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Publication numberUS3311868 A
Publication typeGrant
Publication dateMar 28, 1967
Filing dateJul 13, 1964
Priority dateJul 13, 1964
Publication numberUS 3311868 A, US 3311868A, US-A-3311868, US3311868 A, US3311868A
InventorsCupp Frederick B, Palley Carl W
Original AssigneeCupp Frederick B, Palley Carl W
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Sonic simulator
US 3311868 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

F. B. CUPP ETAL March 28, 1967 SONIC S IMULATOR 2 sheets-sheet 1 Filed July 15, 1964 )'7. ,dm d

AT YS.

F. B. CUPP ETAL March 284, 1967 SONIC SIMULATOR 2 Sheets-Sheet 2 Filed July 13, 1964 United States Patent O 3,311,868 SONIC SliMULATOR Frederick B. Cupp, Willoughby, and Carl W. Paliey,

Mentor, Ohio, assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed .luly 13, 1964, Ser. No. 332,696 24 Claims. (Cl. 340-5) The present invention relates generally to acoustical simulators and in particular is an improved method and means for simulating the screw noise, hull noise, rnachinery noise, land cavitation sounds produced by a running submarine boat.

Ordinarily, the cavitation sounds produced by an operating submarine act more or less as the basic or background sounds thereof and these sounds are essentially white noise, comprising random frequency and amplitude energy that does not have any clear, predominant frequency components or characteristics. This basic noise, of course, is modulated by the sounds of the submarines rotating screws and internal machinery. Consequently, in order to produce a reasonable replica of the sounds generated by a running submarine, these three factors must be effected and broadcast throughout the aqueous medium where a submarine boat is intended to be simulated. Usually, such simulators are incorporated in sonar beacons, decoys, and the like, but obviously they may also be employed in any desired surface or submarine vessels as necessary to optimize tactical combat warfare maneuvers.

In the past, several prior art sonic simulators have been used for similar purposes, and for many practical purposes, have been eminently satisfactory. However, in some instances, they leave something to be desired because they are relatively inefficient, lack fidelity, are large in size and weigh a great deal, and are difficult and expensive to manufacture and maintain, Ias well as requiring large, high-power, power supplies.

The instant invention overcomes most of the aforementioned disadvantages, in that, being transistorized, it is light weight and compact, and, in addition, has sluiiiciently high fidelity to be eminently satisfactory for most practical purposes.

It is, therefore, an object of this invention to provide an improved acoustical simulator.

Another object of this invention is to provide an irnproved method and means for simulating the sounds emanating from a running submarine boat.

Still another object of this invention is to provide a sonic simulator having a plurality of acoustical characteristics which may be respectively adjusted to provide a more realistic sonic picture under given operating conditions.

A further object of this invention is to provide a more reliable sonic simulator.

Still another object of this invention is to provide a sonic simulator that is relatively stabilized as a result of thermal compensation and heat sinks.

Another object of this invention is to provide a sonic simulator that is capable of being constructed as a printed circuit panel.

Still another object of this invention is to provide an acoustical simulator that is easily and economic-ally manufactured, maintained, and operated.

Other objects and many of the attendant advantages will be readily appreciated as the subject invention becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

rice

FIG. 1 is a block diagram of a representative embodiment of the subject invention; and

FIG. 2 is a detailed schematic circuit diagram of a preferred embodiment of the subject invention,

Referring now to FIG. 1, the preferred embodiment of the general concept of this invention is shown as having a noise generator 11 with the output thereof transformer coupled by means of -a transformer 12 to an arnplifier 13. Another transformer 14 is coupled to the output of amplifier 13, and a mixer amplifier 15 is corinected to the output of transformer 14. Due to the pan ticular component arrangement of transformer 14 and mixer amplifier 15, and the fact that another input is applied thereto from an integrator 16, said transformer 14-mixer amplifier 15 combination constitutes a mixer network 17 that will be explained subsequently in conjunction with the discussion of the invention embodiment of FIG. 2.

A high frequency multi-Vibrator 18 has its substantially symmetrical square wave output coupled to -the input of an integrator 19, the output of which is connected to one of the inputs of a control mixer 21. Likewise, a low frequency multi-vibrator 22 has its predetermined asymrnetrical rectangular wave output applied to the input of an integrator 23, the output of which is coupled to another of the inputs of the aforesaid control mixer 21. The output of control mixer 21 is, of course, coupled to the input of the aforementioned integrator 16. In the arrangement illustrated, the aforesaid high and low frequency multivibrators and their respective integrators constitute generators which produce sonic simulations of submarine internal machinery, gear whine, and screw noise, along with cavitation sounds produced by noise generator 11. Control mixer 21 enables sufiicient signal intermodulation to be effected, which, in turn, may, for example, result in an irregular pulsating signal with a beat that closely resembles the noise of a twin-screw submarine boat,

This signal, which emanates from the output of mixer amplier 15, is coupled to the input of a push-pull driver amplifier 24. A combination phase inverter and coupling transformer circuit 25 is connected to the output of driver amplifier 24 and the output thereof is coupled through Ia power transformer 26 to the input of an electroacoustical transducer 27. Transducer 27, of course, is the typical electroacoustical transducer that converts electrical energy into proportional acoustical energy and broadcasts it throughout a predetermined volume of a subaqueous medium, such as sea water or the like.

Referring now to FIG. 2, there is shown a B-lvoltage 31 and a ground 32 with a capacitor 33 connected therebetween. A transformer 34, having a primary winding 35 and secondary winding 36 has its primary winding connected in series with a noise generating, semiconductor diode 37 that has a high back resistance which is subject to small random variations, and these elements are, in turn, connected across the aforesaid voltage and ground. One terminal of secondary winding 36 is connected through a resistor 38 to ground, and a capacitor 39 is parallel connected with said resistor 38. From the junction of resistor 38 and capacitor 39, a thermistor 41 is connected to the aforesaid B-lvoltage. Another resistor 42 is connected in the B+ line between one terminal of the aforesaid primary winding of transformer 34 and the B-ljunction of a temperature compensation thermistor 41. The other terminal of secondary winding 36 of transformer 34, which, of course, constitutes the output of said transformer, is electrically connected to the base of a PNP transistor 43. The emitter of transistor 43 is coupled to the B-lvoltage and the collector thereof is coupled through a primary winding 44 of a transformer 45 to ground. A secondary wniding 46 of transformer 45 has one of the terminals thereof connected through a Capacitor 47 to ground, and the other terminal thereof is coupled to the base of another PNP transistor 4S, the emitter of which is coupled to the aforesaid B+ voltage. The collector of transistor 48 is coupled through the resistance portion of a gain-control potentiometer 49 to ground. A pair of capacitors 51 and 52 are connected between the aforesaid voltage and ground for voltage stabilization purposes and a resistor 53 is connected in said B+ line for voltage dropping purposes. The movable arm of the aforesaid potentiometer 49 is coupled through a capacitor 54 to the base of another PNP transistor 55. The emitter thereof is likewise coupled to the aforesaid B+ voltage and the collector thereof is connected through a primary winding 56 of another transformer 57 to ground. A secondary winding 5S of transformer 57 has its output terminals connected to the bases of a pair of PNP transistors 59 and 61, respectively. The center tap thereof is connected to a 24 volt direct current voltage and also through a resistor 62 to B+. Each of the collectors of transistors 59 and 61 are coupled to their respective input terminals of a primary winding 62 of another transformer 63. The emitters of transistors ,59 and 61 are interconnected and then connected to the aforesaid 24 volt direct current voltage. A secondary winding 64 of transformer 63 is coupled to one of the inputs of a transducer 65 with the other input thereto connected to the aforesaid 24 volt direct current voltage. As previously mentioned in conjunction with the explanation of the device of FIG. 1, transducer 65 is an electroacoustical transducer which converts the electrical energy supplied thereto into substantially proportional acoustical energy and, of course, this acoustical energy is intended in this case to be broadcast throughout a predetermined volume of a subaqueous medium, such as sea water or the like.

For temperature compensation purposes, another thermistor 66 is connected between the base of the aforesaid transistor 55 and B+ voltage. In addition, a biasing resistor 67 is also coupled between the base of transistor 55 and ground. Moreover, in order to insure better temperature compensation, a cooling system is incorporated in the device constituting this invention. This cooling system comprises a motor driven blower 68 connected in series with an inductance 69 and these elements are then effectively connected between the aforesaid 24 volt direct voltage and ground. For voltage stabilization purposes, a capacitor 71 is connected in parallel with the aforesaid series connected motor driven blower 68 and inductor 69.

Connected between the aforesaid B+ voltage and ground is a resistance network consisting of a resistor 72 connected in series with a potentiometer 73. The movable arm of said potentiometer 73 is connected to an astable multi-vibrator circuit 74, said astable multi-vibrator circuit consisting of a PNP transistor 75 which has the emitter thereof connected to B+ and the collector thereof connected through a resistor 76 toground. The base thereof is connected through a pair of series connected resistors 77 and 78 to the base of another PNP transistor 79. The emitter of transistor 79 is connected to B+ and the collector thereof is connected through another resistor 81 to ground. Of course, as can be readily seen, the aforementioned movable arm of potentiometer 73 is coupled to the junction of the series connected resistors 77 and 78. A coupling capacitor 82 is connected between the base of transistor 75 and the collector of transistor 79, and a coupling capacitor S3 is connected between the collector of transistor 75 and the base of transistor 79.

The output of multivibrator 74 is taken from the collector of transistor 79 and supplied to an integrator 84 consisting of a resistor 85 and a capacitor 86 connected in series therewith and to ground.

Connected across B+ and ground is still another voltage divider network consisting of a resistor 87 and a potentiometer 88 series connected therewith. Connected in parallel with said series connected resistor 37 and potentiometer 88 is a voltage stabilization capacitor 89. Also connected across said said B+ voltage and ground is a low-frequency astable multivibrator circuit 91, the circuitry of which is preferably designed to produce a predetermined asymmetrical rectangular waveform output signal. Included therein is a PNP transistor 92, with the emitter thereof connected to B+ and the collector thereof coupled through a resistor 93 to ground. Another PNP transistor 94 has its emitter connected to B+ and its collector connected through a resistor 95 to ground. Interconnecting the bases of transistors 92 and 94, is a pair of series connected resistors 96 and 97 with the junction thereof electrically coupled to the movable arm of the aforesaid potentiometer 88. A coupling capacitor 98 interconnects the base of transistor 92 and the collector of transistor 94, and another coupling capacitor 99 interconnects the collector of transistor 92 and the base of transistor 94. The collector of transistor 94, like the collector of the aforesaid transistor 79 of multivibrator 74, constitutes the output of low frequency multivibrator 91.

The asymmetrical rectangular wave output of low frequency astable multivibrator 91 is supplied to another integrator 101 consisting of a series connected resistor 102 and capacitor 103. Connected between the emitter of transistor 94 and ground is a resistor 95.

A controllable mixer element consisting of a potentiometer 104l is connected between the junction of series connected resistor 85 and capacitor 86 and the junction of series connected resistor 102 and capacitor 103, since said junctions constitute the outputs of the aforesaid integrators 84 and 101, respectively.

Connected to the movable arm of potentiometer 104 is a resistor 105 which, in turn, is coupled to the input of another integrator 106 consisting of the aforementioned capacitor 47 and a resistor 107. Connected in parallel with resistor 107 is another capacitor 108. As may readily be seen, the output of integrator 106 is supplied to one of the terminals of secondary winding 46 of the aforesaid transformer 45 for the purpose of signal mixing therein in conjunction with said transistor mixer-amplifier 4S.

Briefly, the operation of the subject invention as it is generally depicted in FIG. l is as follows:

Noise generator 11 produces a random frequency (substantially white noise) electrical signal which simulates cavitation noises, and this signal is coupled by means of circuit isolation transformer 12 to amplifier 13. Amplifier 13, of course, increases the amplitude of this signal to a more useful level, after which it is mixed with another signal and further amplified by the mixer network consisting of transformer 14 and mixer amplifier 15.

Said another input signal occurs in part as a result of simulating submarine boat internal engine, machinery, and gear noises by means of high frequency multivibrator 18. This multivibrator is or may be so designed as to produce a symmetrical squarewave output signal which is then shaped as necessary by integrator 19 to ultimately sound similar to `the aforesaid submarine boat internal noises. Other noises, such as screw noises other than cavitational noises, are simulated by low frequency multivibrator 22 which preferably is so designed as to produce an asymmetrical rectangular wave like signal as an output therefrom. This signal is likewise shaped as necessary by integrator 22";` to make it more nearly resemble the noise of one or more turning screws. In this case, for instance, due to the non-uniform waveform characteristic of this signal, it may sound very much like the beat that may be produced by twin screws that are not exactly synchronized in their rotational speeds.

The combining of the above mentioned pair of signals in mixer 21 makes the resulting output signal sound even more realistic for most practical purposes, and when this output signal is properly mixed with the random noise signal from noise generator 11 in mixer network 17, the total simulation signal produced thereby is most effective for many simulation purposes.

Some control of the mixing of the high and low frequency signals is effected by the manual adjustment of controlled mixer 21, in that more or less of one or the other may be added together to produce the machineryscrew noises preferred for any given operational circumstanes.

This total simulation signal is then further amplified and processed to a more useful level by driver amplifier 24, phase inverter and coupling transformer 25, and push-pull power amplifier 26 before being broadcast by transducer 27 throughout the sea where it is desired to simulate the presence of a running submarine boat.

Although primarily intended for submarine boat simulation, obviously this linvention may be so designed as to simulate other devices or vehicles of the land, sea, or space character, since so doing would be well within the purview of the skilled artisan having the benefit of the teachings herein presented. In some instances, it may only be necessary to change the frequencies and/or signal characteristics of the aforesaid multivibrators and their respectively associated integrators. Moreover, sometimes it may only be necessary to properly adjust the potentiometer constituting or included in controlled mixer 21, in order to produce the desired total simulation signal, as well.

For practical and useful purposes, the subject invention may be installed in any appropriate carrier vessel such as, for instance, a submarine decoy, or in a stationary or substantially stationary device such as a buoy, or perhaps in any appropriate combat type of device. Of course, since the preferred embodiment herein disclosed is intended to simulate submarine boat sounds, it would be installed in either to stationary or movable device that is submerged in sea water, and the simulation sounds would thus be transmitted throughout the ambient er1- vironment thereof or possibly directed toward the enemy or other parties intended to be deceived thereby.

In general, the device of iFIG. 2 functions in the same manner as the device of FIG. 1. Specifically, substantially white noise signals are generated by semiconductor diode 37 as a result of its having a high back resistance which is subject to small random variations. These variations, in turn, result in minute current fluctuations flowing through the primary winding of transformer 34 and being coupled to voltage amplifier 43. The output of this Voltage amplifier stage is transformer coupled to the next amplifier stage 48 which also serves as a mixer. The gain control consisting of potentiometer 49 is located in the collector circuit of this stage. The output of this stage is coupled to amplifier 55 which effectively serves as the driver amplifier for the power output stage. In this case, it has been found to be desirable for optimum operation to transformer couple and phase invert the output of driver amplifier 55 by means of transformer 57 before being applied to push-pull amplifiers 59 and 61. Actually, in this particular arrangement, push-pull amplifiers 59 and 61 constitute a class B amplifier. The outputs of these power amplifiers are then transformer coupled to the transducer by transformer 63, which is preferably designed to avoid saturation from the direct current transducer bias current which passes through it from the signal voltages.

To effect simulation of both internal machine noises and screw noises, multivibrators 74 and 91, are used, respectively. Like in the device of FIG. 1, multivibrator 74 of the device of FIG. 2 should preferably be designed so as to produce a high frequency squarewave output` signal, and multivibrator 91 thereof should preferably be designed so as to produce a relatively low frequency asymmetrical rectangular wave output signal, in order to effect the aforementioned noise simulations. By adjusting potentiometers 73 and 88 the frequencies of said multivibrators may be varied as desired for most practical purposes. The output of these multivibrators are then appropriately shaped by integrators 84 and 101 before being mixed in potentiometer 104. Of course, by adjusting this control, the ratio of high-to-low frequency modulating voltages may be regulated. The output of mixer 164 is then further integrated by resistors 105 and 107 and capacitor 47 before being applied to secondary winding 46 of transformer 45 for the purpose of modulating the cavitation noise signal generated by the aforementioned diode source. Depending on the proper adjustment of all the aforesaid controls and the design choice of all of the electrical components employed in this invention, the total output signal that is transmitted by transducer 65 is preferably an irregular pulsating signal with a beat closely simulating the noise of a twin-screw submarine boat.

Thermal compensation is effected by thermistors 41 and 66. In this particular case, said thermistors should be of the type that increases their resistance with an increase in temperature. Thermal compensation is, thus, effected by the automatic biasing of the base voltages of transistors 43 and 55 with temperature changes and this prevents run-away. For further temperature control, the power transistors may be mounted on an appropriate aluminum heat sink, and, of course, blower 68 may be employed to circulate cooling air throughout the entire structure.

As can readily be seen, transistors have been used throughout the subject circuit to an advantage. Consequently, the circuit has been so constructed for the use thereof, in order to miniaturize and increase the efiiciency of the subject invention without impairing its overall operation.

Obviously, other modifications and embodiments of the subject invention will readily come to the mind of one skilled in the art having the benefit of the teachings presented inthe foregoing description and the drawing. Itis, therefore, to be understood that this invention is not to be limited thereto and that said modifications and embodiments are intended to be included within the scope of the appended claims.

What is claimed is:

1. A sonic simulator comprising in combination,

means for generating a white noise signal,

means for generating an integrated symmetrical squarewave signal,

means for generating an integrated asymmetrical rectangular wave signal,

means interconnecting each of the aforesaid generating means for mixing the respective signals generated thereby into a predetermined total signal.

2. The Idevice of claim 1 wherein said means for generating a white noise signal comprises,

a semi-conductor diode noise generator,

a transformer coupled to the output of said noise generator, and Y an amplifier connected to the output of said transfor-mer.

3. The device of claim 1 wherein said means for generating an integrated symmetrical squarewave signal comprises,

a high frequency multivibrator adapted for generating a symmetrical squarewave output signal, and

an integrator connected to the output of said high frequency multivibrator.

4. The device of claim 1 wherein said means for generating an integrated asymmetrical rectangular wave signal comprises,

a low frequency multivibrator adapted for generating an asymmetrical rectangular wave output signal, and an integrator connected to the output of said low frequency multivibrator.

5. The invention according to claim 1 further characterized by means connected to the output of said mixing means for broadcasting said predetermined total signal as an acoustical signal throughout a predetermined subaqueous medium.

6. The device of claim wherein said means connected to the out-put of said mixing means for broadcasting said predetermined total signal as an acoustical signal throughout a predetermined subaqueous medium comprises,

means for amplifying said total signal to a useful level,

and

an electroacuostical transducer effectively connected to the output of said amplifying means.

7. Means for simulating the sounds that emanate from a submarine that is underway comprising in combination,

a white noise generator,

a first mixer means having a pair of inputs and an output with one of the inputs thereof effectively connected to the output of said white noise generator,

a first variable frequency astable multivibrator,

a second variable frequency astable multivibrator,

a second mixer means having a pair of inputs and an output with the pair of inputs thereof respectively coupled to the outputs of said first and second variable frequency astable multivibrators and the output thereof coupled to the other input of the aforesaid first mixer means, and

a transducer means effectively connected to the output of said first mixer means.

8. The device of claim 7 wherein said second mixer means comprises a potentiometer.

9. The invention according to claim 7 further characterized by means effectively connected to said white noise generator for the temperature compensation thereof.

10. The invention according to claim 7 further characterized by,

a first integrator connected between the output of said a first multivibrator and one of the inputs of said second mixer means, and

a second integrator connected between the output of said second multivibrator and the other input of said second mixer means.

11. The invention according to claim llt) further characterized by `a third integrator connected between the output of said second mixer means and the other input of the aforesaid rst mixer means.

12. A submarine sonic simulator comprising in combination,

a noise generator,

a first transformer coupled to the output of said noise generator,

an amplifier coupled ot the output of said transformer,

a second transformer connected to the output of said amplifier,

a mixer amplifier connected to the output of said second transformer,

a driver amplifier coupled to the output of said mixer amplifier,

a phase inverting and coupling transformer coupled to the output of said driver amplifier,

a power amplifier connected to the output of said phase inverting and coupling transformer,

a transducer coupled to the output of said power transformer,

a high frequency multivibrator,

a first integrator connected to the output of said high frequency multivibrator,

a low frequency multivibrator,

a second integrator connected to the output of said low frequency multivibrator,

a controllable mixer having a pair of inputs and an output with the pair of inputs thereof connected to the outputs of said first and second integrators respectively, `and a third integrator connected between the output of said controllable mixer and the aforesaid second transformer.

13. The device of claim 12 wherein said noise generator is la semi-conductor diode having high back resistance which is subject to small random variations.

14. The device of claim l2 wherein said amplifier coupled to the output of said first transformer includes a PNP transistor.

i5. The device of claim 12 wherein said mixer amplifier connectedto the output of said second transformer includes an PNP transistor.

16. The device of claim 12 wherein said driver amplifier includes an PNP transistor.

ll7. The device of claim f2 wherein said power amplifier is a class B power amplifier that includes a pair of PN? transistors and an output transformer connected for push-pull operation.

i8. The device of claim 12 wherein said high frequency multivibrator comprises,

a rst transistor having an emitter, a collector, and

a base,

a second transistor having an emitter, a collector, and

a base,

a B+ voltage connected to the emitter of each of said first and second transistors,

a pair of series joined resistors connected between the bases of said first and second transistors,

a ground,

a third resistor interconnecting the collector of said first transmitter and said ground,

a fourth resistor interconnecting the collector of said first transistor and said ground,

Ia fourth resistor interconnecting the collector of said second transistor and said ground,

a first capacitor connected between the base of said first transistor and the collector of said second transistor, and

a second capacitor connected between the base of said second transistor and the collector of said first transistor.

19. The device of claim 12 wherein said low frequency multivibrator comprises,

a first transistor having an emitter, a collector, and la base,

a second transistor having an emitter, a collector, and

abase,

a B+ voltage connected to the emitted of each of said first and second transistors,

a pair of series joined resistors connected ,between the bases of said first and second transistors,

a ground,

a third resistor interconnecting the collector of said first transistor and said ground,

a fourth resistor interconnecting the collector of said second transistor `and said ground,

a first capacitor connected between the base of said first transistor and the collector of said second transistor, and

a second capacitor connected between the base of said second transistor and the collector of said first transistor.

20. The invention of claim 12 wherein said third integrator comprises,

aground,

a capacitor connected between one terminal of the secondary winding of said second transformer and said ground,

a resistor connected `to the junction of said one terminal and said capacitor,

another capacitor connected in parallel with said resistor, and

another resistor connected between the junction of said parallel connected resistor and capacitor and the output of the aforesaid controllable mixer.

9 21. The device of claim 12 wherein each of said rst vand second integrators comprises a series connected resistor and capacitor with .the output thereof taken from the junction thereof and the input supplied to the nonjunction terminal of said resistor.

22. The device of claim 12 wherein said controllable mixer comprises a potentiometer.

23. The device of claim 12 wherein said third integrator comprises, a resistor, a first capacitor connected in series with said resistor,

and a second capacitor connected in parallel with said resistor.

24. The invention 4according to claim 12 further chan acterized by a cooling blower system effectively connected to a power supply through said driver amplier.

References Cited by the Examiner UNITED STATES PATENTS 2,898,587 8/1959 Nye 340-384 3,092,684 6/1963 Frankel 35-l0.4 3,165,734 l/1965 Gr-odzinsky et al. 340-384 CHESTER L. JUSTUS, Primary Examiner.

RODNEY D. BENNETT, Examiner.

R. A. FARLEY, Assistant Examiner.

Patent Citations
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3676802 *Jun 21, 1971Jul 11, 1972Us NavySubmarine propeller cavitation noise simulator
US3683113 *Jan 11, 1971Aug 8, 1972Santa Rita Technology IncSynthetic animal sound generator and method
US3706963 *Oct 7, 1970Dec 19, 1972Us NavyAcoustic target source
US3795873 *Feb 1, 1973Mar 5, 1974Us NavyMultichannel noise simulator
US3806862 *Nov 15, 1971Apr 23, 1974Bendix CorpAmplifier for sonar transmitter
US3838418 *Jun 26, 1972Sep 24, 1974Mildred MillerPest control apparatus and method
US3872472 *Dec 11, 1973Mar 18, 1975Robert G MoschgatUltrasonic system for repelling noxious fauna
US4219885 *Sep 8, 1964Aug 26, 1980The United States Of America As Represented By The Secretary Of The NavySonar target simulator
US4328485 *Nov 28, 1980May 4, 1982Potter Bronson MBinary alarm
US4618969 *Mar 26, 1985Oct 21, 1986Mitsubishi Denki Kabushiki KaishaDigital ratemeter
US5029143 *Feb 2, 1976Jul 2, 1991The United States Of America As Represented By The Secretary Of The NavyShaft rub simulator
US5299171 *Jul 20, 1970Mar 29, 1994The United States Of America As Represented By The Secretary Of The NavyTorpedo decoy signal generator
US5978646 *Jul 10, 1997Nov 2, 1999The United States Of America As Represented By The Secretary Of The NavyMethod and apparatus for simulating a lofargram in a multipath sonar system
US5978647 *Jul 10, 1997Nov 2, 1999The United States Of America As Represented By The Secretary Of The NavyMethod and apparatus for simulating autocorrelation coefficients in a multipath sonar system
US5983067 *Jul 10, 1997Nov 9, 1999The United States Of America As Represented By The Secretary Of The NavyMethod and apparatus for simulating cross-correlation coefficients in a multipath sonar system
US5995803 *Jul 10, 1997Nov 30, 1999The United States Of America As Represented By The Secretary Of The NavyMethod and apparatus for simulating a multipath sonar system
US6002914 *Jul 10, 1997Dec 14, 1999The United States Of America As Represented By The Secretary Of The NavyMethod and apparatus for simulating reverberation in a multipath sonar system
Classifications
U.S. Classification367/1, 984/376, 340/384.3, 331/78, 29/34.00R, 434/6, 327/105, 367/137
International ClassificationG10H5/00, H03B29/00
Cooperative ClassificationH03B29/00, G10H5/00
European ClassificationG10H5/00, H03B29/00