Downed Aircraft Location System and Method

Abstract

An EM emitter includes at least three orthogonal coils driven by an oscillating voltage source, with the coils being electrically in parallel or series. When used in a vehicle, particularly an airplane, and the vehicle is lost, e.g., sinks, the emitter's EM signal passes through water with little attenuation and can be detected and the vehicle located.

Claims

1. An emitter comprising: three planar surfaces, each of the planar surfaces including a coil, the coils being orthogonal to each other; and an oscillating voltage source connecting the coils in parallel or in series; at least one printed circuit board forming at least one of said planar surfaces; wherein at least one of said three orthogonal coils is formed as a spiral on said at least one printed circuit board; and wherein at least one of the planar surfaces includes a hole therethrough, with the coil on that at least one of the planar surfaces being centered at said hole.

2. An emitter according to claim 1, further comprising: an enclosure; wherein the coils and the oscillating voltage source are contained in said enclosure.

3. An emitter according to claim 2, wherein: the coils and the oscillating voltage source together generate an omnidirectional EM signal at a frequency; and the enclosure is at least semi-transparent to said EM signal.

4. An emitter according to claim 2, further comprising: an incompressible potting material filling said enclosure; wherein the coils and the oscillating voltage source together generate an omnidirectional EM signal at a frequency; and wherein the potting material is at least semi-transparent to said EM signal.

5. An emitter according to claim 2, wherein said enclosure is a right rectangular prism which is not a cube.

6. An emitter according to claim 1, wherein said oscillating voltage source oscillates at a frequency below 1000 hz.

7. An emitter according to claim 1, wherein said oscillating voltage source oscillates at a frequency between 30-200 hz.

8. An emitter according to claim 1, wherein: said at least one printed circuit board comprises three printed circuit boards; and said three orthogonal coils are formed as one spiral on each of said three printed circuit boards.

9. A locatable vehicle comprising: an airplane; and an emitter according to claim 1 in said airplane.

10. A process of locating an airplane submerged in water, the process comprising: positioning an emitter according to claim 1 in said airplane prior to said airplane being submerged; and sensing an electromagnetic signal originating from said emitter when said airplane is submerged.

11. A process according to claim 10, wherein said water is conductive seawater.

12. A process according to claim 10, wherein said emitter emits a signal a frequency between 30-200 hz.

13. An emitter according to claim 1, further comprising: six total orthogonal coils; wherein said at least one printed circuit board comprises six printed circuit boards; and wherein said six orthogonal coils are formed as one spiral on each of said six printed circuit boards.

14. An emitter according to claim 13, wherein said six circuit boards are arranged to form a right rectangular prism.

15. An emitter according to claim 13, wherein said six circuit boards are arranged to form at least three sides of a right rectangular prism.

16. An emitter according to claim 15, wherein said six circuit boards are arranged in pairs to form only three sides of a right rectangular prism, each of said pairs of circuit boards being positioned immediately adjacent to each other.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The invention of the present application will now be described in more detail with reference to exemplary embodiments of the apparatus and method, given only by way of example, and with reference to the accompanying drawings, in which

[0020] FIG. 1 diagrammatically illustrates an exemplary device including a device in accordance with the principles of this disclosure;

[0021] FIGS. 2A-2D illustrate exemplary vehicles usable with the device of FIG. 1;

[0022] FIG. 3 illustrates a portion of a second exemplary embodiment;

[0023] FIG. 4 illustrates the second exemplary embodiment;

[0024] FIG. 5 illustrates a third exemplary embodiment; and

[0025] FIG. 6 illustrates yet another exemplary embodiment.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0026] Referring to the drawing figures, like reference numerals designate identical or corresponding elements throughout the several figures.

[0027] The singular forms a, an, and the include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a solvent includes reference to one or more of such solvents, and reference to the dispersant includes reference to one or more of such dispersants.

[0028] Concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.

[0029] For example, a range of 1 to 5 should be interpreted to include not only the explicitly recited limits of 1 and 5, but also to include individual values such as 2, 2.7, 3.6, 4.2, and sub-ranges such as 1-2.5, 1.8-3.2, 2.6-4.9, etc. This interpretation should apply regardless of the breadth of the range or the characteristic being described, and also applies to open-ended ranges reciting only one end point, such as greater than 25, or less than 10.

[0030] In general terms, systems and processes of this application replace the acoustic emitter of the current Black Box with a magnetic field generator.

[0031] According to an exemplary embodiment, and with reference to FIG. 1, an enclosure, which may be a four-inch cube box, includes a magnetic field generator which emits a sufficiently strong field to be heard, that is, the magnetic field from which is detected, at kilometer distances. Additionally, since the system operates as a low frequency emitter, it works very well underwater. Accordingly, another aspect of this application is the use of these systems in and for locating downed aircraft A (FIG. 2A), on watercraft/boats B (FIG. 2B), but also can be used with missing land vehicles L (FIG. 2C), including trains T (FIG. 2D).

[0032] With reference to the exemplary embodiment illustrated in FIG. 1, a magnetic field generator system 10 includes an enclosure 12 that is potted or otherwise filled with a material 14 that will resist compression and the intrusion of water at the great depths described herein, in much the same way that current Black Boxes are constructed. While the embodiment of FIG. 1 illustrates a cube, any shape of enclosure can be used, including spheres.

[0033] Inside the enclosure 12, the system 10 includes a magnetic field generator 16. The generator 16 includes coils 18, 20, 22 which are physically oriented orthogonal to each other, thus defining X, Y, and Z directions. The coils are advantageously identical, so that the electromagnetic (EM) field generated by each is identical, which balances the generator while permitting the system to transmit signals in all directions. The coils are electrically in parallel between an oscillating voltage source 24 and ground 26. The power and frequency of the source 24 is selected with the inductance of each of the coils (and with the inherent resistance of the wire connecting the coils to ground 26) in a manner well understood by those of ordinary skill in the art, to generate an oscillating EM field through and around each coil, which is thus an EM signal that will propagate through the potting material 14 and the material of enclosure 12 and be detectable at great distances.

Exemplary Implementation

[0034] 4 inch aluminum cube, potted with epoxy [0035] Coils: three (3) orthogonal windings [0036] 200 turns per winding [0037] 0.02 inch copper diameter wire forms coils [0038] Resistance of wire=6.9 ohms [0039] Coils driven in parallel by lithium cell(s) [0040] Voltage: 3.6 v [0041] Current: 0.8 amperes [0042] Coil Inductance: 0.00395 Hy (henries) per axis [0043] Magnetic field at 1000 feet=3.510.sup.15 Tesla (at least)

[0044] The frequency generated by the emitter is selected to be low enough that its signal is not severely attenuated by water, so that location of the device in deep water can be performed. Frequencies below 1000 hz are thus particularly useful, especially those between about 30-200 hz. Additionally, the coils are positioned orthogonal to each other and held in that orientation, either by suitable supports attached to the enclosure (not illustrated), or by the potting material, or by both.

[0045] As those of ordinary skill in the art will immediately appreciate, the oscillating voltage source can be constructed of numerous existing devices which are commonly commercially available. By way of example only, the exemplary embodiment 24 includes the aforementioned lithium cell(s) as a voltage source, with a suitable oscillator, optionally including a clock circuit, which will oscillate the voltage at the desired frequency, which together function as the oscillator described herein, as well known by those of ordinary skill in the art.

[0046] For forming the structure of the enclosure itself, any material which is effectively at least semi-transparent, advantageously transparent, to the frequency(ies) of the EM radiation created by the emitter can be used, of which aluminum is useful for frequencies below 1000 hz; other materials, such as polymers, ceramics, other metals, and the like, can also be used, so long as they have the physical characteristics to form an enclosure and contain the potting material (which is also at least semi-transparent, advantageously transparent, to the frequency(ies) of the EM radiation created by the emitter) and the emitter, and be sufficiently EM transparent.

[0047] Systems as described herein can produce an omnidirectional EM signal which can be effective in debris or underwater at a range greater than 1 kilometer, and can operate 50 days or longer. Detection of the emitter's signal can be performed with numerous systems; however, the CUBE system, which is currently used and available from Sensorcom Inc. (Annapolis, Md.), and is described in U.S. Pat. No. 6,538,616 (incorporated by reference in its entirely herein), by the inventor hereof, are particularly advantageous.

[0048] As those of ordinary skill in the art readily appreciate, the several subcomponents can be modified while still forming part of this disclosure. By way of non-limiting example: the oscillating voltage source can be satisfied by many known such sources, including those of different voltage and current; the conductors connecting the coils to the voltage source can be designed in any known manner; the coils can be formed differently and/or can have a different electrical inductance, so long as they are all the same; the size of the enclosure can be selected for any convenient implementation, although an enclosure which protects the emitter itself while being sufficiently transparent to the emitter's signal, is highly preferable.

[0049] FIGS. 3 and 4 illustrate another exemplary embodiment of an emitter 30. The emitter 30 is a cube created using printed circuit boards 32. Among others, emitter 30 is advantageous because it is inexpensive and easy to manufacture. Each circuit board 32 is patterned appropriately with the coil 34, as suggested in FIG. 3. As illustrated in FIG. 4, at least three (3), and preferably six (6) printed circuit boards 32, form or are on the surface of a cube.

[0050] FIG. 4 illustrates a cubic emitter 30, in which each of the six sides is a printed circuit board 32, or is a plate with a printed circuit board 32 mounted on it. On each of the printed circuit boards 32, a spiral or coil 34 is formed, e.g., etched into the material (e.g., copper). When etched, the etching can be done on either surface of the board, or on both surfaces. By way of a non-limiting example, the spiral/coil 34 could be etched clockwise on each of the, e.g., six boards. According to yet another exemplary embodiment, an emitter is a hybrid of the emitters 10, 30, with some of the coils formed as printed circuit boards and some being traditional coils.

[0051] Inside the cube of the emitter 30 is provided a DC power supply 36, which feeds an AC generator 38 for converting DC current to AC current at the chosen frequency, as described elsewhere herein. The emitter 30 also contains at least two (or more) leads 40 (only three are illustrated) which then feed the windings on each board to generate the EM field. Thus, the interior subcomponents of the embodiment illustrated in FIG. 4 are the same as those of FIG. 1, except that of FIG. 4 does not contain the field generator 16, instead forming or including some of those components as, or mounted to, the walls of the cube. Similarly, the cube of the embodiment of FIG. 4 can be potted with an at least EM-semi-transparent material. In any of the emitters described herein, the potting material can be omitted, e.g., to save weight.

[0052] According to yet another embodiment, emitter devices as described herein can also be used to detect a person's location. By way of non-limiting example, a miner can carry with them an emitter device as described herein, in the case of a cave-in (for example, in a coal mine); alternatively, a hiker, including a soldier, can carry with them an emitter device as described herein. In all cases, if the person cannot be located by other methods, the emitter device's signal can be used to locate them as described herein.

[0053] In yet another alternative embodiment, the coils described herein are electrically connected and driven series, rather than in parallel.

[0054] In yet another embodiment, the coils described herein are not all the same size, but rather are different sizes, where the size is compensated for by the EM current.

[0055] According to yet another embodiment, other vehicles and objects can be provided with an emitter device as described herein, including underwater vessels such as a towed buoy and a submarine.

[0056] FIG. 5 illustrates another exemplary example of a coil 50 useful in the construction of an emitter, such as the emitter 30 of FIG. 4. The coil 50 is constructed of a single surface PCB 52, which is advantageously square with four sides 54 of equal length. A hole 56 is formed in the geometric center of the PCB.

[0057] A single helical trace 58 is formed on one surface of the PCB 52; FIG. 5 illustrates trace 58 only in one corner of the PCB, with several of the winds of the helix suggested by the several lines. It is to be understood that the trace 58 is continuous and helically winds around the hole 56, with two ends by which the trace 58 can be electrically connected to other subcomponents, such as those described with reference to FIG. 4 and below.

[0058] As with prior embodiments described herein, an emitter is preferably formed by six (6) of the coils 50 being assembled as the six sides of a regular cube; each pair of opposing coils forms a two-coil emitter for each of the X-, Y-, and Z-axes, as described elsewhere herein. According to other exemplary embodiments, each of the X-, Y-, and Z-axes have either one or two coils, i.e., one of the sides of the device in each direction can no include a coil.

EXAMPLE

[0059] A square washer with 4 sides has a 3 hole, formed of a single surface PCB. In the 0.5 segments or legs between the hole and the edge of the PCB (this is the thinnest section; the corners have more space), a 0.010 inch wide0.010 inch thick trace is formed. In the 0.5 leg, the trace has, e.g., 50 turns. The length of those turns is thus 1778 cm, and the resistance of the trace, R, is 4.35 ohms per PCB/plate. For the three axes, two plates are used for X, two for Y, and two for Z on the opposite sides of the 4 cube, requiring six plates total. R per axis thus equals 8.7 ohms.

[0060] Table 1 below shows a number of examples of the attenuation by sea water at 5 hz of a signal generated by an exemplary embodiment being a 4 cube with PCB sides and a 3 hole.

TABLE-US-00001 TABLE 1 Attenuation by sea water at 5 hz (Wavelength at 5 hz = 694 m; Attenuation = 55 dB/m Depth (m) 100 200 300 350 Wavelength (m) 694 694 694 694 dB/wavelength 0.14 0.29 0.43 0.89 Attenuation (dB) 1.38 1.95 2.65 2.96 Magnetic field with no attenuation 45.2 5.68 1.68 1.0 (pico Tesla) Magnetic field with attenuation 25.1 2.92 0.65 0.13 (pico Tesla)

[0061] As a further alternative, the electronics and batteries for driving the six coils (see, e.g, FIG. 4) are contained in a fiberglass box which forms a 4 cube, and the PCBs 50 are attached to all six surfaces of that cube.

[0062] In yet another exemplary embodiment, a right rectangular prism 60 (also referred to as a rectangular cuboid or a rectangular parallelepiped) is formed of PCBs, instead of a regular cube, with coils on the interior face of up to six of the sides of the prism, in one or more of the ways described elsewhere herein. More specifically, the lengths of the sides of the prism 60 are not identical. By way of a non-limiting example, the prism 60 has sides of 2, 3, and 4, and thus has three rectangular cross sections: 23; 24; and 34. Calculations of background data for the embodiment using prism 60 and nickel metal hydride c cell batteries are in the tables below:

TABLE-US-00002 TABLE 2 Magnetic field strength over land distance (nT = nano Tesla; pT = pico Tesla) Distance (m) 200 400 600 800 1000 B (1) 5.25 nT 0.66 nT 0.194 nT 82 pT 42 pT B (2) 6.18 nT 0.77 nT 228 pT 96.5 pT 49.4 pT B (3) 7.46 nT 0.93 nT 276 pT 117 pT 59.7 pT B (Noise) 0.002 nT 0.002 nT 0.002 nT 0.002 nT 0.002 nT

TABLE-US-00003 TABLE 3 Magnetic field strength over distance in seawater (nT = nano Tesla; pT = pico Tesla) Distance (m) 200 400 600 800 1000 Attenuation (dB) 2.0 3.98 7.94 15.9 31.6 B(1) (att) 2.62 nT 0.17 nT 24 pT 5.16 pT 1.33 pT B(2) (att) 3.09 nT 0.19 nT 28.9 pT 6.07 pT 1.6 pT B(3) (att) 3.73 nT 0.23 nT 34.8 pT 7.4 pT 1.9 pT

[0063] Nickel metal hydride c cells could be replaced with lithium c cells, and the magnetic field generated would be much greater. Because lithium batteries are subject to different government regulation in many jurisdictions, they are sometimes not allowed under some circumstances and uses (for example, in commercial aircraft). In other uses, such as on land or on water (miners or boats), lithium batteries can optionally be used.

[0064] By way of another non-limiting example, a right rectangular prism 60 can be formed to be 244 (e.g., inches), with NiCd C-cells producing 1.55 v. Two, single-sided PCBs, or alternatively one double-sided PCB, form, or are mounted on, each face of the prism, and each face optionally is formed with a hole in its center.

[0065] Vertical [0066] L=27.94 cm/turn (of the coil) [0067] area=0.00016 cm.sup.2 [0068] R=7 ohms

[0069] Horizontal [0070] L=38.1 cm/turn [0071] area=0.00016 cm.sup.2 [0072] R=9.53 ohms

B=NIA/D.sup.3

Therefore:

[0073] Vertical: N=25, I=1.55/7=0.22 amps

[0074] Horizontal: N=25, I=1.55/9.53=0.16 amps

[0075] The magnetic fields for the vertical coils at water depth, for N=25, I=0.22, and A=0.0052 are thus:

TABLE-US-00004 Distance (m) 200 400 600 800 1000 B (+Y) 3575 447 132 56 28.6

[0076] The magnetic fields for the horizontal coils at water depth, for N=25, I=0.16, and A=0.0103 are thus:

TABLE-US-00005 Distance (m) 200 400 600 800 1000 B (up) 5150 644 191 80.5 41.2

[0077] Therefore, the magnetic fields (for two emitter plates) are:

TABLE-US-00006 Distance (m) 200 400 600 800 1000 B (X) 7150 894 264 112 57.3 B (Y) 7150 894 264 112 57.3 B (Z) 10300 1288 382 161 82.4 B (n) 2 2 2 2 2

[0078] With attenuation factor of sea water at depth being:

TABLE-US-00007 Distance (m) 200 400 600 800 1000 Attenuation factor 2 3.98 7.44 15.9 31.6

[0079] Results in the following magnetic fields in seawater at depth:

TABLE-US-00008 Distance (m) 200 400 600 800 1000 B (X) 3575 225 33.3 7.04 1.8 B (Y) 3575 225 33.3 7.04 1.8 B (Z) 5150 324 51.3 10.1 2.61 B (n) 2 2 2 2 2

[0080] According to other exemplary embodiments, the circuits including the coils can be driven using single direction pulses, e.g., at 5 pulses per second; while the shape of the pulse selected can be any shape, a square wave pulse is preferred. By way of a non-limiting example, using NiCd batteries totally 8 amp-hours:

I(X)=0.22 amp/2=0.11 amp; operating time t=8/0.11=73 hrs

I(Y)=0.22 amp/2=0.11 amp; operating time t=8/0.11=73 hrs

I(Z)=0.16 amp/2=0.08 amp; operating time t=8/0.08=100 hrs

Note: operating time can be increased by transmitting at intervals

[0081] Importantly, the total operating time of the transmitter can be increased by transmitting at intervals rather than continuously, by a number of ways. For example, the duty cycle of the circuit can be modified in recognized ways so the coils are energized, and thus transmit, for 10 second, and deenergized for 100 seconds, i.e., 9% duty cycle; other values of the duty cycle can be used. Using this as an example, the battery life for each of the coils, that is, directions, is: X, Y=73 hrs10=730 hours 30 days of transmission; Z=100 hrs10=1000 hrs42 days of transmission.

[0082] While the invention has been described in detail with reference to exemplary embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention. The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents. The entirety of each of the aforementioned documents is incorporated by reference herein.