US2411910A - Signaling system - Google Patents

Description

Dec, 3, 194%. E; E. TURNER, JR 3 SIGNALING SYSTEM Filed May 13, 1940 2 Sheets-sheaf. 1

TUNED AMPLIFIER TUNED AMPLIFIER 4 INVENTOR.

na/1 E Turner \7i'.

Dec, 3, 1946. TURNER, JR 2,411,910

SIGNALING SYSTEM Filed May 13, 1940 2 Sheets-Sheet 2 Fig. 2

INVENI'OR.

Eda m". /arner I El /W W ATTORNEY.

Patented cc. 3, 1946 SIGNALING SYSTEM Edwin E. Turner, 31:, West Roxbury, Mass, as=

signor, by mesne assi Signal lilompany, Boston,

of Delaware garments, to Submarine Mass, a corporation Application May 13, 1940, Serial No. 334,774

4 (Claims.

The present invention relates to a sound ranging system and more particularly to one employing continuous waves and is particularly applicable to high frequencies of the order of :4000 to 5000 cycles per second and higher and may particularly be applied in or near the supersonic range for signaling and sound ranging in water or other heavy dense media.

The method of sound ranging presently employed in general does not permit rapid observation of foreign objects or obstacles in the vicinity' of the observing or listening vessel. Usually in this type of work a supersonic beam isemployed which sends out a ray of sound only in one direction and therefore makes it necessary for the observer to search each direction independently in some successive step-by-step manner. If, for instance, the range to be searched in water is 5000 yards, the echo from an object of this distance will take six seconds to return so that if this is the range which is being observed and if it is further assumed that the beam is approximately 15, for 21,360" sector one set of observations would take approximately 144 seconds or longer. It is highly desirable for many purposes to reduce this time if possible. More rapid observations of obstacles in the vicinity of the vessel are necessary not only for effective collision prevention with other moving vessels, but also for purposes of military observations such as the detection of submarines. mines or torpedoes.-

The criterion in the avoiding of collision between any two obstacles is the constancy of the direction of approach. If two vessels are always moving towards each other with the same angular direction between them, a collision is bound to occur. If, on the other hand, this angle is constantly changing, the vessels will not collide. The present system employs in general this principle and it may be applied either to intermittent or continuous observations by the use of direction determination by means of the principles of phase displacements in the fundamental signaling frequency.

Without further enumerating or describing the sity curve in a horizontal projection of the radiation of the transmitter shown in Fig. 4; Fig. 5A shows the horizontal projection of an intensity curve by a beam projector; Fig. 6 shows the intensity curve of the device'indicated in Fi 2 in a horizontal projection; Fig. 7 shows a top view of the element of Fig. 1 directly below it; Fig. 8 shows schematically the layout in'relation to a vessel of the system; and Fig. 9 shows a directional diagram for the receiver of Figs. 2 and 3.

In the system any type of transmitter may be employed which is cable of sending out the desired compressional wave with the intensity pattern either of Fig. 5 or 5A. If that of Fig. 5A is used, the beam must be rotated. In Fig. 4 the central unit l may be any high frequency transmitter as, for instance, a magnetostriction oscillator, a piezoelectric crystal quartz oscillator or a Rochelle salt or magnetic oscillator. The desired beam pattern of the oscillator l of Fig. 4 is indicated in Fig. 5 where the oscillator is not rotated. the curve 2 indicating the horizontal intensity curve with reference tov a vessel. It will be noted that this curve is referred to the keel-line of the vessel on which the apparatus is installed and is in the form of a cardioid with a blind spot or features and advantages of the present invention, the invention will be fully and completely described in the specification below in connection with the drawings illustrating an embodidirection between the lines OA and OB aft towards the stern of the vessel in which angle the receiver is installed. This intensity curve may be obtained either by the construction of the oscillator or transmitter itself or it may be produced by screening by means of the sound screen 3 which is so placed with respect to the transmitter 8 to prevent radiation in the aft portion of the ship. The whole structure of Fig. 4 may be installed in a well or sea-chest within the vessel and be projected below the keel of the vessel so that it will be free to transmit its compressional waves in all directions.

If desired, in the pre lent system the intensity or radiation pattern of Fig. 5 maybe varied ac cording to the direction in which listening is desired to be efiected. If desired, the casing surrounding the transmitter l including the shell 6 as well as the sound insulating means 3 may be fixed in a stationary position and the transmitter l, which may be given a form of a directive beam as above stated and as shown in Fig. 5A by the intensity curve 6, may be rotatable within the housing by means within the vessel. In this way the beam as shown by the curve 6 will be rotated around in the desired listening sector. The width of such beam may be made to have the desired angular opening as between the lines 0C and OD or as further illustrated in Fig. 8 between the lines I and I2 by proper design of the transmitter itself and the beam may be rotated at any slow speed of the order of one or two revolutions per second.

In the present system, therefore, the transmitter I may be either stationary or rotary and further may operate continuously or discontinuously as will be seen from the description below.

In the system as schematically shown in Fig. 8, the transmitter or projector I projects a beam or pencil of compressional waves within the angle formed by the lines II and I2. This projector l0 may be rotated by means of the shaft l3 through the drive l3 through the whole 360, as indicated by the circle I4, sending .continuously through the keying commutator l4 its beam except within the aft sector formed by the lines I5 and I6 when the circuit to the projector H3 is broken by the insulating segment IS in which sector the projector will be silent. The

purpose of this is to acoustically shield the receiver H which, of course, may also be shielded by acoustic insulation I8 positioned within the housing IS in which the projector l0 rotates. In this way the direct signal will not be picked up by the receiving unit I]. The receiving unit I? is indicated in Figs. 2 and 3 and comprises a suitable housing supporting two directional receiving units 2| and 22, respectively, each of which has a horizontal intensity pattern for recept on in the shape of a figure eight a indicated in Fig. 6.

The unit shown in Figs. 2 and 3 must be directional in the present system from the point of view of the phase relationship with respect to the compressional wave. The unit 2| of Fig. 2 is composed of a group of thin laminations of magnetostrictive material. These laminations are in the shape of a grill with a great number of parallel stems or bars 3|, 3|, each terminating in end plates 32. 33. These laminations are all held together either by means of the coil wh ch is shown as alternately threading in and out between successive bars or by means of the pins 34, 34 holding the laminations together in the edge plates or surfaces 32, 33. In place of making the coil 35 in the form of a single winding threading alternately back and forth between successive bars,-individual coils for each of the bars 3| may be used. The whole block of laminations when assembled together is supported in their mid section by means of the inverted V-shaped projection 36 which is formed by the inverted V-shaped projection at the end of each of the laminations and which, therefore,

form a wedge when the laminations are assembled in the block, which wedge is supported by the brackets 31 and 38 Which extend from the casing 2|] of the unit.

The unit 22 is similar to 2| except that it is posit oned in a direction normal to the unit 2| and therefore the V-shaped support of this unit in the bracket 38 must run normal to the V-shaped support for the wedge 36. The units 2| and 22 operate at a frequency to which tnsystem is resonant.

The laminations are designed so that the stems 3| with their end masses provided by means of the side plates 32 and 33 operate a8 a one-half wave length system with the stems 3| substantially narrow as compared with the width and length of the elements 32 and 33 the masses of which are proportionately effectively carried by the stems 3| making up the half wave length oscillating element. In this way the stems 3| act loads of the elements 32 similarly as a loaded rod with equal loads at each end of the stem. The resonance of the system should be a one-half wave length resonance with no substantial mass in the stem 3| itself so that practically the stem acts as a pure elastic member.

The system further must be so loaded by the and 33 that the distance between the outer edges S and S is nearly or exactly one-half wave length in the medium in which the unit is to act as a receiver or transmitter since it may so be used. It will be noted. therefore, that, for instance, in the water medium the magnetostriction elements must be loaded to compensate for the difference in velocities of sound in nickel and in water. Inasmuch as the velocity of sound in nickel is about three times as high as that in water, the system must be loaded to bring the normal one-half wave length of nickel. in a uniform rod by means of loading to the corresponding one-half wave length in water.

With the design of the described the unitof Figs. 2 in the shape indicated in Fig. 6. This is illustrated in Fig. 9. If sound is approaching from the NS direction and the unit 2| is one-half wave length long as referred to the medium, the energy picked up by each face will be moving in opposite directions with the result that there is a maximum of co'mpressionor expansion in the stems 3| of the unit 2|. Therefore, for sound approaching in the horizontal longitudinal direction of the unit, the unit 2| will pick up maximum sound energy. However, in the position which the unit 22 has in relation to this sound wave. the whole unit will be acted upon similarly with the result that no motion of the unit will take place. Therefore for sound approaching normal or transverse to the unit 22, as for instance, from the NS direction, no sound energy will be picked up. Consideration of the explanation in relation to Fig. 9 will show that in Fig. 6 the figure-eight curve composed of the curves 25 and 26 belong to the unit 22 while the curves 23 and 24 belong to the unit 2|. Considering the radiating faces small as compared to the wave length, it may be shown that the intensity pattern is expressed by the equation 7T T=Slll cos D) where spacing between radiating faces is onehalf wave length. In the equation, r is the polar vector and D the polar angle, both taken from the origin.

The unit above described directly ties in to a cathode ray tube or a tube of a similar nature to indicate directly the directionof the source of an approaching sound wave. In this case each unit 2| and 22 has its energy impressed upon separate tuned amplifiers 40 and 4|, respectively, the outputs of which each operate respectively a pair of plates 42, 43 and 44, 45 of a cathode ray tube 46. As the oscillations picked up by the units 2| and 22 are harmonic in character, a cathode ray tube would produce straight line indication for two circular figure-eight patterns. While the patterns in Fig. 6 are not circles, nevertheless even without compensation they are substantially near to the shape of circles so that a clear indication can be obtained. Compensation maybe introduced to flatten down the paterns of Fig. 6 to even more circular form if necessary. This may be done by making the output of the amplifiers system as previously and 3 will be directive pure harmonics, or by the addition of magnetic field control on the electron beam, or in any wellknown manner. An indication as a line 6'', as shown in Fig. '7, may be referred 0n the face of the tube 46 to a scale 48 so that the angular direction of the source may be determined. In order to eliminate the double directional effect particularly in the aft direction if desired, a sound screen or acoustic insulating means may be used directly aft in the casing 20 of the receiver as illustrated by the sound screen or insulation 50.

In the present system it will be noted that the receiver is active simultaneously in all directions. With this system, therefore, a signal could be sent out in all directions, if desired, or a beam could be rotated in the desired listening range, for instance, 180 from starboard through forward to port on a vessel. If such rotation took place in one-half second, a complete sound ranging of the entire sector for a distance of 5000 yards would take place in six seconds.

The units 2! and 22 are preferably elongated vertically and may in this dimension be a number of wave lengths so that a large amount of energy can be picked up and noise other than from a horizontal direction may be eliminated. This result will follow, since a long vertically placed receiver is horizontally directive. The thickness of the laminated stack must, however, be small as compared to the wave length in the compressional medium of the compressional energy to be received to establish the desired pattern as set forth in Fig. 6.

Having now described my invention, I claim:

1. In a submarine signaling system, a, pickup unit composed of two resonantly tuned magnetostrictive units each having sound pickup surfaces parallel to one another and spaced at perpendicular distances in line one-half wave length apart as measured in the medium of the sound to be picked up in the medium, each of said units having said surfaces arranged at right angles to the other.

2. In a submarine signaling system, a pickup device composed of two tuned mag'netostrictive' units, each having sound pickup surfaces spaced one-half wave length as measured in the sound medium of the resonant frequency.

4. In a submarine signaling system, a sound pickup unitcomprising a block of magnetostrictlve laminations of a grill type forming a plurality of narrow parallel bars all joined together at their ends forming a sound radiating face, said parallel bars and the end elements being, onehalf wave length system for the signaling frequency, said end elements comprising a mass load whereby the distance between the sound radiating faces is one-half wave length as measured in the sound medium and coil means surrounding said bars for converting the magnetostriction energy to electrical energy and vice versa.

EDWIN E. TURNER, JR.

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