Wireless short range communication system

A wireless communications system defining an wireless personal area network enables reliable communications between members of workers in a group wearing compatible systems. Each member of a group is fitted with a communications system having a microphone, a transceiver and a speaker.

TECHNICAL FIELD OF THE INVENTION

This invention relates to a wireless short range communication system that enables reliable communications between and among members of a group wearing compatible systems.

BACKGROUND OF THE INVENTION

Effective and reliable communications between and among team members working in a hostile environment are critical components of safe and effective operations. Whether the team members are firefighters, police, military or other workers whose jobs requires performance in dangerous situations, all such workers benefit when they are able to rely on reliable communications systems. The performance and efficiency of the team also is improved when team members are in full communication.

Individuals working in hostile or dangerous environments, particularly in situations where there is an immediate danger to life or health, generally wear some kind of protective gear. In the case of firefighters, the protective gear often includes full or partial face masks that assist with breathing in smoke or gas-filled environments. While there are many known types of face masks, a typical mask includes a cup-shaped main body that is made of a pliable, air impermeable material, such as rubber. The main body is coupled to a source of fresh air, oxygen-rich breathing mixture, or mechanical filtration mechanism to scrub the harmful environmental air of toxins such as poisonous gas. The mask is placed over the fireman's face and mouth before entering a dangerous environment.

While the mask provides a necessary measure of safety for the fireman, since it covers the individual's face and mouth, it typically causes diminished or disturbed communication between individual wearers of such masks. As individuals who wear such safety equipment know, face masks often diminish communication to the point where communication between the users is not possible. This is especially true in difficult environments, such as burning structures, where such masks must be worn. The mask seal, while acting to block out infiltration of harmful gas, also invariably suppresses voice communication. Even in a quiet environment, an individual speaking while wearing a full face mask cannot be heard clearly by someone else standing near by. Moreover, the environment where these masks are used is typically an environment with the sound of mechanical apparatus, people shouting, weapons being fired, fire hose streams hitting walls and other loud sounds.

Ironically, while a face mask is a mandatory part of safety equipment, it at the same time may diminish worker safety by inhibiting communication among workers.

Various communications systems have been devised to overcome the difficulties just noted. One type of system incorporates a microphone on the interior of the face mask. However, an electrical connector such as a wire penetrates the body of the mask through a small opening. Even if these openings can be sealed adequately when the mask is new, they often leak as the mask ages or wears with use.

Another well known prior art communication device includes a microphone that attaches to a speaker mounted on the body or attaches to long range radios such as radios operating on a VHF frequency. While both have their uses, the primary need of persons wearing full face masks is communication with other team members also wearing full face masks in the immediate vicinity.

There is a substantial need, therefore, for improved systems and apparatus that allow for reliable communications between such team members.

The present invention is a short range, wireless communications system that provides for reliable and effective communications between team-members in a working group, avoiding use of long range broadcast frequencies and thus alleviating radio traffic on those frequencies that are needed by other workers.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

The invention is described and illustrated herein as it may be embodied in a face mask, face shield, and helmet of the type that typically is worn by firefighters and other emergency workers engaged in similar activities in dangerous environments. It will be readily appreciated that the invention is not limited to use by firefighters and the equipment they use, but is useful and applicable in any situation where short range communications between team members facilitates safety and effective work conditions. By way of example and not limitation, the communications apparatus and methods described herein may be used by SWAT team members, hazmat workers, and maintenance workers whose jobs require entry into dangerous environments such as enclosed tanks and the like.

Short range broadcast communications among members of a team—that is, having communication only with those members in the immediate vicinity, facilitated by a communications system according to the present invention, offer a number of advantages over other forms of inter-team broadcast communications.

For example, short range communication facilitates working conversation without interfering with radio traffic on long range communication channels. Small working gmups of 7 or less can share a common short range communication channel in the vicinity while another small working group can share a different communication channel. In many emergency situations there are personnel whose jobs require continued use of long range radio frequencies such as VHF channels. On the other hand, other worker's jobs not only do not require access to long range channels, but continuous “chatter” on long range frequencies interrupts and interferes with these worker's jobs. As an illustration of this principale, a small group of firefighters who enter a burning building must be able to communicate with one another. However, fire command teams and others outside of the building must be able to communicate on long range frequencies. Use of long range frequencies by the individuals in the building impairs outside communications by the command teams, and likewise, communication by the command team interferes with effective inter-team communication between those in the building.

Short range communication also aids in keeping track of, and locating lost team members. Rapid Intervention Team (RIT) standards for firefighters require that a minimum of two firefighters stand by outside a building in full protective equipment, while other crew members are working in a hazardous atmosphere. If a firefighter becomes lost, trapped or disoriented while fighting a structure fire, the RIT team can determine an approximate vicinity of the fallen firefighter by walking outside the structure and determining where the signal is gained or lost. If the structure is large, the RIT team can identify their proximity to the lost team member within about ten meters, which is the maximum ideal distance of the short range communication device. Other advantages of short range inter-team communications are detailed herein.

Turning now to the drawings, and with specific reference toFIG. 1, a communications system10is illustrated in one embodiment worn by a firefighter12. As detailed herein, there are many different combinations of emergency equipment with which the communications system10may be used. Nonetheless, for purposes of illustration, the firefighter12is shown wearing a face mask14, a face shield16, a helmet18and a heat shield20that is incorporated into the helmet. In many instances, the face shield16is designed to provide an air-tight, gas-impermeable seal around the firefighter's face.

The face mask14illustrated herein is a conventional SCBA device that includes a pliable main body22that covers the firefighter's mouth and nose. The main body22is attached to a supply of air24, typically a tank worn on the firefighter's back, with an appropriate high pressure regulator26and face mask14includes a low pressure regulator27. Typically, the high pressure regulator26and low pressure regulator27are designed to maintain a positive air pressure within the mask so that the firefighter12has a continuous supply of fresh air. It will be appreciated that the communications device10described herein may be used with any face mask, including canister or filter type masks that are not attached to an independent air source.

The communication system10includes a microphone30that as described below is a wireless, voice activated and short range microphone, and a transceiver60, which in the embodiment shown inFIG. 1is embodied as an earphone-type device worn attached to the ear of firefighter12. As described below, the communications system10also may include optional sensors worn by firefighter12, such as sensor100. Each component will be described separately.

Microphone30is, in the illustrated embodiment, a voice activated, wireless microphone that utilizes active noise cancellation protocols. It is at times referred to herein as transmitter30. Alternately, microphone30may be of the type that is remotely activated—although wirelessly—by the firefighter depressing a “talk” button.

As shown inFIG. 1, microphone30is housed entirely within the interior of main body22of face mask14. Because the microphone is a wireless device, there are no wires or other communications devices that penetrate the body of face mask14that could compromise the integrity of the gas-tight seal between the mask and the user's face.

Microphone30is small enough so that it is held in proximity to the mouth of firefighter12, but does not interfere with the firefighter's normal activity or speaking. The microphone may be mounted in any appropriate position within the interior of the face mask. With reference toFIG. 2, microphone30is shown in an exploded view to detail its components, which include the microphone32, a power supply34such as a battery, and an activation switch36. Microphone30and battery34are received and mounted in a mounting housing38, which is attached to the interior surface of main body22of the face mask14. Housing38is sized to receive microphone30and battery34, and also a biasing member such as a spring40that is interposed between the battery34and a base plate42. Housing38preferably is a pliable material that allows easy insertion and removal of microphone30and its component parts from the housing, for instance, when it is necessary to replace battery34. The housing38may be attached to the interior surface of main body22by any convenient method, such as adhesives, hook and loop fabric fasteners, etc., so that the communications system10may be added to or retrofitted in existing face masks. Likewise, the communications system may be added to new equipment.

Activation switch36comprises a removable plug44that has a lanyard46attached to it. The plug44is sized to be inserted into an opening48formed in microphone30. When plug44is inserted into opening48, the electrical circuit that powers microphone30is open. That is, the microphone is off or inactivated. When plug44is removed from opening48the electrical circuit is closed, thereby activating the microphone. The plug44may be used to activate a variety of different switch types, including for example a mechanical switch, an electronic switch or an electromagnetic switch. An indicator light50such a light emitting diode illuminates when the circuit is closed to indicate that the microphone30is activated, or switched on. When plug44is inserted into opening48, the plug acts as a barrier to entry of foreign substances, dirt and the like, so the plug therefore helps to keep the opening clean.

Lanyard46is sized long enough that it extends beyond the outer limits of the face mask. In other words, whenever the face mask14is worn by a firefighter, the lanyard46, unless removed, interferes with the seal between the face mask and the firefighter's face, or must be manually tucked into the face mask. Accordingly, the lanyard acts not only as a convenient and simple way to activate the microphone30by pulling on and thus removing plug44, but also serves to remind the firefighter to turn the microphone on whenever the face mask is being used. This prevents the situation where the firefighter inadvertently forgets to turn on the microphone.

As noted, microphone30is in a preferred embodiment a voice activated, wireless transmitter that converts voice communication using digital signal processing into a digital signal that is transmitted to one or more other wireless short range frequency transceivers that are worn by individuals in a working group. Preferably, microphone30is suitable for operation in the ISM (Industry Scientific and Medical) band, which is the unregulated frequency band beginning at 2.402 GHz and ending at 2.483 GHz in the U.S. and Europe. The ISM band defines 79 RF channels, each of 1 MHz width. The Bluetooth protocol is an example of such an ISM band operation for a “Wireless Personal Area Network” (WPAN), as is the IEEE 8.02.11 standard. For purposes herein, a WPAN may be considered to be an area defined as the working area for a team of workers where proximal devices may share information and resources such as communications between devices in the WPAN. For the Bluetooth protocol, the WPAN is the short range area from zero to about ten meters.

Referring once again toFIG. 1, firefighter12wears a transceiver60positioned near his ear. Transceiver60may take different forms, and as described below, may be positioned at other locations. Nonetheless, in the embodiment illustrated inFIG. 1, transceiver60is shown as an earphone type device that is worn on the ear. Transceiver60incorporates a speaker61so that communications may be heard by firefighter12, and communications electronics that cooperate with microphone30to clarify voice communications and remove or cancel ambient noise. As with the microphone30, transceiver60is operable in the ISM band, preferably using the Bluetooth protocol or other appropriate protocol for WPAN communications.

FIGS. 5 and 6show other illustrated embodiments in which the transceiver60is located in other positions, with the same results as the embodiment shown inFIG. 1. InFIG. 5the transceiver60is physically separated from the speaker. Thus, transceiver60is mounted to the outer surface of firefighter12's face shield16. In this case, a speaker module70housing a speaker may be positioned by the user's ear in an earphone-type enclosure. Likewise, the speaker may be mounted to a housing that attaches to the user's helmet, heat shield, or other protective headgear. InFIG. 6the transceiver60is mounted to a boom66that is rotatably mounted to face mask14so that the boom66may be positioned such that the transceiver and its enclosed speaker is positioned near the user's ear. In either case, the transceiver and the speaker modules include adequate power sources and electronics. The foregoing demonstrates two of the many different and equivalent structures for mounting the transceiver and speaker, either alone or together.

Regardless of how the transceiver60is mounted, as shown inFIG. 3, the transceiver preferably incorporates a speaker61that may be positioned in operational proximity to the user's ear, a receiver72, a short range transmitter or microphone74, a power supply76and an on I off switch78. In the illustrated embodiment, on/off switch76is a switch of the same type described above with reference to the plug44that acts as the switch for microphone30. Thus, a lanyard79is attached to a plug81that is inserted into an opening in the transceiver. The plug81operates in the same way that plug44operates: when the plug is removed by pulling lanyard79, the electrical circuit that powers transceiver60is closed so that the transceiver is powered on. Preferably, plug44and plug81are of the same size and configuration so that they are thus interchangeable. The receiver72is configured for receiving digital signals from other transmitters in the WPAN. As with the microphone30, the transmitter74in transceiver60is a wireless transmitter that converts voice communication using digital signal processing into a digital signal that is transmitted to one or more other wireless short range frequency transceivers that are worn by individuals in a working group. It will be appreciated that In transceiver60, the transmitter74and receiver72may be a common, multifunctional apparatus. The power supply76is preferably a replaceable battery, and the on/off switch78may, in addition to the plug and lanyard switch described above, be a standard switch such as a push-button switch, preferably with a status indicator light.

In one embodiment, communications system10incorporates noise cancellation protocols in the internal electronics in order to clarify spoken communications and minimize ambient environmental noise. As noted above, personnel using communications systems10often work in difficult and noisy conditions. Moreover, respiration equipment itself creates noise as compressed air rushes through the regulator into the face mask when a breath is drawn. Regulator noise is usually louder than the spoken word, and as such, simple voice activation switches may be ineffective. Signal processing can alleviate environmental noise such as the noise from a respirator through volume level cancellation. Relative thresholding of the sound received by the microphone within the mask can cancel the respirator noise. Removal of the respirator noise can also occur through signal processing the frequency of the sound of the respirator.

More specifically, prior to transmitting the digital signals representing voice communications, the signal is processed to clarify the voice and remove ambient noise. The ambient noise cancellation preferably incorporates a secondary microphone such as microphone74located outside the face mask14, which is the originating point for the noise or sound that is to be cancelled. In one preferred embodiment, the secondary microphone74is located on transceiver60, which thus acts as a receiver of digitized voices from other transmitters in the wireless network. Noise cancellation may be accomplished according to any one of several protocols. In a first embodiment, the noise cancellation is accomplished with electronics carried in the housing for transceiver60. In this system, signals from microphone30are transmitted to transceiver60and are processed to cancel ambient noise in the microphone carried in transceiver60.

Alternately, transceiver60may be configured as a transmitter that will transmit the ambient noise signal to the microphone30located within the mask. The signal processing masks the environmental noise with the voice signal to cancel the external ambient sounds. The signal processing will determine the origin of the sound, whether it is internal or external to the mask by a volume comparison. Those sounds where the volume is louder from the microphone at the transceiver60than the microphone30within the face mask14are by definition ambient noise due to the shielding effect that the facemask has to external sounds. Those sounds where the volume is louder from the microphone30in the face mask14than the sounds transmitted from the transceiver60are sounds that are to be broadcasted.

Signal processing may also be used to perform noise cancellation. For example, the transceiver60may include circuitry that enables cancellation of noise in a predetermined frequency band that corresponds to an expected noise—such as the frequencies that are typical of the sound of air rushing into the face mask14.

Transceiver60preferably includes switching circuitry responsive to microphone30so that when the receiver72in transceiver60is not detecting signals corresponding to a user's voice transmitted from microphone30, the transceiver60is in receiving mode. In this receiving mode, transceiver60is capable of receiving voice communications from microphones worn by other firefighters in the working group. When receiver72in transceiver60detects a signal from microphone30worn by firefighter12, the signal thus corresponding to the user's voice, the transceiver switching circuitry switches the transceiver to a second, transmitting mode. In this transmitting mode, the secondary microphone74broadcasts the signals to the receivers72in other transceivers60worn by others in the working group. The voice communications from firefighter12are thus broadcast to other members of the group.

Turning now toFIG. 4, a group of firefighters with reference number12a,12b,12c,12dand12eare shown schematically in a diagram that represents a working group of firefighters, each wearing a communications system10according to the present invention In a WPAN, labeled as54. Each firefighter12In the group is wearing a communications system10according to the present invention, including a microphone30and a transceiver60. inFIG. 4structures that are common to the figures already described are numbered in a like fashion, such as transceivers60a,60b, and so on. Furthermore, for purposes of explaining the communications system10inFIG. 4its will be assumed that the WPAN is operating in a Bluetooth communications protocol.

As noted above, and briefly described, Bluetooth operates in the ISM frequency band from 2.402 GHz to 2.483 GHz, providing 79 RF channels of 1 MHz width. Two or more units communicating on the same channel in a Bluetooth WPAN form a piconet, where one unit operates as a master and the others in the piconet operate as slaves. A piconet is an ad hoc network created when two or more Bluetooth-enabled devices recognize one another and communicate. There is a maximum of seven active units in a piconet at any one time. Slaves in the piconet synchronize their timing and frequency hopping to the master upon establishment of a connection.

In the illustration ofFIG. 4, each transceiver60athrough60eparticipates in the WPAN as a master node in each individual firefighter's individual piconet—that is, the piconet established between the firefighter's transceiver60and the same firefighter's microphone30. With specific reference to firefighter12ainFIG. 4, that firefighter's master node may have up to 6 slave devices, such as firefighter's microphone30aand the transceivers60b,60c,60dand60eworn by firefighters12b,12c,12dand12e, respectively. Inter-member communications are illustrated by the arrows extending between and among members of the work group.

Inter-piconet communication among members of a working team is accomplished by creating a scatternet, which may be defined as a group of independent, non-synchronized piconets that share at least one common Bluetooth-enabled device. This is accomplished by a transceiver60creating a bridge between two or more piconets. Bridges are master-slave such that the transceiver60in one piconet may be the slave of another piconet. Creating a primary master that maintains the piconet with the receiver, additional sensors, and one or more other transceivers as master-slave bridges establish the Bluetooth topology. These transceivers, acting as a slave to the primary master will also act as a sub-master to other transceivers as master-slave bridges. The Bluetooth specification allows for changing topology as members of a work group enter and leave the WPAN.

With reference toFIG. 7, a scattemet Is illustrated in schematic form. Each firefighter12(i.e.,12a,12b,12c,12d,12e) wears a communications system10comprising at least a microphone30and transceiver60. As such, as detailed above, each firefighter12in the work group thus defines an Individual piconet between the transceiver60and microphone30. Firefighter12ais the primary master transceiver60in the scatternet, and there are five nodes in the piconet: one defined by the receiver in transceiver60a, one defined by microphone30a, and three bridge nodes to the three transceivers60b,60cand60d(worn by firefighters12b,12cand12d, respectively). Likewise, transceivers60cand60dhave three nodes in their respective piconets. Transceiver60bworn by firefighter12bfurther is designated as a sub-master transceiver. It has four nodes in its piconet: one defined by the receiver in transceiver60b, one defined by the microphone30b, one defined by a VHF frequency adaptor90b(detailed below) and one bridge node to transceiver60e. Firefighter12dis also shown as wearing a VHF frequency adaptor90d, and firefighter12eis shown wearing an environmental sensor100e. VHF frequency adaptor90may be used in situations where it is necessary to relay communications from the short range system10described herein to the longer range VHF frequencies. VHF frequency adaptor90defines yet another communication device in communications system10that is within the WPAN. Adaptor90is configured to connect to VHF radio frequencies so that communications broadcast on VHF frequenciesfor example, by workers outside of the WPAN who are using VHF radios, are broadcast to workers within the WPAN. Nonetheless, the transmitters30worn by firefighters12located within the work group in the WPAN are configured to “talk over” transmissions received on the VHF adaptor90. In this way, radio traffic on the VHF channels does not interfere with communications within the WPAN. Stated another way, adaptor90is not able to transmit VHF communications while there are communications ongoing within the WPAN.

Likewise, any communications by firefighters12within the WPAN remain only within the WPAN until a group member wearing a VHF adaptor90, such as firefighter12b, activates or “keys” the adaptor90. At that time, any discussions amongst the group members in the WPAN are transmitted over the VHF radio to workers outside of the WPAN.

When one of the firefighters12athrough12eenters the WPAN defined by the combined communication systems10, the transceiver60worn by the entering firefighter joins the existing group as a slave to either the primary master60aor to a sub-master (e.g.,60b). The transceiver entering the group then passes on information about the individual's piconet to all other members in the network, and the other members of the group pass information about the group to the new member.

If the individual that is established as the primary master of the scatternet (in the example ofFIG. 7, firefighter12a) departs from the group—that is, departs from the bounds of the WPAN, the first slave node with the smallest number of nodes within its piconet takes over as the primary master and the topology of the scatternet is adjusted accordingly.

As noted earlier, the communications systems10may be preprogrammed to broadcast information to members of a working group in a WPAN information about an individual. The information that is broadcast may take many different forms. For example, the information may be voice data defined by a prerecorded spoken voice, or synthesized voice. As an example of this type of information being broadcast, when other team members join a working group, all members may be alerted that the new member joining is within the WPAN. This is done by the transceiver60broadcasting an audible, spoken message comprising the member's pre-recorded voice announcing his or her name to all other team members, such as “Johnson joined.” Likewise, when a team member has departed the WPAN boundaries, the team is alerted that a member has left the proximity by a pre-recorded broadcast transmitted from transceiver60such as “Johnson left.” By using the team member's own pre-recorded voice as a broadcast message, other members of the group have an easier time in the identification of that team member since other team members will be more apt recognize the voice and associate it with the team member's name. Proper identification of team members is often important because failure to identify the team members may lead to dangerous assumptions about the experience or skills of the team members and the location of other members. The broadcast of the team member's own pre-recorded voice when joining a team aids in the identification of that team member, for when they speak again, other team members will recognize the voice and associate it with the team member's name. Similarly, the predetermined broadcast information may be a message such as “evacuate”, or an audible beep or buzz to signal members of the group that one member's equipment needs maintenance, such as when the air supply is low.

In addition to the foregoing examples of where short range inter-team communications are beneficial, emergency response personnel wearing gas masks or SCBA have a need to know the status of their environment, the equipment in use, and other team members' health. Just as importantly, other team members also need to know the status of the user's environment, equipment status, and user's health. Sensors placed on the breathing apparatus can signal to the working team that one member is low on air or pending equipment malfunction. New standards require that firefighter masks have a heads-up display with lights to display the pressure level remaining in their air tanks. In a fire situation, firefighters often develop “tunnel vision” and ignore the lights displayed on their mask. Having an audible reminder transmitted by a short range communication system of the gas level in their tanks may increase the awareness of their remaining air in their tank, and hence their safety.

Similarly, an environmental sensor can provide valuable information to the emergency response personnel such as if the environment is safe to breathe, in that gases have dissipated to healthful levels so that the breathing apparatus is no longer required. Sensors placed on the emergency response personnel may also monitor the health of the user and be programmed to broadcast specific information to other members of the team, alerting other team members of a dangerous condition, for example if any members' vital signs are elevated or diminished to an unhealthy level.

Sensors can broadcast the information directly to the working team or broadcast data only to the wearable computing device/transceiver that in turn analyzes the sensor's data and broadcasts English or other language messages to the team when sensor data is out of the norm, such as, “Johnson low on air, 20% remaining.”

The information that is generated by communications system10and passed between group members in this manner may be predetermined according to the particular situation and is referred to herein as member data. For example, member data information may include the member's name, his or her rank within the emergency services organization, the topology of the scatternet, and information about the sensors carried by each member's piconet. If one member of the group has a sensor for environmental temperature such as sensor100eworn by firefighter12e, member data information about that sensor is passed to other members of the team. In this way, all members of a team may share data output by environmental sensor100e. This reduces the number of environmental sensors100that are required.

Sensors100placed on the emergency response personnel may also monitor the health of the user alerting other team members if any members' vital signs are elevated or diminished to an unhealthy level. Member data may thus further comprise health status information about individual members.

Sensors100preferably broadcast member data through a pre-recorded English or other spoken language message that is easily understood by the members of the working team. In tense emergency situations, it is better to use spoken language than number codes or a series of tones to communicate sensor information that is outside the normal parameters. Sensors100can broadcast the member data information directly to the working team or broadcast data only to the wearable computing device/transceiver that in turn analyzes the sensor's data and broadcasts spoken language messages to other group members information about the status of the sensor, such as out-of-norm conditions (e.g., “Johnson low on air, 20% remaining”).

It will be appreciated from the foregoing description that various alternative embodiments may be made. As an example, the transmitter/microphone30may be placed outside of face mask14but within face shield16. In this position the microphone is still able to pick up voice signals from the user, although the signals are not as strong given that the face shield naturally muffles the user's voice. However, in this case where microphone30is positioned externally to the face mask14, the microphone may further act as a transceiver. As an example, a sensor such as sensor100may be located on or before the high pressure regulator and configured to transmit data about the pressure, or fullness, of the SCBA cylinder. The transceiver located within the mask may have 4 LED lights that illuminate to indicate the status of the amount of air remaining in the tank: four lit indicates full, three lit indicates ¾ full, two lit indicates ½ full, one lit indicates ¼ full, and one blinking indicates less than some predetermined amount, e.g., 500 psi, which is a commonly accepted danger point to change cylinders. In addition to LED light indicators as just explained, the data sent to the transceiver may be any type of data, and it may be displayed on any number of devices such as LCD displays, heads-up displays, laser writing, etc.

Current federal safety regulations stipulate that a firefighter must have an unobstructed view of how much air is in the SCBA cylinder. SCBAs manufactured under current standards are required to have a heads-up display that will display visual alert signals for breathing air cylinder content and for battery condition. The HUD as exemplified by the LEDs detailed above will display a visual alert signal for breathing air cylinder content when the breathing air in the SCBA cylinder has reduced to 50 percent of rated service content.

As yet another example of an alternative embodiment, a wireless transmitter may be positioned either outside of the face mask14but within face shield16, or external to the face shield16, with a microphone positioned in an operative location within the face mask. The communications system10according to the present invention may utilize a transmitter30located entirely within face mask14as shown in the drawings and as detailed above, or the transmitter may be located in other positions when coupled with a microphone operatively positioned to pick up the users spoken voice. The transmitter must in this manner be associated with the face mask so that the user's voice may be transmitted in the WPAN.

While the present invention has been described in terms of a preferred embodiment, it will be appreciated by one of ordinary skill that the spirit and scope of the invention is not limited to those embodiments, but extend to the various modifications and equivalents as defined in the appended claims.