Percussive Communications System Including Earthquake and Mine Rescue PCT/US2007/022563

Description

FIELD OF THE INVENTION

The present invention relates to a communications system via compressible medium including through-the-earth communications and, more particularly, to a communications system which encodes the message data as differential timing of percussive pulses or percussive pulse bursts.

BACKGROUND OF THE INVENTION

Disasters often leave survivors' trapped underground. In order to mount an effective and timely rescue effort, rescuers need to have immediate knowledge of the precise location of survivors and the precariousness of their situation. However, mine communications are usually disrupted by the same disaster that entrapped the miners. Since many mine disasters occur in countries that do not have existing communications infrastructures, emergency communications system must be wireless, inexpensive and portable, it must be built within the "intrinsic" safety Jimits of mine use and it must be simple to operate. Since the rescue window is often measured in hours, only rescue systems that are carried by the persons to be rescued which work with systems already in place have a chance of being successful.

Through-the-earth signaling by the tapping, hammering or other percussive forces is often the only means of communications for victims trapped in a mine disaster or trapped in the rubble of an earthquake. Other through-the-earth signaling for mines most often utilizes mine phones, mine leaky feeder systems or mine PED ₁ low frequency using loop antenna, installations. The weakness of these systems is their dependence on a relatively fragile underground transmission infrastructure or antenna and repeater infrastructure in the mine.

The mine phones and leaky feeder systems are based on cables that may be easily cut in mine disasters. This infrastructure does not exist for underground or under rubble earthquake rescue systems. The weakness of radio systems is the limited propagation of radio signals through-the-earth or rubble. While the range of radio-based systems can be extended by repeaters, a repeater system has a fragile and often complicated infrastructure. In addition, radio-based systems have been handicapped by lack of approved permissible hand-held radios as such systems are not intrinsically safe in mines. The National Institute for Occupational Safety and Health has summarized the status of mine communications and location systems as follows: "Presently no system has been demonstrated that meets the most basic requirement for emergency communications, other than the PED system, which is limited in application based on the characteristics of the mine overburden, electromagnetic interference issues, and other application constraints." Seismic systems for detection and location of miners were extensively studied through the seventies when the focus shifted to radio, fiber and other more modern technologies. However, except for PED systems this promise is yet unfulfilled and since PED - systems require high power to penetrate the earth, implementations are most often used as signaling from the surface to the miner and then at data rates measured in bits per second, which are similar to the data rates of the simplest form of the herein disclosed inventions for percussive communications systems.

In 2007 trapped miners in the United States are still employing systems similar to the long standing five step percussive signaling plan; 1. Barricade, 2. Listen for three shots, 3. Signal by pounding hard 10 times, 4. Rest for 15 minutes, 5. Wait until you hear five shots, which signals you are located and help is on the way. Recent mine disasters in 2007 have demonstrated that percussive systems are often the only available communication systems for victims trapped when the existing mine communications are severed or in earthquake rubble. The herein described invention provides a method to send and receive messages by percussive pulses using relatively simple or very low powered equipment. It

fulfills a long standing need for a wireless, low cost, low power, intrinsically safe communications system that fulfills the two highest priorities of mine rescue, immediate knowledge of the precariousness of their situation and determination of the location of trapped survivors.

The ideas that underlie this disclosure were motivated by previous multidisciplinary research, in the area of fiber optic sensors for seismic studies and earthquake detection at the Stevens Institute of Technology, one of America's oldest engineering universities. Technogenesis is the educational frontier, pioneered by Stevens, where faculty, students and industry jointly nurture research concepts to commercialization and back to the classroom. It is more than technology transfer; it is part of the Stevens educational experience and creates a climate of innovation and enterprise across the campus.

SUMMARY OF THE INVENTION

The percussive pulse communications system uses a method of communicating with successive percussive pulses wherein information is encoded in the differential timings of successive single percussive pulses or pulse bursts, using a circular pendulum, a watch second hand, or a low power computer, cell phone, or microprocessor based device to generate the periodic timing base for the communications. Messages are either pre-encoded as standard messages, encoded by hand, or machine encoded with a microprocessor based device, utilizing the percussive communications method. Encoding may also be accomplished manually using very simple rules.

The invention discloses both one way and two percussive communications systems. The simplest preferred implementation allows a trapped person to send a message using any available means to generate percussive pulses, e.g. rock striking rock. With only a weight, a string and instructions, a trapped person is able to send a message encoded as percussive pulses with the message

encoded as the spacing between the percussive pulses. A receiver of the message is able to decode the message with a circular pendulum by synchronizing the receiving pendulum with the sending pendulum during the header preceding the message, and then noting whether the received percussive pulses which form the message arrive during the leading, center or lagging interval of the circular pendulum.

A microprocessor based implementation, which may be a credit card sized calculator or an applications program in a cell phone or other microprocessor based device, is used to input the message and calculate percussive pulse burst timing using a percussive communications method. The device signals the sender when the next percussive pulse must be initiated. The receiver of the message provides an input to the device, such as a button push, when each percussive pulse arrives and the applications program converts the input into a message using a percussive communications method.

For miners trapped far under the earth in a refuge bay, a percussive communications method is used to send messages to the refuge bay. Seismic thumpers, powered by emergency reservoirs of compressed air, provide alternative emergency communications from the rescue bay or relay weaker percussive pulse communications from nearby miners to the surface.

Recent rescue attempts in the United States have attempted rescue communications by drilling a narrow hole deep into the earth and percussively tapping on the drill casing hoping the trapped miners would tap back to signal that they were still alive. Microphones and cameras were also lowered down the drill casing in the hope that the drill casing would exactly penetrate the chamber containing the trapped miners. An alternative approach is to lower a seismic sensor and percussive pulse generator into the drill casing which at the estimated depth of the trapped miners would send and receive percussive pulses through the drill casing to communicate with the miners. Since equipment the

miners need to send and receive message can be as simple as a circular pendulum and instructions, as compact as a credit card, miners can go beyond signaling only their presence by tapping and can send messages to and receive messages from the rescue team.

People are often trapped under the overburden of an earthquake, and even though they have wireless communications device with them, such devices are often unusable because of the additional radio frequency path loss of the overburden. The percussive pulse rescue communications system uses the disclosed percussive pulse communications system to send to a rescue team the unique identification of the trapped person. This unique identification allows the database of the rescue communications system to inform the rescue team of the technical specifications of the wireless equipment and the personal profile and requirements of the trapped person. Once the specifics of the wireless equipment are known, specialized equipment can be employed to overcome the path loss of the overburden and communicate with the trapped person. Alternatively a percussive communications method running as an application on the wireless device is used to pass messages between the trapped persona and the rescue team.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG 1. is a block diagram of the percussive pulse unidirectional communications system.

FIG 2. is a diagrammatic representation of a circular pendulum timer showing calibration sheet with the intended path of circular pendulum.

FIG 3. is a diagrammatic representation of a circular pendulum timer with center pivot support showing the calibration sheet.

FIG 4. is a diagrammatic representation of a circular pendulum timer with segmented center support showing calibration sheet.

FIG 5. is a diagrammatic representation of a timing unit utilizing the second hand of a watch.

FIG 6. is a diagrammatic representation of a bi-directional percussive communications system with 3 symbols in each direction.

FIG 7. is a diagrammatic representation of a bi-directional percussive communications system with multiple symbols in each direction.

FIG 8. is a diagrammatic of the mine rescue communication system using seismic sensor and seismic generator in borehole.

FIG 9. is a block diagram of the percussive pulse rescue system.

DETAILED DESCRIPTION

This section is a detailed description of the drawings with discussion of the principal of operations and concepts underlying the invention.

The invention discloses both one way and two percussive communications systems. Percussive pulses are generated by tapping, hammering, explosions, very short releases of compressed air, pneumatic driven thumpers, or other percussive forces that generate P-waves, S-waves, Love waves or Raleigh

waves in the compressible medium that conveys these waves from the sender to the receiver. The trapped miner might generate a percussive pulse with a hammer, a heavy timber or generate a burst of percussive pulses by briefly activating a pneumatic drill in contact with the mine wall. Messages sent as a percussive pulse or percussive pulse busts have the message data encoded as the time interval between the percussive pulses or pulse bursts.

A pulse burst from a pneumatic drill initiated by a trapped miner may vary in length depending on the physical state of the trapped miner who triggers the drill or may vary in frequency depending on the particular pneumatic drill or the pressure of the air source powering the drill. Therefore pulse busts are more likely to be similar across successive pulse bursts within the same percussive pulse burst message than from different messages sent by trapped miners using different pneumatic drills. This invention discloses three forms of pulse bursts beyond a pulse bust consisting of single percussive pulse. The first form of pulse bursts disclosed is more or less regularly spaced impacts percussive pulses where the number of percussive pulses in a burst may vary in each pulse burst in the message with different levels of accuracy in the timing of the percussive pulse pattern in the burst, depending upon whether or not the pulse burst is created by a person or electrical or mechanical timing of the percussive pulse generator.. An example is a pneumatic drill which generates a more or less constant frequency burst whose duration may or may not be well timed; however, since the message depends on determining the start of the pulse burst, more percussive pulses can only help in this determination. The second form of pulse bursts disclosed uses the very same pattern of percussive pulses for each pulse burst in the message. The third form of pulse bursts disclosed uses a pseudorandom generator to create a unique but predictable pattern for each successive percussive pulse burst. A similar pseudorandom generator at the receiving location predicts the pattern for subsequent pulse bursts and this provides improved pulse burst detection in the presence of noise. For each of the disclosed pulse burst forms, signal processing techniques can improve the

message quality and/or processes weaker signals in the presence of noise. The third form of pulse bursts disclosed improves the possibility of receiving a message even when another message sometimes overlaps with the desired message.

A percussive pulse unidirectional communications system is shown in FIG 1. The sending unit at the first location 1 uses a percussive communications encoding method 2 whose timing is controlled by a timing unit 3 to convert the message 4 into percussive pulse timings 5 which the percussive pulse generator 6 uses to generate percussive pulse bursts 7 . The percussive pulses travel as P-waves, S-waves, Love waves or Raleigh waves to the receiving unit at a second location 8 where percussive pulse detection 9 is use to determine the percussive pulse timing 10 which the percussive communications decoding method 11 whose timing is controlled by a timing unit 12 uses to yield the message 13. This invention discloses several preferred embodiments for percussive communications encoding methods and several preferred embodiments for timing units. The percussive pulse generation and percussive pulse detection may be accomplished by well known hardware and software combinations or manually by a person.

The simplest preferred embodiment of the invention for the encoding method and timing unit is to use a circular pendulum timer of FIG 2 whose angular speed is adjusted such that the path of the weight 14 at the end of the circular pendulum traces out a circle of specific diameter 15 on a calibration drawing 16 that lies just below the path of the circular pendulum. A lower pendulum angular velocity traces out a smaller circle than the calibration drawing and a higher pendulum angular velocity traces out a larger circle. Therefore, a predetermined period of the circular pendulum occurs when the circular pendulum path corresponds to the circle on the calibration drawing. Three points on an arc of the circle of

specific diameter 15, whose length is less than the diameter of the circle, define the leading 17, center 18 and lagging 19 points, which correspond to the encoded symbols of the message; zero symbol, repeat symbol and one symbol respectively. In this simplest preferred embodiment, a periodic pulse burst corresponding to a symbol of the encoded message is sent for each successive periodic cycle of the circular pendulum. For example, when the weight of the circular pendulum 14 passes over the leading point 17, a percussive pulse burst corresponding to a 0 symbol is sent and similarly when the weight 14 passes over the center point 18 a percussive pulse burst corresponding to a repeat symbol is sent and when the weight 14 passes over the lagging point 19 a percussive pulse burst corresponding to a one symbol is sent. The regular period of the circular pendulum is the time base of the timing unit. It is the differential timing between leading, center and lagging percussive pulse bursts that is the basis for the percussive communications encoding method. As the circular pendulum traverses the circle of specific diameter, the position of the pendulum relative to a reference point defines a phase angle 20 relative to the center point. The leading percussive pulses occur when the weight 14 is above the leading point 17 which is before the weight passes over the center 18; thus they are said to lead the center pulses in both time and phase angle 20.

A handheld circular pendulum of FIG 2., which consists of a pivot for flexible support 21 which extends from the pivot for flexible support 22 to the weight 14 most stably traces out a circle of specific diameter 15 on a calibration sheet 16 that lies just below the path of the circular pendulum when the person who uses the circular pendulum is able to both maintain the proper angular velocity and in addition is able to hold the upper pivot point of the flexible support joining the weight at the bottom of the circular pendulum directly over the circle of a specific diameter on the calibration drawing 15.

Fig. 3 shows a circular pendulum timer with a support 16 rising from the center of the circle of specific diameter 17 on a calibration sheet 18 to a pivot for the

flexible support 19 which is joined to weight 20 at the bottom of the circular pendulum directly over the circle of a specific diameter 17 on the calibration sheet 18. The attachment point of the flexible support 21 joining the weight to the pivot point of the support or the attachment point of the weight 20 is adjustable to allow for different lengths of the support and therefore for different repetitive timing of the circular pendulum. The support, when held vertical and wobbled slightly to control the movement of the circular pendulum makes it easier for a person to operate the circular pendulum such that the pivot point remains centered over the circle of specific diameter. This center pivot support 16 shown in Fig.3 is either of fixed length or a telescoping support that can be compressed to redlice its size for portability and expanded for operational use. Adjusting the length of the center pivot support 16 and adjusting the length of the flexible support 21 changes the period of the circular pendulum.

Fig. 4 shows a circular pendulum timer where the loop over pivot of flexible support 22 and the loops of the flexible support 23 2425 connecting the pivot of the circular support 26 to the weight 27 are uniformly spaced in increments from 0.5 in to 108 inches and where the segmented center support 28 from the center of the circle of specific dimension 29 to the pivot of flexible support 22 is comprised of cylindrical segments of 0.5 in to 108 inches in length and these segments are interconnected by cylindrical plugs that are smaller in outer diameter than the inner diameter of the loops. Thus the periodic timing can be changed by selecting the number of segments to use in the support. Longer percussive pulse travel paths imply slower periodic timing to allow for travel time when bi-directional percussive communications are used.

The percussive pulse burst message can be a binary message, a Morse code message, or other codes that use two symbols. Consider a binary message where the first step of encoding is to convert each binary bit of the message followed by the same binary bit into the binary symbol for that bit followed by the repeat symbol. The second step of the encoding is to converts symbol into a

percussive pulse burst beginning at a leading point, a center point or a lagging point as shown in Fig. 2. As an example, let the leading point timing represent a zero symbol, the center point represents the repeat symbol and the lagging point represent the one symbol. When a binary 0 is followed by a binary 0, the first binary 0 is transmitted as a leading percussive pulse and the send binary 0 is transmitted as a center percussive pulse which is the symbol for repeating the previous pulse. Similarly, when a binary 1 is followed by a binary 1 , the first binary 1 is transmitted as a lagging percussive pulse and the send binary 1 is transmitted as a center percussive pulse. The advantage of transmitting a repeated character as a center percussive pulse is that the same symbol is not sent repeatedly when a string of 1's or O's occurs. Since the absolute timing from a hand held circular pendulum timer may not be stable over a long string of repeated binary 1 's or binary O's, the synchronized timer at the receiving end may lose track of the absolute timing (reference phase angle) of the center pulse from which timing between other pulses is calculated. A repeat symbol makes it easier to maintain synchronization at the receiving timer since this synchronization symbol (repeat symbol) appears often, even when the message consists of long strings of repeated bits. Said another way, even though the center frequency of the timing unit, e.g. a circular pendulum, may drift over time, adding a repeat symbol will increase the number of symbol transitions containing synchronization information (repeat symbols) improving synchronization when drift occurs or when long strings of repeated characters are transmitted. Even in the case where a long string of alternating 0 and 1 symbols are sent, since the center percussive pulses, timing wise, are between the 0 and 1 bits, the center reference frequency is at a phase angle between leading and lagging percussive pulses and therefore easily determined. Furthermore, since two repeat symbols, center pulses, are not permitted in a message except in the header, a simple header may consist of some number of center pulses and thus will, not only be easily recognized at the start of the message, but will also allow the receiver of the message to synchronize with center pulses which is the obvious choice as the zero phase angle reference.

Consider an example where the circular pendulum path is a circle and three points on the circle are established corresponding to leading, center and lagging percussive pulses and for which the point for the center pulses is midway between the leading and lagging pulses and furthermore that the arc is less than half the diameter of the circle. To send a message which consists of a binary 1 followed by a binary 1 followed by a binary 0, [1 ,1 ,0], the trapped person first controls the binary pendulum such that the path of the pendulum follows the circle on the calibration drawing and the pendulum repeatedly passes over the three points on the circle designated leading percussive pulse (binary 0), center percussive pulse (repeat) and lagging percussive pulse (binary 1) in turn. To send the [1 ,1 ,0] message, the first bit is sent the first time the circular pendulum traverses the circle by generating the first percussive pulse or pulse burst when the circular pendulum passes over the binary one point, the second time the circular pendulum traverses the circle generating the second percussive pulse or pulse burst when the circular pendulum passes over the repeat pervious binary state point and the third time the circular pendulum traverses the circle generating the third percussive pulse when the circular pendulum passes over the binary zero point. Decoding the message at the receiving location is simplified when the pendulum in the receiving timer or its digital equivalent is synchronized with the transmitting. Consider a header consisting of 10 repeat symbols which results in sending 10 center pulses. In this simple header, with uniform differential timing between the successive percussive pulses, the message receiver has an opportunity to identify the fixed rate regular sequence of percussive pulses and synchronize the receiver timer with the transmitter timer.

During the message, synchronization of the timing unit of the receiver is simplified, as both the sender and the receiver have a circular timer of the same physical dimensions, and therefore the circular pendulums have the same periodicity. If the synchronization of the receiving unit begins to fall behind, the

trapped miner has only to increase the diameter of the path of the circular pendulum to catch up. Furthermore, when the leading, center and lagging points are less than half the diameter of the circle, the two ends of the arc are readily apparent, as the ends of the arc are determined by the times that zero symbols and one symbols arrive. For communications in both directions, the timing units in both the forward and reverse message direction utilize an arc that is less than half the diameter of the circle,

A second preferred embodiment of the timer is the use of the second hand on a watch. FIG. 5 is a diagrammatic view of a watch with second hand functioning as the timing unit wherein a time between 31 seconds and 59 seconds inclusive may be chosen for the timing for a leading percussive pulse, 60 seconds is chosen for the timing for an center percussive pulse, and a time between 1 second and 29 seconds inclusive may be chosen for the timing for an lagging percussive pulse. For example, an operational implementation of FIG. 5 uses 40 seconds for the leading point timing 30 for a leading percussive pulse burst, 60 seconds for the center point timing 31 for a center percussive pulse burst, and 20 seconds for the timing for a lagging point timing 32 lagging percussive pulse burst.

A third embodiment is a credit card sized, microprocessor controlled calculator on which the user can input the message and the timer and encoding logic within the calculator signals the sender when to generate the next percussive pulse burst of the message. A voice and/or tactile input is used to enter the arrival or pattern of received pulse bursts, which the microprocessor controlled calculator processes to recover and display the message or convert the message by text to speech for the user. The small size of this embodiment enables its storage within the helmet of the miner or with a shock resistant protective container that easily slips into a pocket. This embodiment accepts a wide range of external DC power which enables alternative sources of power including power from a miner's lamp, should the internal batteries fail.

A fourth embodiment is a hand held microprocessor based device with input and output capabilities, including an alpha-numeric keyboard and/or functional buttons or their tactile equivalent, such as a hand-held computer, or a hand-held computer with radio frequency communications such as a cell phone or PDA. For receiving a percussive pulse message the user inputs the pulse burst arrival to the microprocessor each time a percussive pulse burst is detected and the microprocessor controlled calculator decodes the message utilizing a Percussive Communications Method and displays the message to the user. The capability of inputting or selecting a message, for example, the number of the closest location marker in the mine, meets the long sought goal of providing the location of the trapped miner. Preset messages stored in the device in multiple languages to signal the air quality or medical needs provide rescuers with crucial information. In a mine where miner's headlight batteries are measured in hours, providing an audio or visual clue as to when to send the next percussive pulse in a message enables more accurate messages under less than desirable circumstances. Providing an audible or visual example of the pattern of a percussive pulse burst improves the message quality when a specific percussive pulse pattern is used for each burst or when each successive pulse burst is a unique pattern generated by a pseudo random pattern generator. A button to enable the miner to signal the microprocessor that a pulse burst has arrived or alternatively to input the pattern of each received pulse burst as it arrives automates the collection of percussive pulse burst arrival times. The microprocessor, after decoding a message displays the message and/or by text to speech reads the message to the miner. A further improvement of this embodiment is the addition of an interface to a source of percussive pulses such as a percussive drill or a thumper that will create high energy percussive pulses. A further improvement of this embodiment is the addition of an interface to one or more sensors, which detect the received percussive pulses as P-waves, S- waves, Love waves or Raleigh waves, thereby automatically sensing the arrival

of a percussive pulse burst and convey such percussive pulse timing information through the interface to percussive communications decoding method.

A fifth embodiment is a bi-directional percussive pulse system in which the periodic percussive pulse bursts in the reverse direction are timed to occur between the periodic percussive pulse bursts in the forward direction. The timing units are synchronized in each direction. Such a bi-directional communications system can simultaneously send independent messages in both directions or operate in loopback mode to confirm reception. Fig. 6 shows a bi-directional percussive communications system which utilizes 3 symbols in each direction. The sending first location 33 transmits to the receiving second location 34 percussive pulse bursts 35 representing a zero symbol 36 or a repeat symbol 37 or a one symbol 38 during the first part of each transmission/reception cycle which begin to arrive at said receiving second location 34 during the zero signal interval 39, the repeat signal interval 40 and one symbol interval 41 respectively. During the remainder of the transmission/reception cycle the sending second location 42 transmits to the receiving first location 43 percussive pulse bursts 44 representing a zero symbol 45 or a repeat symbol 46 or a one symbol 47 during the send part of each transmission/reception cycle which begin to arrive at said receiving second location 43 during the zero signal interval 49, the repeat signal interval 50 and one symbol interval 51 respectively. The not used time intervals 52 53 54 55 provide for travel time for the percussive pulse bursts between the first and second location.

A sixth embodiment is a system for communicating by percussive pulses which uses Percussive Encoding and Decoding Methods that enables multiple bits of the message to be sent as percussive pulse bursts. Fig. 7 shows a bi-directional percussive communications system with multiple symbols for each direction. The first location timing cycle 56 and the second location timing cycle 57 are synchronized. During each periodically occurring timing cycle, it is possible to send a single symbol and also to receive a signal symbol from each location.

The timing cycle which conveys information as percussive pulse bursts 58 from the sending first location 59 to the receiving second location 60 is segmented into an integer number of time intervals, corresponding to K 61 62 symbols per cycle in the forward direction. The timing cycle which conveys information as percussive pulse bursts 63 from the sending second location 64 to the receiving first location 65 is segmented into an integer number of time intervals, corresponding to L 66 67 symbols per cycle. Each symbol is sent as the differential timing between successive pulse bursts in each symbol cycle. As each symbol represents a one or more message bits, multiple bits of the message can be sent in each direction during a cycle. Thus, if K equals 26 in the forward direction, a letter of the alphabet can be transmitted for each symbol sent and if L equals 128 in the reverse direction then an ASCII character can be transmitted in each symbol sent. The maximum symbol rate will depend on the percussive pulse transmission characteristics of the compressible medium separating the sender and the receiver, however, high power seismic generators, accurate timing, and well chosen location rescue bays and surface communications points permit data rates faster than magnetic communications during quiet seismic periods that would be enforced at regular intervals during a mine rescue operation and unlike magnetic communications (PED), percussive pulse communications systems are equally effective in both directions.

A seventh embodiment is a bi-directional percussive pulse system that can operate as a backup communications system where miners trapped in a refuge bay where the primary communications from the refuge bay to the surface are cut by a mine disaster. The use of a high pressure compressed air reservoir in the refuge bay to generate powerful seismic pulses with an air driven seismic generator (thumper) enables the sending of messages including compressed voice messages from deep in the earth unidirectional or bi-directionally. The backup power source for the seismic generator and the percussive pulse

communications systems includes but is not limited to compressed air, chemical power generators, batteries, fuel cells and electric generators.

An eighth embodiment is a mine rescue communications system that uses a seismic sensor and seismic generator in a borehole which is diagrammatically shown in FIG 8. When a miner is trapped, small shaft boreholes are often drilled to the last known working location of the miners. If a mine chamber is entered by the drill casing at the hoped for depth during the drilling, microphones or cameras are lowered into the borehole to assist in the search for the miners and the borehole casing is percussively struck hoping that the miners response will be heard by the lowered microphone. However, the chance that the borehole will reach the very chamber where the miners are located is not very great. In this embodiment, percussive pulse originating and sensed within the borehole are used to communicate through-the-earth to the trapped miners. A seismic sensor and seismic pulse generator 68 are lowered into the borehole near the assumed location of trapped miners. Percussive pulse communications 69 from the seismic sensor and seismic pulse generator 68 convey messages to and from a trapped miner in chamber 70. The seismic sensor and seismic pulse generator 68 communicate with and are powered by the surface rescue location 71 by the connection to seismic sensor and seismic pulse generator 72. A mechanical attachment is used to transmit percussive pulses through the borehole 72 casing from the seismic sensor and seismic pulse generator 68.

A ninth embodiment is a Rescue Communications System, shown in Fig. 9, which is especially useful for earthquake rescue communications with a person trapped under overburden 73 consisting of a combination of rubble including possible voids, water or earth where the person trapped under overburden is in possession of a radio frequency communications device 73, such a cell phone, but the device is not able to connect because of the additional path loss of the overburden 74. If the trapped person is able to send their unique identification by percussive pulse communications 75 to the rescue location, then specialized RF

equipment 76, such as powerful transmitters using the specific frequencies and protocols of the trapped person's radio frequency communications device, sensitive receivers and directional antennas, can overcome the path loss of the overburden. The rescue location 76 utilizes a means to detect the received percussive pulses as P- waves, S-waves, Love waves or Raleigh waves, and to measure the absolute timing of the beginning of said received percussive pulse bursts or the relative timing between the start of said successive pulse bursts. The means include percussive pulse detectors such as seismic sensors, geophones, microphones or acceleration sensors capable of detecting percussive pulses as P-waves, S-waves, Love waves or Raleigh waves that are transmitted by compressible media from the person(s) trapped under overburden 73 and detected at the rescue location 76. In areas prone to earthquakes, where significant danger exists in people being trapped in the collapse of their own homes or other buildings, a novel way to detect percussive pulses sent by victims trapped in the collapse of their own homes or other buildings is by embedding percussive pulse devices or sensors in the foundations the homes and buildings. The means to detect percussive pulses is installed in the foundations, and other areas such as structurally protected areas or rescue chambers, during initial construction or by subsequent modification and the output of these percussive pulse detectors is routed to an above ground access port accessible by rescue workers. For example, one or more fiber optic seismic sensors are embedded in the foundation near to or at the inner walls and the fiber optic connection from the seismic sensor to the above ground access port has a standard interface used by rescue works. While it is not obvious, such a public access port for earthquake rescue is conceptually similar to the standard access port to the sprinkler system used by firemen. Alternatively, the percussive pulse bursts received by the sensor or device which detects percussive pulse bursts is forwarded via the house or building alarm system. Outputs from analog technology sensors and devices which detect percussive pulse bursts are digitized and then sent as data by the alarm system. Outputs from digital technology devices and sensor which detect percussive pulses are forwarded by the alarm system as a digital

message. Earthquakes often cause power failures, therefore percussive pulse devices or sensors embedded in the foundation or structural members that are powered from the above ground access port are a novel solution to the long standing problem of sensing percussive pulse communications after an earthquake. When the earthquake also obstructs the access port another approach is required. A novel way to power devices or sensors embedded in the foundations of buildings or in building structural members rescuers is using \ magnetic or radio frequency energy from the surface to power the sensor and the wireless links which transmit the output from the sensors to the rescuers on the surface.

When a wide range of RF devices of diverse wireless frequencies and protocols, such as CDMA, TDMA ₁ Wi-Fi, IP over multiple wireless protocols, are in the possession of multiple persons trapped under overburden 73, identifying and transporting the specific equipment to overcoming the overburden path loss is a major resource allocation problem following a earthquake or shallow mine disaster. However, if a trapped person is able to convey their unique rescue identifier, using percussive pulse communications 75, to the rescue location 76, then a database query 78 to the rescue application server 79 will inform the rescue location 78 by a database response 80 of the specific RF device specifications of the trapped person and other status information stored by the trapped person in the server. The database underlying the rescue server 79, which has been updated at an earlier time by the trapped person, contains the information for specifying the particular equipment needed to overcome the overburden path loss.

For persons not in the rescue server database, they can send their cellular address by the pulse communications link 75 and are identifiable by the cellular service provider, however; other features of the disclosed percussive pulse rescue system are not available, such as downloads to their cell phone with percussive pulse communications application or personal user data (for example

health advisories or preconfigured messages to friends and family when specific events trigger specific messages.)

When users of the rescue database 79 adds additional RF communications devices to its database, the radio frequency (RF) Link 77 provides a means to download to the RF communication device, the percussive pulse communications applications i; the unique rescue identifier, personalized user data and preconfigured messages for the users specific RF communications devices.

The rescue database 79 together with the rescue application server 81 allows users to configure predetermined messages on the web, select preconfigured messages, such as the unique rescue identifier message, and download this information to their RF communications device. When a person is subsequently trapped under the overburden, they send their unique identifier by running the percussive pulse communications application using a percussive communications method application on their RF communications device (e.g. cell phone) which will signal the user by audio or display as to when to send the percussive pulses in the message 75. When radio communications through the overburden are not possible, trapped victims send messages by running the Percussive Communications Method Application, inputting the desired message in their RF communications device, which will signal the user when to send the percussive pulses. The rescue team can also effectively send messages to the trapped person by a Percussive Communications Method where each time the trapped person hears a percussive pulse burst they signal the reception of the burst, e. g. press a button, to their radio frequency communications device. The differential percussive pulse timings are then decoded by the percussive pulse rescue application and displayed as a message. In summary, the percussive pulse rescue system either makes it possible for a person trapped under overburden in possession of a radio frequency communications device 73 to communicate by this communications device or to send and receive percussive

pulse messages using a rescue application which runs on this communications device.

References Cited

United States Patent Documents

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Other Publications

Through-the-earth Electromagnetic Trapped Miner Location Systems. A Review Author(s): Pittman-WE, Church-RH, McLendon-JT;

Reference: Open File Report: 127-85, U.S. Department of the Interior, Bureau of Mines, 1985

The MINER Act of 2006 and Related NIOSH National Institute of Occupational Safety and Health Activities - Communications and Tracking 21 August 2007: http://www.cdc.gov/niosh/mining/mineract/communicationsandtr acking.htm