WO2000008405A2

WO2000008405A2 - Integrated laser frequency modulation tactical training helmet

Info

Publication number: WO2000008405A2
Application number: PCT/US1999/017813
Authority: WO
Inventors: Fritz W. Healey; Himanshu N. Parikh
Original assignee: Healey Fritz W; Parikh Himanshu N
Priority date: 1998-08-07
Filing date: 1999-08-03
Publication date: 2000-02-17
Also published as: AU1516100A; WO2000008405A3

Abstract

A tactical training helmet (TTH) for a laser based tactical engagement simulation training system. The TTH embodies decoder and processor circuitry (50), speakers (78) and sound effect and voice synthesis circuits (76) to provide real time sound effects and voice information to a soldier, and a GPS receiver (84) to dertermine the position of the soldier and receives the GPS position of a soldier/shooter from information transmitted over the soldier's/shooter's laser beam to determine the range of the soldier/shooter from a soldier/target to more accurately assess the likelihood of a 'Kill'. All laser detectors (118) are embodied in the TTH, and many face down toward the soldier's torso to detect secondary or scattered reflections of a soldier's/shooter's laser beam off of a soldier's/shooter's torso. Numerous other MILES functions are embodied in the TTH.

Description

INTEGRATED LASER FREQUENCY MODULATION TACTICAL TRAINING HELMET

Technical Field:

The present invention relates to a tactical training helmet (TTH) for use with multiple integrated laser engagement systems. Background Art: For over 25 years, armed services worldwide have been training soldiers and paramilitary personnel using multiple integrated laser engagement systems (MILES). MILES is a pulse-code-modulation optical communication system in which the communication medium is the atmosphere. A MILES laser transmitter generates an encoded message and transmits the encoded message through varying atmospheric conditions to a MILES receiver that is carried by a target and that decodes the message at the target to initiate required actions. The message generated by the transmitter must simulate weapon firing characteristics, round dispersion patterns and probability of hit as a function of range for specific weapon types. MILES has revolutionized the manner in which armies train for combat, and has become the standard against which all other tactical engagement simulation (TES) systems are measured. It is highly valued for its ability to accurately assess battle outcomes and to teach soldiers the skills required to survive in combat and destroy an enemy. With MILES, commanders at all levels can conduct opposing force free-play tactical engagement simulation training exercises that duplicate the lethality and stress of actual combat.

The MILES system uses laser bullets to simulate the lethality and realism of a modern tactical battlefield. Laser transmitters, mounted on a weapon and capable of shooting pulses of encoded infrared energy, simulate the effects of live ammunition. Detectors located on a target receive the encoded infrared energy transmitted upon firing a weapon. In the case of ground troops, the detectors are normally installed on webbing material that resembles a standard-issue load-carrying lift harness. Additional detectors may be attached to a web band that fits on standard- issue helmets. The arriving pulses that are sensed by detectors are amplified and compared to a threshold level. If the pulses exceed the threshold, that information is registered in detection logic. Once a proper arrangement of information exists, corresponding to a valid code for a particular weapon, the decoder decides whether the code is a near miss or a hit If a hit is registered, a hierarchy decision is then made to determine if the specific weapon can indeed cause a kill against the particular target and, if so, what the probability of a kill might be.

Conventional MILES soldier carried detection/ target systems consist of an array of optical detectors and electronics that are located on applique helmet and torso harnesses. These applique devices add from 6 to 20 pounds of additional weight for the soldier to carry during a training exercise. They limit the functionality of the soldier's tactical gear that is covered by the applique harness, and hinder his reactions in tactical situations. Also, conventional MILES detection systems are based on an array of silicon detectors, of which at least one must be directly illuminated by the shooter's transmitted laser beam with sufficient energy to exceed the preset threshold. This requires that a large array of detectors be distributed over the soldier's head and torso. If the laser beam happens to hit an area not covered by a detector, such as the neck, it is possible that the target would not respond. Further, the distribution of detectors all over the soldier's body requires that they be connected through wiring, making the system very sensitive to EMI and creating a complex and heavy harness. All known MILES training devices for man targets alert the soldier that he is under fire by providing a series of tones representative of near misses and kills. These tones do not accurately represent the sounds encountered during combat. Also, existing MILES detection systems compare the energy level of the shooter's laser pulses to a preset threshold to determine if the shooter is close enough to the target to be within the effective range of the shooter's weapon. However, because MILES is a pulse-code-modulation optical communication system in which the transmission medium is the atmosphere, the encoded message is inherently transmitted through and affected by varying atmospheric conditions. When received, the encoded message is decoded to initiate required actions. Ideally, the message as decoded accurately represents weapon firing characteristics, round dispersion patterns, and the probability of hit as a function of range for specific weapon systems. Unfortunately, the ability to accurately control the laser output power of the shooter to a precisely determined value relative to then existing atmospheric conditions, together with unpredictable atmospheric turbulence/ visibility variations that can and do frequently occur and cause the energy detected at the target detectors to vary significantly, results in unreasonable variations in the calculated effective range of a weapon.

Because MILES is a pulse code modulation optical communication system through the atmosphere, representative pairing between a soldier's/ shooter's MILES transmitter system and a soldier's/ target's MILES receiver system must be achieved by accurately setting weapon laser power and divergence and target detection sensitivity. Assumptions are made for typical atmospheric visibility and scintillation conditions. Range dependencies of PK's are achieved by an indirect method of dependence on the number of kill words received. The standard defining the MILES code structure contains weapon codes and player identification (PID) codes embedded in it. The present MILES code word structure does not allow the transmission of any additional information, due to pulse timing constraints. In consequence, only a limited amount of information can be encoded and transmitted, which reduces the fidelity of casualty assessments and provides an inadequate after- action-review. A need therefore exists for additional weapon type codes, PID codes and other characteristics to be transmitted to and decoded by MILES targets.

It would be desirable to improve the MILES system to enable transmission of additional information (e.g. GPS position/ location, range, elevation, lead angle, impact point of a projectile, etc.). This would greatly enhance the fidelity of hits and casualty assessments. The additional information transmitted and received would also provide for a vastly enhanced after action review and enable a soldier to better train for future missions. Further, the transmission of GPS position/ location would eliminate the need to carefully set and maintain the energy and sensitivity of associated laser transmitter and detection systems. Such an improved MILES system is disclosed in co-pending application entitled "Laser Frequency Modulation Tactical Training System," filed contemporaneously herewith as Serial No. , the teachings of which are specifically incorporated herein by reference.

Known laser based tactical engagement simulation training systems are disclosed by U.S. Patents No. 4,629,427, 4,662,845, 4,823,401 and 5,426,295, the teachings of which are specifically incorporated herein by reference.

An object of the present invention is to provide an improved laser based tactical engagement simulation training system.

Another object is to provide a tactical training helmet (TTH) for use in a laser based tactical engagement simulation training system. A further object is to provide a TTH for use in an improved MILES system that enables the transmission of an increased amount of information in a MILES code word.

Still another object is to provide a TTH for use in an improved MILES system that is downward compatible with a standard MILES system.

Disclosure of the Invention

In accordance with the present invention, there is provided a tactical training helmet (TTH) for being worn on the head of a user and for use in a laser based tactical engagement simulation training system in which an information containing laser beam is transmitted. The TTH comprises a helmet shell and means embodied in the shell for receiving the laser beam and for processing the information contained in the laser beam. The shell can comprise an outer shell and an inner shell contained within the outer shell, and the means for receiving and processing is carried by the inner shell. The means for receiving and processing can be carried on an outer surface of the inner shell between the inner and the outer shells. A GPS receiver is embodied in the shell for determining the position of the TTH. Information contained in the laser beam includes the GPS position of the source of beam, and the means for receiving and processing includes means for determining the distance between the GPS coordinates of the TTH and those of the source of the laser beam. The laser beam can represent a projectile fired by a weapon and contain information about the weapon, and the means for receiving and processing includes means responsive to the information about the weapon and the distance between the GPS coordinates of the TTH and those of the source of the laser beam for determining the effect of the projectile on the user. A motion sensor is embodied in the shell for sensing when the user is moving, and also embodied in the shell are means responsive to the motion sensor sensing that the user has moved at least a selected distance for activating the GPS receiver to obtain new position coordinates for the TTH. Batteries are carried by the shell for powering the various components, and also included and embodied in the shell are a long range RF antenna and a long range RF receiver for receiving transmitted GPS differential data for use by the GPS receiver to provide accurate coordinate positions for the TTH.

The means for receiving and processing includes laser detectors embodied in the shell. Some of the laser detectors face downward from the shell and detect secondary or scattered reflections of the laser beam off of the torso of the user. The means for receiving and for processing includes sound and voice synthesis means and speaker means for generating, based at least partly upon the information contained in the laser beam, real time sound effects of the projectile fired by the weapon and voice synthesized information identifying the type of weapon that fired the projectile.

For the situation where the user carries a weapon having a small arms transmitter (SAT) that has a short range RF transceiver, the TTH can include a short range RF antenna and short range RF transceiver embodied in the shell for accommodating communications between the SAT and the receiving and processing means. Should the SAT have an optical transceiver, the TTH can include a short range optical transceiver embodied in the shell for accommodating communications between the SAT and the receiving and processing means. To accommodate receiving and transmitting optical signals, there is a sealed optical window in the lower front of the outer shell to accommodate transmission of optical signals through the outer shell.

The outer shell of the TTH fits over the inner shell to cover and protect the means for receiving and processing. The shape of the outer shell replicates the shape of the outer surface of an actual tactical helmet, and the inner and outer shells are sealed and fastened together to form an assembly. All of the laser detectors are embodied in the shell, the shell has a lower circumferential lip, and the laser detectors are on and around the lip. The laser detectors have an optical acceptance angle that views the front, side and back of the user's torso.

A battery powers the various components embodied in the shell, including the means for receiving and processing, the motion sensor and the GPS receiver, and a power control means is embodied in the shell for powering down at least the GPS receiver when the motion sensor does not sense that the user is moving and for powering up the GPS receiver when the motion sensor senses that the user is moving, thereby to conserve battery power. To avoid unnecessarily powering up the GPS, the power control means powers up the GPS receiver only when the means responsive to the motion sensor senses that the user has moved at least the selected distance.

To accommodate external communications with the TTH, included are means embodied in the shell for communication with a PC, as well as means embodied in the shell for wireless downloading and uploading of data from and to an external source.

It is contemplated that the TTH be used in a laser based tactical engagement simulation training system that utilizes a code word structure characterized by a standard code word structure consisting of a plurality of bits of logic level "1" in selected positions with the remainder of the bits being of logic level "0", and in which the logic level "1" bits are FM modulated to have selected frequencies in order to embed additional information into the code word. The system can be a MILES system that generates a MILES code word having a standard MILES code word structure in which a predetermined number of bits are logic level "1" and are in bit positions selected to convey standard required information and in which the remaining bits are logic level "0", that modulates to selected frequencies individual ones of the logic level "1" bits of the standard MILES code word with each selected frequency having an assigned value so that the FM modulated MILES code word contains both the standard required information and information in addition to the standard required information, and that transmits the FM modulated MILES code word via the laser beam. In the latter case, the means for receiving and processing including means for decoding the FM modulated MILES code word received via the laser beam to obtain therefrom both the standard required and additional information. The foregoing and other objects, advantages and features of the invention will become apparent upon a consideration of the following detailed description, when taken in conjunction with the accompanying drawings. Brief Description of the Drawings

Fig. 1 shows the structure of a standard MILES code word; Fig. 2 shows an FM modulated MILES code word;

Fig. 3 shows the structure of an FM modulated code word in which GPS information is embedded;

Fig. 4 lists frequencies that can be embedded in an FM modulated code word and their assigned values; Figs. 5A-5F are signal waveforms illustrating the downward compatibility of the FM modulated MILES code word structure;

Figs. 6A-6F are signal waveforms illustrating the upward compatibility of the FM modulated MILES code word structure;

Fig. 7A is a block diagram of an encoder for generating FM modulated MILES laser code pulses; Fig. 7B is a table showing communication sequences between a SAT and a tactical training helmet (TTH) of the invention;

Fig. 7C is a table showing the various frequencies of FM modulated pulses of FM modulated MILES code words;

Fig. 8A is a block diagram of a decoder for receiving and processing FM modulated MILES laser code pulses;

Fig. 8B is a table showing the values assigned to a count generated by a frequency counter logic circuit of the encoder; Figs. 9A-9C are front, rear and side views, respectively, of a tactical training helmet (TTH) embodying the teachings of the present invention, and

Fig. 10 is a block diagram of a portion of the circuitry contained in the TTH of the invention.

Best Mode for Carrying out the Invention: Prior Art

Existing MILES is a pulse code modulation optical communication system through the atmosphere. Representative pairing between weapon and target systems is achieved by accurately setting weapon laser power and divergence and target detection sensitivity, with assumptions being made for typical atmospheric visibility and scintillation conditions. Range dependencies of weapons are achieved by an indirect method of dependence on the number of kill words received and information communicated is limited to weapon code and player identification (PID). Due to the limited number of codes available, each weapon code represents a group of similar weapons (e.g., code 27 represents all small arms: M16, M240, M60 and M249).

Fig. 1 shows the structure of a standard basic MILES code word. The requirements for an encoded MILES code word are defined in Standard for MILES communication Code Structure, MCC97 (PMT 90-S002B). That Standard defines the content and code structure for MILES codes and all variants of MILES, and applies to all MILES equipment and to all equipment having communication interface with any MILES equipment. The Standard requires that the basic MILES code structure consist of code words each having a unique and identified bit pattern. The basic MILES code word must be composed of eleven bits with a weight of 6 bits always equaling logic "1" and the remaining five bits always equaling logic "0" . The basic MILES code word identifier, that identifies to a receiver that the code word is a MILES code word, is the first three bit positions, and in all cases the identifier bit pattern must be "1 1 0". The basic MILES code bits are synchronized in time to the leading edge of the first bit of the basic MILES code word identifier, and the leading edges of two successive basic MILES code bit positions must occur at a 3 kHz +/- .015% rate (333 microsecond intervals). The time interval required to complete one basic MILES code word is 3.667 milliseconds.

The Standard calls for a MILES decode sampling scheme in which the time interval between successive basic MILES code word bits is divided into sixteen sampling BINS numbered by convention 1 to 16, with BLN 1 of each interval always being occupied by a basic MILES code bit (logic "0" or logic "1"). The MILES decode sampling rate is 48 kHz, sixteen times the 3 kHz bit position time slot generation rate. The result of the sampling is to divide the time between two successive basic MILES code word bits into sixteen sampling BINS, each being approximately 20.8 microseconds long. Every MILES system code word therefore consists of 176 decode sample BINS evenly distributed among the 11 basic MILES code word bits. The Standard MILES PID consists of the basic MILES code words specified in the Standard, interlaced with any one of the PID code bit patterns also specified in the Standard. The Standard MILES PID code word is composed of eleven bits with a weight of four bits always equaling logic "1" and the remaining equaling logic "0". Each PID number is uniquely assigned to a PID code bit pattern, and the PID code bits occur in sampling BIN number 6, 8 or 10.

The encoded MILES code word is transmitted via a laser of a small arms transmitter (SAT). The ability to successfully complete the transmission of the encoded message is significantly affected by the code word structure, message format, decoding method and threshold setting of the detector. Conversely, the ability to avoid false message reception is affected by the same factors. The functions of the MILES code are therefore to: (1) discriminate between weapon types with high reliability; (2) extend weapon simulator range in the presence of adverse atmospheric conditions; (3) reject random false signals; and (4) shape the kill zone profile vs. range to more accurately simulate weapon effectiveness. Known MILES encoding schemes are hard pressed to meet these requirements.

Conventional MILES soldier detection/ target systems consist of an array of optical detectors/ electronics that are located on applique helmet and torso harness's worn by a soldier. The applique helmet harness is applied to and carried by a conventional tactical helmet worn by the soldier, and the soldier on his torso wears the applique torso harness. These applique devices add from 6 to 20 pounds of additional weight to the soldier during a training exercise. They limit the functionality of the soldier's tactical gear that is covered by the applique harness and they limit his reactions in tactical situations.

The applique harnesses of conventional MILES systems include one or more audio buzzers to alert the soldier to occurring events and otherwise provide the soldier with information. However, while the sounds generated by the audio buzzers alert the soldier that he is under fire by means of a series of tones representative of near misses and kills, they do not accurately represent to the soldier the sounds that he would actually hear and encounter during combat.

Conventional MILES detection systems compare the energy level of a laser pulse fired or transmitted by a soldier/ shooter, as detected by a MILES receiver of a soldier/ target, to a preset threshold to determine if the shooter is within the effective range of his weapon. Control of laser output power of the shooter, as well as unpredictable atmospheric turbulence/ visibility variations, can and often do cause the energy level of the detected laser pulses to vary significantly, resulting in unreasonable variations in the calculated effective range of the shooter's weapon. Thus, the soldier/ target may receive an indication that he has been "killed", when in fact he has not been, and vice versa. Also, conventional MILES detection systems worn and carried by a soldier/ target are based on an array of silicon detectors, of which at least one must be directly illuminated by the shooter's laser beam with sufficient energy to exceed the preset threshold. This requires a large array of detectors distributed over the soldier's head and torso. If the shooter's laser beam happens to hit an area not covered by a detector, such as the neck, it is possible that the detection system of the soldier/ target may not respond and indicate a "hit" Also the distribution of detectors all over the soldier's head and torso requires that they be connected through wiring, making the system very sensitive to EMI as well as creating a complex and heavy harness.

The Invention The invention provides a tactical training helmet (TTH) that is compatible for use in either a conventional or an improved FM MILES system. The FM MILES system, with which the TTH is adapted for use, is disclosed in aforementioned co- pending application entitled "Laser Frequency Modulation Tactical Training System," filed contemporaneously herewith as Serial No. , the teachings of which have been specifically incorporated herein by reference. As described therein, the improvement provides a MILES code word structure that consists of a standard MILES code word in which additional information, over and above weapon identification and player identification (PID), is embedded. The FM MILES code structure provides for a large increase in weapon codes, PIDs and special characteristics/ data codes. The FM MILES code uses a combination of frequency modulation of the logic level "1" bits in a standard MILES code word and pulse modulation to transfer vast amounts of data in the same timeframe as standard MILES codes. Some examples of data which can be transmitted and decoded include GPS position, weapon lead angle, weapon elevation, time of flight, ammunition data etc. All the new codes are completely downward compatible and interoperable with conventional MILES systems. The invention integrates all of the conventional and additional MILES functions into a TTH that approximates the shape and weight of a corresponding tactical helmet. The TTH provides a soldier with protection during training that is similar to that provided by fiberglass helmet liners. The weight of the TTH is the same as the actual tactical helmet so that no additional weight is added to the soldier during training.

As compared with the simple tones provided by conventional MILES equipment, when used with the improved or FM MILES system, the TTH of the invention provides to a soldier real time sound effects of small arms ricochets, small arms bullets speeding by, large caliber explosions and other sounds as are customarily heard during combat. Also, voice synthesized information is provided to the soldier immediately after a sound effect to identify the type of weapon that was fired at and heard by the soldier, as well as its effect on the soldier. This serves to reinforce the training of the soldier to recognition of incoming projectiles/ explosions. The TTH incorporates a GPS receiver to determine the position of the soldier.

The GPS position of a shooter is embedded in an FM MILES code word and transmitted over the shooter's laser beam to the target When a target is "hit" by the shooter's laser beam it decodes the shooter's GPS position, determines its own GPS position, and then calculates the range between the shooter and target, and using an algorithm determines the probability of a "kill" based on the weapon type and actual range. This assures that the ballistics of the attacking weapon are accurately reflected even under adverse visibility, just as an actual bullet/ round would not be affected by visibility. Also, all of the laser detectors of the FM MILES receiver are mounted in a lower rim of the TTH. Some of the detectors face down toward the soldiers torso and detect the secondary or scattered reflections of the shooter's laser off of the target soldier's clothing and skin. This assures detection from all areas of the torso above the waist, including such areas as the neck and arms, as might be hit by the shooter's laser beam. Since all the detectors are in a small area (the TTH), more effective EMI shielding can be implemented. In the FM MILES system with which the TTH of the present invention is particularly adapted for use, and as described in said aforementioned application Serial No. entitled "Laser Frequency Modulation Tactical Training

System" and filed contemporaneously herewith, information over and above that required to be embodied in a standard MILES code word i.e., weapon type and player identification (PID), is embedded in the standard code structure for the word, in such manner as to maintain downward compatibility with existing MILES systems. In this connection, standard MILES code pulses comprise a basic MILES code word composed of 11 bits with a weight of 6 bits always equaling logic "1". The first 3 bits must be logic "1 1 0", which identify a MILES code word. The remaining 8 bits identify weapon type, and since they have a weight of 4 bits equaling logic "1", they can identify 36 weapon types. Leading edges of the bits occur at a 3 kHz rate, i.e., at 333 microsecond intervals, and time intervals between successive bits are each divided into 16 decode sampling BINS, with BLN 1 in each interval always being occupied by a basic MILES code bit (logic "1" or "0"). The sampling BINS occur at a 48 kHz rate, i.e., at 20.8 microsecond intervals, which is 16 times the 3 kHz bit generation rate. BINS 6, 8 and 10 are for containing player identification (PID) code, which is composed of 11 bits having a weight of 4 bits always equaling logic "1" and the remaining bits equaling logic "0". The standard MILES code word therefore has 176 sampling BINS numbered 1-16 between each code word bit, with BINS 1 always being occupied by a standard code word bit and BINS 6, 8 or 10 being occupied by PID bits. The MILES code word thus has a total weight of 10 bits always equaling logic level "1".

To embed additional information into the standard MILES code word, the logic level "1" word bits of the word are FM modulated. The normal MILES code bits, each of which consists of a single pulse, are replaced with two or more pulses at a selected frequency, during the same code pulse time frame. The particular frequency resulting from the FM modulation is determined by the time interval between the leading edges of the pulses that replace the standard single MILES code word pulse, according to the formula = 1/t . Fig. 2 shows the structure of an FM modulated MILES code word. There are a total of 10 pulse positions, i.e., bits of logic level "1", in the code word. By replacing each logic level "1" bit with pulses at a selected frequency, a significant amount of additional information can be embedded in and transmitted over the laser beam via the code word. Using just 10 unique frequencies, a total of 10¹⁰ numbers of data can be transmitted. Examples of data to be transmitted include GPS position, weapon range, elevation/ lead angle, impact point, etc. In the first pulse position, the single standard pulse has been FM modulated by being replaced by two pulses, the time interval between the leading edges of which is 3 μsec, representing a frequency of 333.33 kHz. Of the 10 bit/ pulse positions available in each MILES code word, the first is used to embed an identifier. The frequency embedded in the first position identifies the information embedded in the following 9 pulse positions. Fig. 3 shows an example of GPS position embedded into a MILES code word. Fig. 4 lists the embedded frequencies presently contemplated and their corresponding assigned values. Thus, to transmit a value of 357 in bit/ pulse positions 2, 3 and 4, the corresponding frequencies will be 400 kHz, 285.71 kHz and 222.22 kHz.

If, for example, "frequency 1" in the first bit/ pulse position of a MILES code word is used to indicate that GPS information follows, then that would indicate that the following 9 pulse positions of the code word contain GPS coordinate position data. For conveying GPS position data, each direction (X, Y and Z) may be allocated 3 of the 9 pulse positions. Using 10 different frequencies, each direction can be represented by a number from 0 to 999. The position transmitted by the soldier/ shooter is the difference between the present position of the transmitting system and a designated fixed reference point on a playing field. Position information may be transmitted in 11 meters resolution, with the transmitting system checking the remainder during division by 11 and incrementing or decrementing the quotient if the remainder is greater or less than 0.5. This results in a loss of only 5 meters accuracy in each direction. A MILES receiving system in a TTH of the soldier/ target that receives the code word decodes the word, extracts the position of the soldier/ shooter and multiplies the result by 11 (e.g. xl, yl, zl). The receiving system, which incorporates its own GPS sensor, then determines its position with respect to the designated reference point (e.g. x2, y2, z2), and then computes the range to the MILES transmitting system, i.e., to the soldier/ shooter, using the formula to compute distance between three-dimensional Cartesian coordinates f [ (xl-x2)² + (yl-y2)² + (zl-z2)² ]. Based on the distance to the target and the weapon code, the MILES receiving system of the soldier's/ target's TTH performs casualty assessments. Incorporating actual range as information specifically transmitted significantly enhances the fidelity of casualty assessments and provides for a very useful after-action review. The FM modulated MILES communication code word structure is downward compatible. A transmitted MILES code word that is embedded with additional information can be detected and decoded by a conventional MILES decoder, although information obtained from decoding will not include the information added, but only that which is in the basic MILES code word. In this configuration, the laser signal from an FM small arms transmitter (SAT) of the soldier/ shooter consists of a short series or burst of two or more pulses, at selected frequencies, placed in each standard MILES single bit locations where bits of logic level "1" occur. The series of FM pulses inserted in place of a conventional laser pulse are reduced in width and/ or adjusted in peak power so as to maintain the same average laser output energy as the single MILES laser pulse they replace. This is done to maintain downward compatibility with conventional MILES detectors, which integrate each incoming laser pulse and output a valid data bit if the energy of an incoming pulse is over a preset threshold. Fig. 5 A shows a conventional MILES laser pulse that may be sensed by a conventional MILES integrating detector, causing the detector to generate an output signal as shown in Fig. IB. The level of the detector output signal is compared to a preset threshold, and for as long as it is greater than the threshold, results in generation of a comparator output pulse as shown in Fig. 5C. The comparator output pulse, along with other such pulses that together make up a MILES word, are used for decoding the information contained in the word. Fig. 5D shows a bit of an FM modulated MILES code word in which additional information is embedded. When such an FM encoded bit is detected by a conventional MILES integrating detector, the pulses of the bit are integrated and result in a detector output signal, as shown in Fig. 5E. The level of the detector output signal is compared to a preset threshold, and for as long as it is greater than the threshold results in generation of a single comparator output pulse, as shown in Fig. 5F. The comparator output pulse, along with other such pulses that together make up a MILES code word, are used for decoding the information contained in the word and provide the same data fidelity as if the FM modulated signal were transmitted by an existing MILES transmitter. This process provides for FM modulated MILES code words to be downward compatible with existing or old MILES equipment.

The FM MILES code word structure also is upward compatible, such that an FM detection system that decodes an FM MILES code word can also decode a standard MILES code word, while maintaining the data fidelity provided by the respective SATs (not shown). Figs. 6A-6C illustrate the upward compatibility of the system. An conventional transmitted MILES code word pulse, shown in Fig. 6A, is received by a detector of the FM MILES receiver, which integrates the pulse and generates an output signal shown in Fig. 6B. If the detector output signal is above a preset threshold level, a comparator generates at its output a single short output pulse, as shown in Fig. 6C. The comparator output is applied to an FM decoder, which recognizes that there is only a single pulse and decodes the pulse as conventional MILES code, with its corresponding data fidelity.

Figs. 6D-6F illustrate some of the signals involved in receiving and decoding an FM modulated MILES code word. A detector receives an FM modulated laser pulse signal, shown in Fig. 6D, integrates the pulses of the laser signal and generates an output as shown in Fig. 6E. The detector output is applied to a comparator, and if it is above a preset threshold the comparator generates two short output pulses, shown in Fig. 6F. The comparator output is applied to an FM decoder, which recognizes that there are two individual pulses and decodes the pulses as being part of an FM MILES code word. This provides the enhanced data, such as GPS position, to the receiver system. Fig. 7A shows an encoder of a SAT, indicated generally at 20. The encoder is associated with a weapon and coupled to a TTH, and includes a blank detector circuit 22 that detects when a weapon is fired and generates a pulse that turns on a dc-dc converter 24, enables an oscillator control logic circuit 26, and informs a controller 28 that the weapon has been fired. The controller then generates appropriate MILES codes and outputs them to a pulse generator 30 and a laser driver 32. A battery 34 powers the SAT. To conserve battery, the oscillator control logic

26 is normally disabled. A pulse generated by the blank detector 22 or by a tickler circuit 36 momentarily turns on the oscillator, which enables the controller 28 to keep the oscillator and dc-dc converter 24 on for as long as necessary to process required operations. Pushing a button (not shown) on the SAT, to enable or disable a weapon, also turns on the oscillator.

To keep communications open between the SAT and a TTH worn by a soldier using the weapon with which the SAT is associated, the tickler circuit 36 turns on the oscillator 26 at controllable intervals. When the weapon is enabled, the tickler enables the oscillator every few seconds to communicate different events, as shown in Fig. 7B, to the soldier via speakers in the TTH. If the SAT receives a "kill" message, the tickler switches the oscillator turn-on intervals from a few seconds to a few minutes to conserve battery power.

Energy stored in a capacitor (not shown) powers the system when the dc-dc converter 24 is disabled. As capacitor energy decreases, circuit voltage VCC, normally output from the converter 24, decreases. When the voltage VCC drops below a selected threshold, a VCC monitor 38 turns on the converter to recharge the capacitor, and then turns off the converter when VCC increases to above the threshold.

The dc-dc converter 24 increases battery voltage to a higher voltage required for the voltage VCC and to power a laser diode 40. Since a charged-capacitor powers the system when the system is inactive, the converter normally is off. However, when the tickler 36 is activated, the weapon is fired, or a button on the SAT is pushed to enable or disable the weapon, the converter is turned on, since the system is now active and requires more power. The converter also monitors battery voltage and generates and sends to the controller 28 a "low battery" signal.

The pulse generator 30 embeds additional information into the standard MILES code word by converting each standard MILES code logic "1" bit received from the controller 28 into a set of two pulses. The space or time interval between leading edges of the two pulses represents the frequency of the FM modulated pulse according to the equation / = l/t, and is assigned a value. The particular value or frequency of the pulse is controlled by a 4-bit input from the controller, as shown in Fig. 7C, which presently are used to encode 10 different frequencies, but if desired could be used to encode more. The output from the pulse generator is applied as an input to the laser driver 32, which is a high speed, high current pulse driver that provides constant power/ energy for each laser pulse output by the laser diode 40. The laser diode generates a pulsed optical laser beam output in response to inputs from the laser driver and at the pulse spacing defined by the controller. The laser beam is aimed by a soldier/ shooter at a MILES equipped target, such as a TTH worn by a soldier/ target, and when the blank detector 22 senses the firing of a blank, the optical code sequence is sent out, received and decoded by the target and assessed accordingly.

Radio frequency (RF) communication between the SAT and TTH, carried and worn by a soldier, is always initiated by the SAT. Whenever the oscillator 26 is enabled, the controller 28 generates a "hello" message and sends it serially to an RF transmitter 42, which applies it to a transmit (TX) antenna 44 that radiates it into the atmosphere to initiate communications with the TTH.

A radio frequency (RF) receiver 46 obtains signals from a receive (RX) antenna 48 that collects RF signals from the atmosphere. The RF receiver couples the signals to the controller 28 for processing. The RF receiver detects and sends to the controller only those signals that are of the frequency transmitted by the TTH. Since the SAT always initiates communications, power to the RF receiver normally is turned off to conserve battery. Power to the RF receiver is enabled when the SAT initiates communications with the TTH and is disabled when it receives a "communications over" message. Power to the RF receiver also is disabled if there is no response from the TTH for a specified time. The TX and RX antennas 44 and 48 are used to transmit and receive RF data. Since RF communications between the SAT and TTH take place in a very short range, the antennas do not have to be high quality. For this reason, they may economically and conveniently be printed directly on the circuit board for the encoder.

The controller 28 provides all processing and signal generating functions for the system. The controller generates both MILES code words and the frequency selection bits that control the pulse generator 30 to FM modulate the standard MILES code word to embed therein additional information to be transmitted by the laser, such for example as GPS position. The controller also processes RF messages that are to be transmitted and that are received, and further handles power management, blank fire detection interrupts and built-in-testing.

Fig. 8A shows a decoder, indicated generally at 50, that is associated with and incorporated into a TTH as provided by the invention. The decoder is powered by lightweight and replaceable disposable or rechargeable battery packs 51 and includes a detectors/ amplifier circuit 52 that has laser detectors located in the TTH, which detectors have a low capacitance and a very fast response time. The detectors sense both existing MILES code laser pulses and FM MILES code laser pulses, and a fast pulse amplifier of the circuit uses a signal from the detectors to generate pulses at a level required by the decoder system. The high speed of the detectors/ amplifier is required to respond to the FM modulated MILES code word structure, which has an increased pulse rate in that each standard MILES code word bit is replaced by at least two pulses. However, the circuit can also process conventional MILES code laser pulses. The detectors are further used as the receiving end of weapons that use a short-range optical link for communications. In response to received laser pulses, an output from the detectors/ amplifier 52 enables a 10 MHz frequency counter logic circuit 54 and is applied to an integrator 56. If an FM MILES code word is being received, pairs of pulses replace each standard MILES code pulse, and the first pulse of each pair enables the 10 MHz oscillator and the second pulse disables the oscillator, so that the frequency counter logic circuit counts the number of pulses generated by the oscillator while it is enabled. If a standard MILES code word is received there are no pairs of pulses, in which case the oscillator is automatically disabled after a specific time by a latch/clear counter pulse, by which time a count of about 100 has been generated. This maximum count of about 100 is used to differentiate between the standard MILES and the FM MILES code structures. The latch/ clear counter pulse is also used to latch a count for a processor 58 and to clear the frequency counter logic circuit and prepare it for the next MILES code pulse, or set of two pulses for FM MILES. The magnitude of the count generated by the frequency counter logic circuit for FM MILES code pulses depends on the width or time interval between the leading edges of the two pulses. Fig. 8B shows the value assigned to each count.

The integrator 56 integrates incoming pulses from the detectors/ amplifier 52. Whether it receives a single pulse, as in conventional MILES, or a set of two or more pulses, as in FM MILES, the integrator will output a single pulse of the same pulse width. Trailing edges of the integrated pulses cause an integrated pulses logic circuit 60 to generate a latch/ clear counter output that disables the 10 MHz frequency counter logic circuit 54, thereby stopping the count when only one pulse is received, as in conventional MILES. The same trailing edge also generates a second pulse that latches the count and is applied as an input to a non-maskable interrupt (NMI) logic circuit 62, in response to which the NMI logic circuit generates a NMI signal to bring the processor 58 out of a power-down mode. After the count is latched and the processor activated to read and process the count, the trailing edge of the second pulse clears the frequency counter logic circuit to prepare it for the next MILES code pulse. Integrated MILES code pulses are also input to a synchronizer 64 that receives an output from a 96 kHz oscillator 66 and aligns the integrated pulses with the oscillator output. This is essential since the MILES code pulses need to be aligned with the oscillator output so that the processor 58 can read and decode them as they are being clocked through a shift register 68. The output from the oscillator 66 also is applied directly to the Tl input of the processor 58, to the shift register and to a BINS counter logic circuit 70. The 96 kHz signal going to the synchronizer, shift register and BINS counter logic circuit is normally disabled to reduce power consumption, and is enabled by pulses output from the detectors/ amplifier circuit 52. After processing of MILES code pulses is completed and there are no further incoming pulses, to conserve battery power the processor disables the 96 kHz oscillator.

When the 96 kHz oscillator 66 is enabled, the shift register 68 serially shifts synchronized MILES code pulses through 352 bit positions at a 96 kHz rate. The shift register has 11 outputs that are spaced 32 bits apart to correspond to the bit spacing in a MILES code word of 333.3 μsec. When a MILES code word is shifted into the shift register, the first three bits (1 1 0) indicating the occurrence of a MILES code word are detected by a MILES code detector 72, which generates an output pulse to reset the BINS counter logic circuit 70, to latch the MILES word in the shift register and to interrupt the processor 58 so that it can read and evaluate the latched 11-bit MILES word. Resetting the BINS counter logic circuit also starts the circuit so that BINS 6, 8 and 10 of the MILES word can be processed. While the 96 kHz oscillator 66 is enabled, the BINS counter logic constantly counts, with the count being reset to zero when the MILES code detector is activated. Since there are 32 shift register bits and 16 bins in each MILES code bit, it takes a count of 2 for each BIN shifting. Therefore, when the BINS counter logic circuit reaches counts of 12, 16 and 20, the shift register is latched for bins 6, 8 and 10 of the MILES word. These BIN outputs are coupled to the processor so that it will know that the latched BINS are ready for reading and processing. An up/ down noise counter 74 counts up whenever a MILES code word pulse enters the shift register 68 and down whenever a pulse is shifted out. When a complete MILES word has been shifted into the shift register, if there is no noise the count is 10, since a MILES word with weapon and PID information includes 10 bits. Because of EMI and other noise sources, there can be a count greater than 10. To maintain fidelity, a noise threshold can therefore be set, so that if the noise count is above the threshold, the MILES word will not be processed.

The TTH uses synthesized voice and sound effects to let the user know in real time what events are happening. When an event occurs, the processor 58 evaluates the event and sets the control and address lines of a voice/ sound logic circuit 76 to activate an appropriate voice or sound effect. The voice and sound effects are stored in specific address locations on the voice/ sound logic circuit, so that they can be accessed individually. The voice and sound effects are amplified before being output to speakers 78. The voice/ sound logic circuit also has volume adjustment and a power-down mode for power conservation when inactive. Some of the events that can activate a voice or sound effect include power on, user switches pressed, kill or near miss, low battery, weapon enabled/ disabled, etc.

The GPS consumes considerable energy. To conserve battery power by powering down the GPS when the user of the TTH is not moving, the decoder includes a motion sensor 80 that generates a signal, when the user is walking or running, to activate the processor 58 from a power-down mode. The processor then turns on the GPS and gets new position information via a GPS antenna 82 that detects signals from GPS satellites and applies the signals to a GPS receiver 84 for processing. The GPS receiver generates position information that is serially transmitted to the processor. The GPS receiver is equipped with a second serial channel to receive differential corrections from an optional differential receiver.

Differential corrections may be necessary because the position information received from GPS satellites is frequently and intentionally degraded by the use of selective availability. The GPS receiver is turned off after the processor receives new GPS position information. The TTH has a serial debug channel for connection directly to the RS-232 port of a PC, and the decoder therefore includes a debug logic circuit 86 for converting the RS-232 signals from the PC into TTL signals that can be received and processed by the processor 58. The debug channel is necessary in order to run the system directly from a PC for the purpose of software debugging. An infrared light emitting diode (IR LED) of an infrared transmit (IR TX) logic circuit 87 is used to communicate with existing weapons that use an optical link. The processor 58 serially transmits information using its serial channel 0 for serial data and timer 0 for reducing the width of serial data pulses. The detectors/ amplifier 52 is used as the receiving end of this optical communications channel.

An RF transmitter 88 in the TTH is used to respond to messages by the SAT. Whenever a request for "weapon enable" or a "hello" message is received, the processor 58 generates a response and sends it to the RF transmitter. The message flows serially from the RF transmitter to a TX antenna 90, from which it is radiated into the atmosphere to initiate communications with the SAT. The RF transmitter operates at the same frequency as the RF receiver 46 of the SAT, and is also used to transmit data to a PC for after action review (AAR).

An RF receiver 92, which operates at the same frequency as the SAT's RF transmitter 42, obtains signals from an RX antenna 94 and couples those signals serially to the processor 58. Messages from a PC or SAT are received and processed and a response is generated and sent out through the RF transmitter. A receiver power logic circuit 96 controls power consumption of the RF receiver. To conserve battery, the RF receiver is turned on only for brief periods to look for PC or SAT RF messages, but stays powered-up continuously as long as a message is being received. When the receiver power logic circuit detects that a message no longer is being received, power to the RF receiver goes back to being enabled for only brief periods.

The TX and RX antennas 90 and 94 are used to transmit and receive RF data. RF communications between the SAT and TTH take place in a very short range, since the same soldier who wears the TTH also carries the weapon to which the SAT is attached. The antennas therefore do not have to be high quality, and are conveniently and economically printed directly on the decoder circuit board.

A serial 0 select logic circuit 98 is used to multiplex two serial channels into one. This is necessary since the processor 58 only provides two serial channels. To select the data that will be transmitted or received, the processor sends a select signal to the serial 0 select logic circuit to cause it to receive the selected serial channel. The serial 0 select logic circuit is used to select between the IR and RF serial channels. A serial 1 select logic circuit 99 is used to select between the GPS and debug serial channels.

Whenever a switch on the TTH is pressed, the NMI logic circuit 62 generates a pulse to awaken the processor 58 from its power-down state. Another interrupt is generated by a switch controls logic circuit 100 to let the processor know that a switch has been pressed. The processor then generates a signal to latch the switch data and process the switch that was pressed. Switches on the TTH that are available for use include (1) an "events" switch, used to replay events starting from the last one; (2) a "volume" switch, used to adjust the volume of the speakers; (3) a "bit" switch, used to perform a built-in test, and (4) a "spare" switch, used to enable existing SAT's. A power logic circuit 102 incorporates a comparator to detect for low battery and a dc-dc converter that generates two different voltages and a shutdown (SHDN) signal. A low battery signal is generated when the voltage of the battery 51 falls below a specific threshold. The signal is processed when a switch is pressed, and a voice event is then generated to let the user know that battery power is low. The dc- dc converter uses battery power to generate the VCC voltage for the decoder system. The SHDN signal generated by the dc-dc converter is used to detect when battery power is lost as a result of switching the power off or removing the batteries. Because of the high speed of the decoder system 50, a shutdown event can be processed and recorded before power is completely lost. A VCC monitor 104 detects when the VCC supply voltage declines below a preset threshold. When this occurs, a reset signal is and continues to be asserted for at least 140 msec, after VCC has again risen above the preset threshold. This signal is used as a reset for the processor 58 and is usually applied at power-on to allow system power (VCC) to be fully charged. The processor 58 is clocked by a 24.576 MHz oscillator and is normally in a power-down state to conserve battery power. To activate the processor, the NMI logic circuit 62 receives signals from various sources in the system and generates an NMI signal that is sent directly to the processor's NMI input. Another signal is normally generated to let the processor know what it was awakened by. The various sources used to generate an NMI signal include the motion sensor 80, the switch controls logic circuit 100, the power logic circuit 102 in a SHDN event, the integrated laser pulses logic circuit 60, and the RF receiver 92.

Figs. 9A-9C show a MILES tactical training helmet (TTH), indicated generally at 110, embodying the teachings of the invention. The TTH has all of the standard and all of the aforementioned FM MILES related detection functions integrated into a replica of a conventional actual tactical helmet as would be worn by a soldier in combat. The weight and shape of the TTH matches that of the actual tactical helmet it replicates, so that no additional weight or other constraints are imposed on the soldier/ wearer. The TTH 110 has an inner shell 112 that serves as the main mounting structure to which all the components and subassemblies of the FM MILES receiver are attached, including the decoder 50. The inner shell is constructed of a rigid material such as composites, fiberglass, thermoplastics or metals, and is made to a shape that replicates the shape of the inner surface of an actual tactical helmet. A head suspension band 114 and a chinstrap 116 are attached to the inner surface of the inner shell in the same locations as they would be on an actual tactical helmet. Included among the major components of the FM MILES receiver/ decoder attached to the outer surface of the TTH inner shell 112, and some of which are shown in the Fig. 8A block diagram of the decoder 50, are the headset speakers 78, the GPS antenna 82 and the replaceable rechargeable batteries 51. Further included are optical detectors 118 that generate inputs for the fast pulse amplifier 52 and an FM decoder 119, user switches 120, a long range RF antenna 122, a short range RF antenna 124, the short range optical emitter or transmitter 126, a motion sensor 128 that provides an input to the motion sensor circuit 80, and electronic circuit cards 130 that include the electronic components of the decoder 50.

The electronic circuit cards 130 consist of a group of functional circuits such as MILES decoding, processing, RF transceivers, amplifiers and power conversion circuits, etc., which are on separate circuit card assemblies (CCAs) and are interconnected using wire/ flex wire. Alternatively, a flex circuit can be made to provide all or most of the circuits in a single unit for ease of installation over the profile of the inner shell 112 of the TTH 110. Semi-rigid formed CCAs, as well as hybrid and multi-chip modules (MCM) chip technology, may all be employed to minimize the size of the circuits, thereby allowing easy attachment of the circuits to the curved surface of the inner shell. An outer shell 132 of the TTH 110 fits over the inner shell 112 to cover, seal and protect all the components attached to the inner shell. The outer shell is constructed of a rigid material such as composites, fiberglass, thermoplastics, or metals. The shape of the outer shell replicates the shape of the outer surface of an actual tactical helmet. A sealed optical window 134 is incorporated into the lower front of the outer shell and accommodates transmission of optical signals through the outer shell. A series of shock absorption devices 136, made from foam or elastomer materials, are mounted between the inner shell and the outer shell. The outer and inner shells are joined and sealed together to form an assembly by means gasket 138 attached to the outer circumference of the inner shell and retained against the inner circumference of the outer shell by a series of fasteners 140 installed around the circumference of the outer shell.

As compared with a conventional MILES system, in which optical detectors are located on both a soldier's helmet and torso, the invention contemplates that all of the optical detectors be located on the TTH 110. To this end, a series of sensitive optical detectors 118 are located circumferentially around a lower lip of the inner shell 112, as shown in Fig. 9C. These detectors have an optical acceptance angle that views the front, side and the back of the soldier's torso/head. When a laser "bullet" is fired at the soldier and impacts on his body_/ some of the light is dispersed up toward the helmet where it is detected. This eliminates the need for placement of additional optical detectors on the soldier's torso/body. It also eliminates the sun from directly impacting the detectors, reducing the adverse noise generated by high levels of sunlight relative to the low levels of the optical laser bullet This improves signal to noise level reduces the false bit rate and improves the probability of a successful laser pairing. The sensitive optical detectors used in the TTH 110 device have low capacitance and are fast. The fast pulse amplifier 52 used with these detectors responds to both the conventional MILES code structure as well as the FM MILES code structure. The detection system also provides the receiving functions of the duplex short range optical handshaking for weapons and data exchange devices employing a short range optical link.

Except for the electronics contained in the SAT attached to the weapon, all of the other electronics for the MILES system carried by a soldier, including the decoder 50, are contained in the TTH 110. Fig. 10 shows a block diagram of some of the more salient electronic components contained in the TTH, some of which have already been discussed in connection with the decoder.

A complete GPS system, including the GPS antenna 82 and the GPS receiver 84, is integrated into the TTH 110 to provide positional data to the TTH electronics. The GPS antenna picks up RF signals from a satellite, and the GPS receiver processes the signals. Differential corrections may be provided to the GPS receiver by either short range or long range data links, via a differential correction circuit 144, to improve positional accuracy. This positional data is used, in conjunction with the shooter position as decoded from FM MILES code transmitted via the shooter's laser beam, to determine the actual range between the shooter and the TTH/ target. If the range is within the effective limits of the weapon, then the system uses an algorithm to assess the appropriate kill/ miss response routine with corresponding sound effects and synthesized voice information being provided to the soldier/ target. All soldiers normally wear a TTH 110, and each soldier may be both a shooter and a target. Using information obtained from the GPS unit, the TTH transfers its present position to the soldier's weapon over a short range data link. The soldier's weapon, when fired, transmits the shooter's position over the laser beam using the FM MILES code structure.

The motion sensor 128 and its circuit 80 are in the TTH 110 and used to sense and interpret sharp vertical movements generated when the soldier's foot impacts the ground during walking or running. The motion sensor is immune to slow changes, such as head rotation or tilting. The signal generated by the motion sensor is processed by the processor 58, to determine the number of steps taken by the soldier. When the number exceeds a preset threshold, the microprocessor turns on GPS power and obtains the new GPS position of the soldier who is now moving. Since the GPS unit is the major power consuming device in the system, control over GPS unit activation dramatically reduces the overall power consumption, making battery operation feasible.

The soldier is warned of a low battery condition by voice synthesis through the headset speakers 78 in the TTH, which are controlled by the voice/ sound logic circuit 76 that includes a sound and voice synthesis circuit 148 and an audio amplifier 150. Another function served by voice synthesis occurs whenever the laser detectors 118, 52 receive a valid message and the decoder 50 assesses a weapon near miss or kill, in which case a corresponding sound effect that simulates the actual sound of that incoming round is generated. This reinforces the soldier's awareness and knowledge of the different tactical combat sounds. The sound effect is immediately followed by a voice synthesis generated message describing the nature or significance of the sound effect and the ultimate effect on the soldier (kill, miss, hit etc). Other voice synthesis housekeeping messages are also generated and presented to the soldier as required (e.g. resurrect, reset, BIT fail, low battery etc.). Various inputs to the processor 58, such as from a long range data link comprising the long range antenna 122, a long range receive circuit 154 and a long range transmit circuit 156; from a short range data link comprising the short range antenna 124, a short range receive circuit 160 and a short range transmit circuit 162; from the operator switches 120; and from the optical detection circuit 52; etc., result in generation of sound effects/ voice synthesis. Sound effects of weapon explosions (artiUery, nuclear, mines etc.) resulting from the processing of data from a long range simulated area weapon effects (SAWE), combat maneuver training center (CMTC), national training center (NIC), precision range integrated maneuver exercise (PRIME), etc., or from the short range data link are also provided.

The long range data link is an RF data link which can be bi-directional (NIC, CMTC, joint readiness training center (JRTC), PRIME, etc.) or receive only SAWE. Integration of the long range data link into the helmet places the corresponding antenna 122 at a high point on the soldier, providing the best RF coverage. The long range data link also receives the transmitted GPS differential data, which is used by the GPS receiver 84 to provide accurate position location. The short range data link can be a low power RF link, optical link or a combination of the two. This link is the primary link that the TTH 110 and the soldier's SAT use to exchange data. Types of data exchanged include weapon status, firing events, GPS position and weapon disablement. The short range data link also provides the primary interface between the data collection device and the TTH. Data exchanged includes such things as time, events from an event storage memory 164 which are time-stamped using a real time clock 147, system status, etc.

The invention therefore provides a TTH 110 for a MILES system, which is adapted for use with either a standard MILES system or an FM MILES system as described in said aforementioned co-pending application. All subsystem components of the TTH are integrated into a single assembly. The shape of the TTH closely replicates the conventional tactical Kevlar tactical helmet, and the weight of the TTH, including batteries, is identical to the conventional Kevlar helmet. The net effect is that no extra weight or physical limitations are placed on the soldier when the soldier uses TTH instead of a conventional Kevlar helmet during training exercises. Also, with all the components of the MILES detection system integrated into the helmet, the soldier is free to use the type of garments normally employed, such as the "H" harness, light forces vest, body armor, cold weather clothing or rain gear. Since the detection system looks for cumulative laser energy from the soldier's body, the soldier is rewarded with a lower probability of being hit when in the prone position or in a foxhole.

The TTH 110 does not have any exposed wiring, webbing or protruding detectors, which it is anticipated will result in about an 80% reduction in maintenance costs. Also, since the TTH reduces the MILES detection system from two assemblies (one applique harness for the tactical helmet and the other for the torso) to one, it is expected that the result will be an additional reduction in spare parts costs, inventory and repairs.

The TTH provides for accurate MILES decoding and casualty assessments. All detectors are mounted within the TTH, which provides improved immunity to EMI due to helmet shielding and short detector wire lengths. The detectors respond to the fast FM encoded laser pulses as well as to current MILES laser pulses. The detectors are located on the lower rim of the helmet, looking down at the head/ torso of the soldier, so that they pick up scattered laser energy impacting the soldier. As a result, sun noise affects the detectors less, since the detectors do not directly view the sun. The TTH 110 provides for non-contact data downloading for after action review. The TTH also provides audio cues (voice synthesis and sound effects) which simulate realistic sounds of explosion, small arms impacts, ricochets etc. The voice synthesis message that occurs immediately after the sound effect identifies the nature of the sound and thereby reinforces the soldier's recognition of the sound. Voice synthesis further provides BIT, administrative and medical messages. No display is required due to use of voice synthesis. A membrane switch panel allows the audio messages to be selectively played for BIT, administrative, medical and event review.

The short range data link transfers GPS position to the SAT of the soldier's weapon for transmission over the laser beam. It enables/ disables the weapon and exchanges PID and weapon fire events. It allows non-contact data downloading and uploading, and provides the option to use either an RF or optical transfer medium. It is expandable to allow receipt of messages from future developed devices such as mines, grenades, collateral kill repeaters, etc. The power supply and management system uses rechargeable and replaceable lithium batteries for power. An integral motion sensor determines whether the soldier is changing his position such that updated GPS position information is required, and when movement is not being detected controls application of power to the GPS to maximize battery life and therefore the time between battery charging. All electronics are powered from dc-dc converters that have 85-90% efficiency.

The GPS system incorporated into the TTH provides information that enhances the fidelity of casualty assessments and after action review. The GPS system can have a range data transceiver for lightweight player detection device (PDD) applications, and receives indirect fire impact events such as chemical, artillery, mortars, nuclear, mines, etc. It receives GPS differential correction data as well as housekeeping commands such as built in test (BIT) request, reset and playing field reference point. It transmits near real-time player events and player position to the network command center. The TTH design accommodates future growth to meet changing needs. The internal system architecture allows for reasonable expansion. For example, a magnetic compass can be added to determine the direction the soldier was looking at the time he was hit by a shooter, and various visual displays/ cues can be added to give the soldier an indication of impact locations of indirect weapons. Ultrasonic transducers can be used to enable position location within military operations on urbanized terrain (MOUT) facilities.

While embodiments of the invention has been described in detail, various modifications and other embodiments thereof can be devised by one skilled in the art without departing from the spirit and scope of the invention, as defined in the accompanying claims.

Claims

Claims:

1. A tactical training helmet (TTH) for being worn on the head of a user and for use in a laser based tactical engagement simulation training system in which an information containing laser beam is transmitted, said TTH comprising a helmet shell; and means embodied in said shell for receiving the laser beam and for processing the information contained in the laser beam.

2. A TTH as in claim 1, wherein said helmet shell comprises an outer shell and an inner shell contained within said outer shell, said means for receiving and processing being carried by said inner shell.

3. A TTH as in claim 2, wherein said means for receiving and processing is carried on an outer surface of said inner shell between said inner and said outer shells.

4. A TTH as in claim 1, further comprising a GPS receiver embodied in said shell for determining the position of the TTH, wherein information contained in the laser beam includes the GPS position of the source of beam, and said means for receiving and processing includes means for determining the distance between the GPS coordinates of the TTH and those of the source of the laser beam.

5. A TTH as in claim 4, wherein the laser beam represents a projectile fired by a weapon and contains information about the weapon, and said means for receiving and processing includes means responsive to the information about the weapon and the distance between the GPS coordinates of the TTH and those of the source of the laser beam for determining the effect of the projectile upon the user.

6. A TTH as in claim 1, wherein said means for receiving and processing includes laser detectors embodied in said shell.

7. A TTH as in claim 6, wherein some of said laser detectors face downward from said shell and detect secondary or scattered reflections of the laser beam off of the torso of the user.

8. A TTH as in claim 5, wherein said means for receiving and for processing includes sound and voice synthesis means and speaker means for generating, based at least partly upon the information contained in the laser beam, real time sound effects of the projectile fired by the weapon and voice synthesized information identifying the type of weapon that fired the projectile.

9. A TTH as in claim 1, wherein the information contained in the laser beam is encoded and said means for receiving and for processing includes a decoder for the information.

10. A TTH as in claim 4, including a motion sensor embodied in said shell for sensing when the user is moving, and means embodied in said shell and responsive to said motion sensor sensing that the user has moved at least a selected distance for activating said GPS receiver to obtain new position coordinates for said TTH.

11. A TTH as in claim 1, including batteries carried by said shell for powering said means for receiving and processing.

12. A TTH as in claim 4, including a long range RF antenna and a long range RF receiver means embodied in said shell for receiving transmitted GPS differential data for use by said GPS receiver to provide accurate coordinate positions for said TTH.

13. A TTH as in claim 1, wherein the user carries a weapon having a small arms transmitter (SAT) that has a short range RF transceiver, and including a short range RF antenna and short range RF transceiver means embodied in said shell for accommodating communications between the SAT and said receiving and processing means.

14. A TTH as in claim 1, wherein the user carries a weapon having a small arms transmitter (SAT) that has an optical transceiver, and including a short range optical transceiver embodied in said shell for accommodating communications between the SAT and said receiving and processing means.

15. A TTH as in claim 14, including a sealed optical window in the lower front of said outer shell to accommodate transmission of optical signals through said outer shell.

16. A TTH as in claim 3, wherein said outer shell fits over said inner shell to cover and protect said means for receiving and processing, the shape of said outer shell replicates the shape of the outer surface of an actual tactical helmet, and said inner and outer shells are sealed and fastened together.

17. A TTH as in claim 6, wherein all of said laser detectors are embodied in said shell.

18. A TTH as in claim 6, wherein said shell has a lower circumferential lip and said laser detectors are on and around said lip.

19. A TTH as in claim 6, wherein said laser detectors have an optical acceptance angle that views the front, side and back of the user's torso.

20. A TTH as in claim 1, including short range optical transceiver means embodied in said shell for communicating with weapons and data exchange devices employing a short range optical link.

21. A TTH as in claim 10, including a battery for powering said means for receiving and processing, said motion sensor and said GPS receiver, and power control means embodied in said shell for powering down said GPS receiver when said motion sensor does not sense that the user is moving and for powering up said GPS receiver when said motion sensor senses that the user is moving, thereby to conserve battery power.

22. A TTH as in claim 21, wherein said power control means powers up said GPS receiver when said means responsive to said motion sensor senses that the user has moved at least said selected distance.

23. A TTH as in claim 1, including means embodied in said shell for communication with a PC.

24. A TTH as in claim 1, including means embodied in said shell for wireless downloading and uploading of data from and to an external source.

25. A TTH as in claim 1, wherein said TTH is for use in a laser based tactical engagement simulation training system that utilizes a code word structure characterized by a standard code word structure that consists of a plurality of bits of logic level "1" in selected positions with the remainder of the bits being of logic level "0", and in which the logic level "V" bits are FM modulated to have selected frequencies in order to embed additional information into the code word.

26. A TTH as in claim 1, wherein said TTH is for use in MILES systems that utilize a code word in which FM modulated pulses of selected frequencies replace individual bits of logic level "1" in a standard MILES code word.

27. A TTH as in claim 1, wherein said TTH is for use in a MILES system utilizing a code word structure in which individual ones of the bits of logic level "1" are FM modulated to have selected frequencies.

28. A TTH as in claim 1, wherein said TTH is for use in a MILES system that generates a MILES code word having a standard MILES code word structure in which a predetermined number of bits are logic level "1" and are in bit positions selected to convey standard required information and in which the remaining bits are logic level "0", that modulates to selected frequencies individual ones of the logic level "1" bits of the standard MILES code word with each selected frequency having an assigned value so that the FM modulated MILES code word contains both the standard required information and information in addition to said standard required information, and that transmits the FM modulated MILES code word via the laser beam, said means for receiving and processing including means for decoding the FM modulated MILES code word received via the laser beam to obtain therefrom both the standard required and additional information.

29. A TTH as in claim 1, wherein said TTH is for use in a MILES system that generates a standard MILES code word in which a predetermined number of bits are logic level "1" and are in bit positions selected to convey standard required information and in which the remaining bits are of logic level "0", that embeds additional information in individual ones of the logic level "1" bits to generate a code word containing both the standard required information and the additional information, and that transmits the code word containing the additional information via the laser beam, said means for receiving and processing including means for decoding the code word received via the laser beam to obtain therefrom both the standard required and additional information.

31. A tactical training helmet (TTH) for being worn on the head of a user and for use in a laser based tactical engagement simulation training system, said TTH comprising a helmet shell; a GPS receiver embodied in said shell for determining the position of the TTH; means, embodied in said shell, for receiving, processing and decoding information contained in an incoming laser beam, which information includes an identification of the GPS position of the source of the laser beam; and means, embodied in said shell, for determining the distance between the GPS coordinates of the TTH and those of the source of the laser beam.

32. A TTH as in claim 31, wherein the incoming laser beam represents a projectile fired by a weapon and contains information about the weapon, and said TTH further includes means, embodied in said shell, for determining the effect of the projectile on the user based upon the information about the weapon and the distance between the GPS coordinates of the TTH and those of the source of the laser beam.

33. A TTH as in claim 31, wherein said means for receiving, processing and decoding information includes laser detectors embodied in said shell.

34. A TTH as in claim 33, wherein said shell is worn by a user and some of said laser detectors face downward from said shell and detect secondary or scattered reflections of the laser beam off of the torso of the user.

35. A TTH as in claim 32, wherein said shell further embodies sound and voice synthesis means and speaker means for generating, based upon the information contained in the incoming laser beam, real time sound effects of the projectile fired by the weapon and voice synthesized information identifying the type of weapon that fired the projectile and the effect of the projectile on the user.

36. A tactical training helmet (TTH) for being worn on the head of a user and for use in a laser based tactical engagement simulation training system, said TTH comprising a helmet shell; means embodied in said shell for receiving, processing and decoding information contained in an incoming laser beam, said means for receiving, processing and decoding including laser detectors also embodied in said shell.

37. A TTH as in claim 36, wherein some of said laser detectors face downward from said shell and detect secondary or scattered reflections of the laser beam off of the torso of the user.

38. A TTH as in claim 36, wherein said shell further embodies a GPS receiver for determining the position of the TTH, the information contained in an incoming laser beam includes an identification of the GPS position of the source of the laser beam, and said means for receiving, processing and decoding determines the distance between the GPS coordinates of the TTH and those of the source of the laser beam.

39. A TTH as in claim 38, wherein the incoming laser beam represents a projectile fired by a weapon and contains information about the weapon, and said means for receiving, processing and decoding includes means, based upon the information about the weapon and the distance between the GPS coordinates of the TTH and those of the source of the laser beam, for determining the effect of the projectile on the user.

40. A TTH as in claim 39, wherein said means for receiving, processing and decoding includes sound and voice synthesis means and speaker means embodied in said shell for generating, based upon the information contained in the incoming laser beam, real time sound effects of the projectile fired by the weapon and voice synthesized information identifying the type of weapon that fired the projectile and the effect of the projectile on the user.