers "having a solid dielectric .of mica or glass and. 19 and 20 represent condensers having a dielectric composed of paper saturated with/oil or oil without paper, and enclosed in boxes 21, 22 to prevent the fluid dielectric from mixin with the oil in the tank 11 Vhen an alternatin voltage is impressed on these condensers, r exampleby'means er and or sending and receivplates or j of the alternating current generator 25 and keys 26, 27, the electrostatic attraction between the metallic plates or films of the condensers 19 and 20 compresses the dielectric between the plates and a compressional wave travels out, being transmitted from the condensers to the fluid surrounding the condensers, which in the case shown is the oil in the tank 11, and thence to the water surrounding the vessel.

A source of continuous current voltage, as shown in 24, ispreferably placed in series with the sourm of alternating current voltage to increase the strength of the signals.

In this way compressional waves may be emitted from either or both of the condensers 19 and 20 and-may be transmitted out in the direction the quadrant of the sound screen 16 faces, in which the condenser is placed.

The frequency of the compressional waves emitted will depend upon the frequency of the alternating voltage source 25. The compressional waves are preferably either ordinary sound waves of a frequency of about 500 to 1000, or for other work preferably anacysms, i. e. compressional waves above the limit of audibility. The use of a technical term to express the concept of dilatational waves in material media and of a frequency above thatof audibility has been felt for some time,.and a number of terms have been prop The term anacysms is preferred, as it has priority, having been used by applicant in a report to the U. S. Navy, Dec. 21st, 1912; and it is good Greek, having been used by Aristotle; while supersonics has been derided by classicalscholars as meaning something quite diiferent, i. e. something sounding above other noises, as a trumpetin battle. I have found that anacycms havin' a frequency as high as 40,000 are suitable, ut frequencies as high as 100,-

000 or even 200,000 per second may be used.

Receiving on a condenser submarine'signaling apparatus ma be accomplished in a number of ways. or example, the, condensers 17 and 18 may be charged by the source of continuous voltage 28 and connected to the head phones 29, 30. Sound waves-originating from a source ahead of the vessel, on strikin the condensers 17 and 18 alter the capacity of the condensers and hence alter the charges on the condensers and. hence produce an alternating current in the circuit ers and the head a sound in the head phones. If the sound source is located off the port bow of. the vessel the intensity of the sound waves received by the condenser 17 will be greater than that received b the condenser 18 and hence the change 0 capacity in the condenser 1'7 and the sound produced in the head phone 29 wil1 be greater than that f 27 are signaling keys kept received by the condensers compounds, in the well known containing the condens- "g phones and hence produce 4 ducing well known forms,

the condenser 18 and head phone 30. In this way it is possible to tell with sufiicient accuracy for most purposes the direction of the sound source, and if it is desire to know the direction exactly the vessel may be caused to turn to port until the sound comes in with equal strength on the-head phones 29 and 30 and when this is the case the vessel will be pointing directly to the source of sound.

In place of receiving in the manner above described, applicams heterodyne method may be used and this is especially useful when anacysms are used-for signaling.

A suitable arrangement is shown in connection with the condensers 19 and 20, where 25 is a ource of alternating current having 40,000 a second; 26 and a frequency of about closed for receiving; 24, 24 are sources of D. C. volta e, which are preferably used as givin lou er signals but which may be omitte if deslred. 31, 32 are. primaries of a transformer arranged to act oppos'tely to each other on the secondary 33, whereby the direction of the sound is more easily determined by noticing which is the stronger.

When no compressional waves are being 19 and 20, the currents. flowing into the condensers create, by means of the primaries 31 and 32, equal and opposite voltages on the secondary 33 and hence do. not cause any current to flow throughthe circuit containing the secondary 33 and the static telephone 34.

35 is a source of alternating current voltage of approximately a frequency of 39,000 a second and this is connected to the terminals of the static telephone 34 and to the secondary 33, as shown, but does not produce any-sound in the. static telephone 34 so long as no compressional waves are being received by the condenser 19 and 20, because this frequency of 39,000 is above audibility.

But on compressional wavesarriving from the port quarter and striking the condenser 19, the capacity of the condenser 19 is caused to vary and the voltages impressed by the primaries 31, 32 no longer balance each other and a current of the frequency generated by the generator 25, flows through the circuit 33, 34 and this method, with the current. generated bythe enerator 35, i. e. 39,000 per second, so as frequency. of 1,000 per second in the static telephone 34, thus proan audible signal.

-The. heterodyne .me'hod-of receivin in the form above described or in any 0 the is especially well adapted for receiving, because it eliminates disturb ing noises, especially theseare ofcomparatively low frequency.

i. e. 40,000 per second,

heterodyne water noises, since It is preferred when frequencies above 40,000 are used to have the oscillator tube described in Letters Patent No. 1,167,366 shortened, or else to work on a frequency that is a multiple of the quotient of the mitter, the apparatus will be extremely in- .eflicient unless the dielectric is of the same order of density as the liquid in which the condenser is immersed. For though air is a good insulator, if the condenser 19 is constructed with an air dielectric the efliciency as a receiver or transmitter will be only of the order of one per cent or less than if the dielectric has a den- I sity of the order of unity.

For a similar reason it is advisable that the elasticity of the dielectric should be of the same order as that of the liquid in which the condenser is immersed.

When detecting submarines or similar bodies by echoes, the second high frequency generator 35 is not necessary as the frequency. of the enerator 25 ma caused to vary regular y between the limits of say 35,000 to 40,000, and hence signals sent out when the frequency is say 36,000 w1ll be received back after reflection from the echo producing body on the condenser receivers at the instant when the generator 25 is generating a frequenc of say 38,000, and hence beats will be p uced having a frequency of 2,000 per second.

In this way the distance of the echo producing. body may be determined, by the number of beats produced; since the greater the distance apart the greater the di erence in frequency of reflected and generated oscillations.

In ex lanation of the increased efiiciency obtain the condenser plates constituted of substances having the same order of density,

and also preferabl of elasticity, as the flmd in which, the con ensers are immersed, for examplesea water, the complete theory has not been worked out, but it is probably due to the fact that when this is the case, and especially when the elasticity and density have such values that there is no difference in phase angle on passing from the fluid to the condenser, the compressional waves are transmitted completely and produce their full effect in varying the capacity of the condenser. While on the other hand, if the densit of the dielectric is of a different order 0 magnitude from that of the oil or sea water the compressional waves are only partly transmitted, being reflected at each ayer'of the-condenser and on nenetratexample,

-'by having the dielectric between ing a small distance and alsb the phase ofv the compressional wave ma be quite different in different parts of til that one part may be in compression while another part is in expansion whereby these two parts of the condenser will neutralize teach others effect in producing an indica- From examination of the following list of materials and densities,

Metals 0.53 to 22.4 Rll'bbel 1.2 Glass -l -3.0 Mica 3.0 Paraflined paper 1.5 Sea water 1.03 Paraflin oil 0.9 Air 0.0013

it will be seen that the densities of the ma terials on the left, which include all the standard non-gaseous dielectrics, and the metals which might be used for the conducting sheets of the condensers, are of an en-. tirely diflerent order of magnitude from the density on the right, i. e. that of air.

Consequently any standard commercial condenser made of the materials of the left hand column and used-while immersed in sea water or oil will'bea condenser which has its dielectric and metallic armatnres of the same order of density as the medium in which it is operating. While if it has an air or gaseous dielectric, or is used in air or a gas, it will not.

Heretofore condenser signal apparatus for producing and receiving sounds has always been of the latter class, i. c. has either had' a dielectric of air or gas, or has been used in a aseous medium. It has consequentlyhat? an extremely low efficiency, for reasons pointed out above in the specification.

Applicants discovery and invention is that condensers of the first class, i. e. con-' structed of materials such, as those in the i left hand column, and most of which are standard commercial articles, may be made very highly efficient producers and receiv-.

of magnitude as regards density as the con densers .the'mselves. In practice the increase pf efficiency -has 'been experimentally found to be in some cases more than 100 times, and to com-pare favourably with the hitherto generally used microphones.

What I claim is 1. In the art of' submarine signaling, means for producing and for detecting compressional waves in water, comprising a condenser having its dielectric and armatures of materials having their densities of e condenser so the same order of magnitude as Water; and

said condenser being-in operative relation to said water; 2. In the art of submarine signaling,

5 means adapted for the produetionandthe reception of compressional waves in ater, compr sing a condenser having its dlelecarmatures of metal; said condenser 10- immersed in and in operative relation to se w'ater.

RE INALD A, FEssENDE-N.

Images