Abstract:
A personal safety device includes a buoyant component and a tracking device coupled to the buoyant component. The tracking device includes a location determining device and a wireless communication device. The wireless communication device is configured to communicate with a terrestrial communication network such as a cell phone network. The wireless communication device is effective in coastal and inland waters, and the reduced size as compared with satellite telephones makes the device practical use during recreational water activities. Various buoyant components including personal floatation devices, waterproof containers, and gas trapping encapsualtions are disclosed.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates generally to personal tracking devices, and more particularly to a personal tracking device having a buoyant component. Even more particularly, the invention relates to a personal tracking device in combination with a personal flotation device (PFD). 
         [0003]    2. Description of the Background Art 
         [0004]    Tracking devices embedded in personal flotation devices (PFDs) are known in the art. These devices are typically used in emergencies as a means to locate persons who are lost at sea, or have become separated from their vessel. 
         [0005]    A problem with some prior art tracking devices is that they require mechanical activation by the user. However, in an emergency situation, a user may not be able to activate the device due to injury, unfamiliarity with the operation of the device, or some other reason. To address this problem, devices with automatic trigger mechanisms have been developed. 
         [0006]    One such device is described in U.S. Pat. No. 6,439,941 (McClure et al.). The device of McClure et al. is a controller based device that includes a GPS receiver, a satellite radio-telephone, and a trigger mechanism. Upon activation of the trigger mechanism, the GPS receiver determines the current position of the device and transmits a distress signal including the determined position to a rescue organization such as the Coast Guard. 
         [0007]    The device of McClure et al. has several disadvantages. For example, the device of McClure et al. relies on a trigger mechanism. In particular, a hydrostatic pressure detector triggers the activation of the device when the pressure detector senses a minimum specified submersion of the device for a specified duration. Further, the device deactivates when removed from the water, and the controller ceases transmission. This system relies on electronics for triggering activation, and may become deactivated or simply not activate if the hydrostatic pressure detector is faulty or not sufficiently submerged. This could be problematic if the wearer is not in the water. Conversely, if a tracking PFD not being worn were inadvertently lost from a vessel a false alarm could be triggered, and rescuers would waste valuable time searching for the PFD. 
         [0008]    Another disadvantage is that the device of McClure et al. is relatively heavy and bulky and is, therefore, impractical for the average recreational user. The size and weight are due at least in part to the batteries and satellite radio-telephone, which are required to be functional on the open sea. As many boaters, jet-skiers, and water sports participants will understand, the overall size and weight of their PFD is extremely important to their comfort and ability to perform many activities such as waterskiing, wakeboarding, tubing, and so on. The device of McClure et al. is simply too large and heavy to be comfortably used during most recreational water activities. 
         [0009]    The PFD of McClure et al. is also impractical for use in water sports activities, because the GPS receiver and satellite radio-telephone are activated when the hydrostatic pressure detector is submerged in water. Therefore, the PFD could not be used by water sports participants, because many water sports activities such as wakeboarding or waterskiing require the participant to be submerged in water at certain times. In those cases, the PFD would transmit an unintended distress signal. 
         [0010]    Yet another problem associated with the device of McClure et al., as well as other prior art devices, is that users may elect not to wear bulky or uncomfortable PFDs. If the user is not wearing the tracking PFD, the device may be ineffective. For example, if a user became separated from the tracking PFD during an accident, then the user could not be tracked. As another example, if the user fell overboard, but the PFD remained on the vessel, then the device would not be activated. 
         [0011]    Another problem with prior art tracking PFDs is that the tracking mechanisms may be susceptible to damage from shocks and impacts routinely encountered in high speed water sports. Known devices were simply never intended to be subjected to such shocks and impacts. Rather, the devices were primarily intended to facilitate rescue at sea. 
         [0012]    In view of the problems with the prior art, what is needed is a PFD with a tracking device that does not require a trigger for activation of the tracking device. What is also needed is a PFD with a tracking device that does not generate false alarms when the wearer is intentionally in the water. What is also needed is a PFD with a tracking device that is operational even when the wearer is not in the water. What is also needed is a PFD with a tracking device that is smaller in size and lighter in weight. What is also needed is a PFD with a tracking device that is practical for use when participating in recreational water sports. What is also needed is a PFD with a tracking device that facilitates tracking of the user when the PFD is not being worn by the user. 
       SUMMARY 
       [0013]    One aspect of the present invention overcomes some or all of the above-described problems associated with the prior art by combining a tracking device with a buoyant component (e.g., a wearable PFD, waterproof canister, buoyant encapsulation). The size and weight of the device are minimized by using a terrestrial based wireless communication device (e.g., a cell phone modem) as opposed to a satellite radio-phone. The inventors have realized that eventhough the wireless communication device would be out of range on the open seas, the device can be effectively utilized in coastal and inland waters, where a significant amount of recreational water activities occur. 
         [0014]    The present invention includes a buoyant component and a tracking device coupled to the buoyant component. The tracking device includes a location determining device and a wireless communication device electronically coupled to the location determining device. The wireless communication device (e.g., a cell phone modem) is configured to communicate with a terrestrial communication network (e.g., cellular network) to facilitate transmission of location data to a remote station. Optionally, the terrestrial communication network is exclusively land based. 
         [0015]    The tracking device further includes a communication antenna and a location signal antenna. The communication antenna is electrically coupled to the wireless communication device. The location signal antenna is electrically coupled to the location determining device. In the embodiments shown, the communication antenna and location signal antenna are omni-directional antennas, but other types of antennas could be used instead. In one embodiment, both the location signal antenna and the communication antenna are disposed within the encapsulated tracking device. 
         [0016]    In normal operation, the wireless communication device periodically transmits position information from the position determining device regardless of the existence of an emergency situation. The position determining device determines the position of the tracking device using signals transmitted by a positioning system (e.g., a satellite GPS system). Alternatively, the location determining system obtains information indicative of the position of the tracking device exclusively via the wireless communication device. 
         [0017]    In a particular embodiment, the buoyant component is a PFD. The tracking device is detachably coupled to the PFD and is functional even when detached form the PFD. Means for detachable coupling the tracking device to the PFD include, but are not limited to, a clip, a lanyard, VELCRO®, a pocket, and so on. The PFD optionally includes built-in auxiliary or redundant components (e.g., batteries, antenna, charging connector, and so on) for use with the detachable tracking device. In one particular embodiment, a flexible circuit substrate is disposed beneath the outer fabric layer of a PFD and extends from a pocket of the PFD to the desired antenna locations, for example the upper shoulder section of the PFD. The tracking device includes a connector for connecting to the flexible circuit substrate when the tracking device is placed within the pocket of the PFD. Optionally, a cover or rubber cap sewn on to the outer material layer of the PFD provides additional protection for the antennas and any charging connector. 
         [0018]    In another embodiment, the buoyant component is formed integrally with the tracking device. The tracking device is encapsulated in a waterproof material (e.g., a polyamide resin). The encapsulating waterproof material defines a slot to facilitate the insertion of a memory device (e.g., a Subscriber Identification Module or SIM card) to uniquely identify the wireless communication device. The slot is sealed (e.g., by adhesive, removable plug, etc.) after the memory device is inserted. In addition, the waterproof material defines at least one internal chamber containing a gas (e.g., encapsulated air pockets). Alternatively, the waterproof material is itself buoyant. In either case, the encapsulation serves as a buoyant component, such that the tracking device is also buoyant in water even when detached from the PFD. 
         [0019]    The encapsulating material also defines a slot for receiving a battery. The wireless communication device is mounted on a circuit board that has a battery connector mounted thereon. The encapsulating material encapsulates a first portion of the battery connector that is connected to the circuit board and leaves a second portion on the connector exposed to facilitate connection to the battery. The battery receiving slot guides the battery into engagement with the battery connector. Optionally, the battery slot can be sealed once the battery is inserted therein. In alternative embodiments, the battery is non-removable, and included within the encapsulation material of the encapsulated tracking device. 
         [0020]    In another embodiment, the buoyant component is a watertight container designed to receive the tracking device. In the particular embodiment shown, the container includes a primary vessel and a hinged lid. In addition, the container includes auxiliary components including, but not limited to, a power source, an antenna, and a charging connector. The lid traps air within the vessel so that the container is buoyant when the tracking device and the auxiliary components are enclosed therein. The disposition of the tracking device, the auxiliary components, and the trapped air within the container is such that the antenna(s) of the tracking device are disposed near the top of the container when the container is floating. 
         [0021]    A safety system utilizing a tracking device of the present invention is also disclosed. The safety system includes a terrestrial based wireless communication network, a buoyant tracking device, and a tracking system. The buoyant tracking device connects wirelessly to the communication network. The tracking system is configured to receive location data from the tracking device via the wireless communication network. 
         [0022]    A method for manufacturing a personal safety device is also disclosed. The method includes providing a buoyant component, providing a tracking device having a wireless communications device configured to communicate via a terrestrial communications network, and coupling the tracking device to the buoyant component (e.g., removably placed within a pocket, permanently embedded within the buoyant component, and so on). 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The present invention is described with reference to the following drawings, wherein like reference numbers denote substantially similar elements: 
           [0024]      FIG. 1  is a block diagram of a tracking system; 
           [0025]      FIG. 2  is a front view of a PFD with a tracking device coupled thereto for use with the tracking system  100  of  FIG. 1 ; 
           [0026]      FIG. 3A  is a front view of the tracking device of  FIG. 2 ; 
           [0027]      FIG. 3B  is a side view of the tracking device of  FIG. 3A ; 
           [0028]      FIG. 4A  is a side view of a container for use with the tracking device of  FIG. 2 , when the tracking device is removed from the PFD; 
           [0029]      FIG. 4B  is a side cross-sectional view of the container of  FIG. 4A , with the tracking device of  FIG. 2  disposed therein; 
           [0030]      FIG. 5  is a partially cut-away front view of an alternate PFD with an embedded tracking device disposed therein; 
           [0031]      FIG. 6  is a front view of another alternative PFD with auxiliary components for use with a removable tracking device; 
           [0032]      FIG. 7  is a partially cut-away front view of the PFD of  FIG. 6  showing the tracking device and auxiliary components; 
           [0033]      FIG. 8A  is a front view of the tracking device of  FIG. 6 ; 
           [0034]      FIG. 8B  is a side view of the tracking device of  FIG. 6 ; 
           [0035]      FIG. 9A  is a side view of a container for use with the tracking device, when the tracking device is removed from the PFD of  FIG. 6 ; 
           [0036]      FIG. 9B  is a cross-sectional view of the container of  FIG. 9A , with the tracking device of  FIGS. 8A-8B  disposed therein; 
           [0037]      FIG. 10  is a flowchart summarizing a method for manufacturing a buoyant tracking device. 
       
    
    
     DETAILED DESCRIPTION 
       [0038]    The present invention overcomes problems associated with the prior art, by providing a tracking device coupled to a buoyant component. The tracking device includes a wireless communication device configured to communicate via a terrestrial based network (e.g., a cell phone network). The tracking device can be conveniently attached to wearable PFDs and other buoyant components, because of the device&#39;s relatively small size as compared to a satellite telephone. In the following description, numerous specific details are set forth (e.g., particular electronic components, particular buoyant components, etc.) in order to provide a thorough understanding of the invention. Those skilled in the art will recognize, however, that the invention may be practiced apart from these specific details. In other instances, details of well known PFD manufacturing and electronics assembly practices and components have been omitted, so as not to unnecessarily obscure the present invention. 
         [0039]      FIG. 1  is a block diagram of a tracking system  100  including a buoyant tracking device  102 . Tracking system  100  further includes a subscriber server  104 , a terrestrial wireless communication link  106 , an internetwork  108 , one or more subscribers  110 ( 1 - n ), and a positioning system  112 . 
         [0040]    Tracking device  102  communicates wirelessly with subscriber server  104  via terrestrial wireless communication link  106 . In the particular embodiment described, terrestrial wireless communications link  106  is a mobile telephone network. However, the invention is not limited to use with any particular type of mobile telephone network. Indeed, terrestrial wireless communication link  106  represents any means of wireless communication, now known or yet to be discovered, that facilitates communication between tracking device  102  and subscriber server  104  including, but not limited to cellular networks (e.g., CDMA and GSM), WIFI networks, and radio communication, so long as the communication network is terrestrially based. 
         [0041]    Subscriber server  104  receives data from tracking device  102  indicative of the geographic position of tracking device  102 , and provides the information to subscribers  110 ( 1 - n ) via internetwork  108 . In this particular embodiment of the invention, internetwork  108  is the Internet. However, any suitable means of communication between subscriber server  104  and subscriber servers  110 ( 1 - n ) can be used for internetwork  108 . 
         [0042]    Subscribers  110 ( 1 - n ) represent individuals with an interest in the location of the person wearing tracking device  102 . For example tracking system  100  can be used by emergency service personnel to locate boaters in distress, by remote data logging devices to provide periodic location tracking logs for users, and so on. Subscribers  110 ( 1 - n ) communicate with subscriber server  104  via internetwork  108  using some sort of client device including, but not limited to, a personal computer, a telephone, and so on. 
         [0043]    Responsive to a command from subscriber server  104 , tracking device  102  determines its location using location signals received from positioning system  112  and transmits data indicative of the determined system back to subscriber server  104 . Positioning system  112  represents any type of satellite or terrestrial based positioning system that transmits signals that can be used to determine location. For example, a global positioning system (GPS) currently in use employs a plurality of satellites that continuously transmit signals. GPS receivers can calculate location by determining the difference in the time of receipt of signals from different satellites. GPS technology is well known, and so will not be described in detail herein. 
         [0044]    As an alternative to a GPS type system, positioning system  112  can be incorporated into terrestrial wireless communication link  106 . For example, wireless telephone networks now have the capability of determining the location of mobile telephone handsets based on signals from a plurality of signal towers in the network. Terrestrial wireless communication link  106  can then provide the determined location directly to tracking device  102 , which in turn can communicate the location to subscriber server  104 . As a result, positioning system  112  can be thought of as either optional or as being incorporated into terrestrial wireless communication link  106 . 
         [0045]      FIG. 2  is a front view of tracking device  102  coupled to a buoyant component  200 . In this particular embodiment, buoyant device  200  is a wearable personal flotation device (PFD). Tracking device  102  is removably disposed in a pocket  202  on the outer surface  204  of PFD  200 . Pocket  202  is a mesh pocket that is fastened to the outer surface  204  of buoyant device  200  in the upper chest or shoulder region and includes an opening  210  generally located at the top of pocket  202 . Pocket  202  further includes an elastic cord  206  and clasp  208  that in combination, allow for tightening and loosening of pocket opening  210 . The tightening and loosening of pocket opening  210  allows tracking device  102  to be inserted or removed from PFD  200 . 
         [0046]    Pocket  202  does not penetrate the inner chamber of PFD  200 . Therefore, pocket  202  and tracking device  102  should not adversely impact the buoyancy or life preserving functionality of PFD  200 . This is an advantage, because tracking device  102  and pocket  202  can be incorporated into existing PFD designs without adversely affecting the approval (e.g., Coast Guard approval) of those designs. 
         [0047]    In this particular embodiment, PFD  200  includes three full wrapping straps  212 , each having a two part fastener  214 , to allow a user to easily put on or remove the PFD. Straps  212  and fasteners  214  are common to many wearable PFDs on the market today. The quantity and placement of straps  212 , fasteners  214 , and pocket  202  may vary according to the particular design of the PFD. 
         [0048]      FIG. 3A  is a front view of tracking device  102 , which is shown to include a controller  302 , a GPS receiver  304 , a wireless modem  306 , a SIM card socket  308 , a power supply  310 , all mounted on a circuit board  312 . Controller  302  includes a processing unit and code, which when executed provides overall coordination and control of the various functions of tracking device  102  described herein. GPS receiver  304  is electrically coupled to GPS antenna  320 . GPS receiver  304  processes location signals received via GPS antenna  320  and provides the current location of tracking device  102  to controller  302 . Wireless modem  306  is electrically coupled to global system for mobile communications (GSM) antenna  322 . Wireless modem  306  is able to establish a connection with subscriber server  104  via terrestrial wireless communication link  106 , as described above with reference to  FIG. 1 . SIM card socket  308  is designed to receive a subscriber identification module  314 , which includes data that uniquely identifies the card (e.g., a phone number) and facilitates access to terrestrial wireless communication link  106  (e.g., a wireless telephone network). 
         [0049]    Power supply  310  is coupled to charging contacts  326  and is coupled to a battery  336  via a battery connector  316 , which is also mounted on circuit board  312 . Battery  336  is shown in phantom lines in  FIG. 3A , so as not to obscure the view of the other components. When charging contacts  326  are connected to an external charger/power source, power supply  310  draws power from the external source and charges battery  336 . During normal operation of tracking device  102 , power supply  310  draws power from battery  336  and provides power to each component of tracking device  102 , at whatever voltages are required by the particular components, via voltage supply lines  318 . Although voltage supply lines  318  are shown as a single line, it should be understood that voltage supply lines  318  will include as many lines as necessary to satisfy the voltage/power requirements of the particular components. 
         [0050]    An encapsulation material  328  encapsulates circuit board  312  and all of the components mounted thereon. With a few exceptions, encapsulation material  328  completely encapsulates tracking device  102 . The first exception is a slot  340  that facilitates removal and reinsertion of SIM card  314  during initial activation. Once tracking device  102  is activated, slot  340  is sealed with an epoxy, a plug, or any other water tight means (not shown). The second exception to complete encapsulation of tracking device  102  is that a portion of battery connector  316  is left unencapsulated to facilitate the insertion and removal of battery  336 . Optionally, battery  336  is completely and permanently encapsulated in tracking device  102 . The third exception is that portions of charging contacts  326  are left unencapsulated to facilitate electrical contact with devices such as charging units or auxiliary batteries. 
         [0051]    Tracking device  102  also includes indicator light emitting diodes (LEDs)  324 , which are electrically coupled to circuit board  312  and functional to provide feedback to the user. Such feedback may include battery level, signal strength, communication status, and so on. In this particular embodiment, indicator LEDs  324  are switched by controller  302  and are operative to emit multi-colored light, blinking light, and so on, in order to display the necessary feedback to the user with the minimum number of LED lights. 
         [0052]    Also included in tracking device  102  is an inductive charging unit  334 . Inductive charging unit  334  is an optional item, and may serve as an auxiliary or redundant charging source for tracking device  102 . Inductive charging unit  334  is electrically coupled to power supply  310  and battery  336  in a similar manner to charging contacts  326  as previously described herein. Inductive charging unit  334  provides a means for charging tracking device  102  wirelessly and provides an advantage in embodiments where tracking device  102  is completely embedded in a PFD or other buoyant component. In such embodiments (e.g.,  FIG. 5 ), tracking device  102  can be charged even though it is inaccessible. 
         [0053]    Encapsulation material  328  also provides buoyancy to tracking device  102 . In particular, encapsulation material  328  defines internal gas chambers  330 . Internal gas chambers  330  are simply chambers or voids formed in the encapsulation material  328  that contain a gas (e.g., air) to increase the buoyancy of tracking device  102 . Chambers  330  are sufficiently large that tracking device  102  will float in water even when detached from PFD  200  ( FIG. 2 ). In addition, because chambers  330  are disposed near the top of tracking device  102 , GPS antenna  320  and GSM antenna  322  will remain upright when tracking device  102  is floating. Because encapsulation material  328  can cause tracking device  102  to float, encapsulation material  328  is also considered to be a buoyant component coupled to tracking device  102 . 
         [0054]    A hole  332  is defined by encapsulation material  328  to allow for the connection of a device such as a lanyard to aid in the carrying of tracking device  102  when it is separated from buoyant device  200 . 
         [0055]      FIG. 3B  is a side view of the tracking device  102  of  FIG. 3A . In  FIG. 3B , hole  332  is shown to completely pass through the encapsulation material  328 . Additionally, indicator LEDs  324  are shown to be just below the surface of encapsulation material  328 , to ensure that they are visible to the user. Battery  336  is also shown in  FIG. 3B , and is positioned on the same side of circuit board  312  as indicator LEDs  324 . Inductive charging unit  334  is disposed on the opposite side of circuit board  312 . 
         [0056]      FIG. 4A  is a side view of a container  400  for use with tracking device  102  when tracking device  102  is separated from buoyant device  200  of  FIG. 2 . Container  400  includes a body  402 , a lid  404 , a latch  406 , a hinge  408 , and a carrying strap  410 . Container  400  is a waterproof, buoyant container, and is constructed of a non-corrosive material such as plastic. Body  402  of container  400  is shaped to receive and hold tracking device  102  snuggly therein. Body  402  also includes a protrusion  412  for engaging latch  406 . 
         [0057]    Lid  404  of container  400  includes an integrally formed latch  406 . Lid  404  fits tightly over the opening of body  402  and is secured in place by latch  406  engaging protrusion  412 . When latch  406  is properly secured over protrusion  412 , a watertight seal is formed between lid  404  and body  402  of container  400 , as will be described in greater detail below. 
         [0058]    Hinge  408  is a three part hinge comprising a first portion  414 , a second portion  416 , and a hinge pin  418 . First portion  414  of hinge  408  is an integral part of body  402  of container  400 . Likewise, second portion  416  of hinge  408  is an integral part of lid  404 . First portion  414  and second portion  416  of hinge  408  have complementary surfaces with a central aperture for receiving hinge pin  418 . When hinge pin  418  is inserted through first portion  414  and second portion  416  of hinge  408 , and secured in place, lid  404  is pivotally mounted to body  402 . Carrying strap  410  fits between first portion  414  and second portion  416  of hinge  408 , and is attached to container  400  by hinge pin  418 . 
         [0059]      FIG. 4B  is a side cross-sectional view of container  400  with tracking device  102  and an auxiliary battery  420  disposed therein. In this embodiment, auxiliary battery  420  is removable from container  400 , but battery  420  could be permanently molded in the bottom of container  400 . Auxiliary battery contacts  422  are positioned to engage charging contacts  326  of tracking device  102 , and thereby provide auxiliary battery power to tracking device  102 . Auxiliary battery contacts  422  are also used to charge auxiliary battery  420 . Auxiliary battery  420  is charged by inserting a charging adapter (not shown) into container  400  instead of tracking device  102 . 
         [0060]    Contacts  326  of tracking device  102  are held in contact with auxiliary battery contacts  422  by a removable insert  424  that exerts downward pressure on tracking device  102 . Insert  424  also provides an additional watertight seal for the cavity containing tracking device  102 . Insert  424  includes o-rings  428  that fit tightly into complementary grooves on insert  424  and the body  402  of container  400 , thereby holding insert  424  firmly in place. Insert  424  further includes an internal gas chamber  430  to provide additional buoyancy for container  400 . Similarly, lid  404  traps air in the top of container also adding buoyancy to container  400  and making container  400  tend to float in an upright position. 
         [0061]      FIG. 5  is a partially cut-away front view of an alternate PFD  500  having an alternate tracking device  102 A completely embedded therein. In this embodiment, tracking device  102 A is sewn into PFD  500  between an inner layer of fabric  502  surrounding the buoyant material of PFD  500  and an outer layer of material  504 . Tracking device  102 A is held in place by stitching (not shown) and/or an adhesive (also not shown). 
         [0062]    Alternate tracking device  102 A is not directly accessible by the user. Therefore, tracking device  102 A is similar to tracking device  102 , except for a few modifications. In particular, battery  336  and SIM card  314  need not be removable. As a result, tracking device  102 A can be completely encapsulated in encapsulation material  324 . Complete encapsulation provides an advantage in that there is less chance of water leakage into alternate tracking device  102 A. Although inaccessible to the user, alternate tracking device  102 A can be charged via inductive charger  334 . 
         [0063]    The inaccessibility of SIM card  314  is an issue when activating alternate tracking device  102 A. Normally, during the activation of a cell phone type device, the SIM card must be removed in order to read identification information printed on the SIM card. Because SIM card  314  of alternate tracking device  102 A is inaccessible, the required activation information is printed on a tag  506  fixed to PFD  500 . Alternatively, the activation information can be provided on printed material sold with PFD  500 . 
         [0064]      FIG. 6  is a front view of another alternate PFD  600 , including another alternate tracking device  102 B disposed in a pocket  602  of PFD  600 . Pocket  602  is a mesh fabric fixed to the outer layer  604  of PFD  600  and includes an elastic cord  606  and a clasp  608  for securing an opening  610  into pocket  602 . 
         [0065]    PFD  600  further includes permanently embedded auxiliary components. For example, a charging connector  616  and a protective cap  618  are visible in  FIG. 6 . Charging connector  616  is a waterproof connector that facilitates charging of alternate tracking device  102 B when alternate tracking device  102 B is coupled to PFD  600 . Protective cap  618  is a rubber cap that is bonded or sewn to the outer surface  604  of PFD  600  to cover and protect one or more auxiliary antennas ( FIG. 7 ). The types of auxiliary devices that can be attached to PFD  600  are limited to the example auxiliary devices shown. Rather, it is anticipated that many other types of auxiliary devices (e.g., indicator lights, batteries, solar charger, and so on) can be incorporated into PFD  600 . 
         [0066]      FIG. 7  is a partially cut-away front view of PDF  600  showing the electronic interconnection of alternate tracking device  102 B and the auxiliary components. Charging connector  616  is connected to tracking device  102 B via a flexible circuit substrate  700 , which passes between outer layer  604  and an inner layer  701  of PFD  600 . Inner layer  701  is an additional fabric layer below outer layer  604  and functions to separate the tracking device  102 B and the auxiliary components from the buoyant materials disposed below inner layer  701 . Flexible circuit substrate extends from the shoulder area near charging connector  616 , through an opening (not shown) in outer layer  604 , and into pocket  602 . 
         [0067]    Tracking device  102 B connects to flexible circuit substrate as follows. Flexible circuit substrate  700  includes connectors  702  that connect to complementary connectors  702  on another portion of flexible circuit substrate  703  that extends from tracking device  102 . In the view of  FIG. 7 , the connection between flexible circuit substrate  700  and flexible circuit substrate  703  is shown above tracking device  102 B. However, as described above, flexible circuit substrate  700  is sufficiently long to extend into pocket  602 . Tracking device  102 B can, therefore, be connected and disconnected from flexible circuit substrate  700  within pocket  602 , thereby facilitating easy removal and reconnection of tracking device  102 B. 
         [0068]    Flexible circuit substrate  700  further includes an auxiliary GPS antenna  704 , and an auxiliary GSM antenna  706  mounted thereon. GPS antenna  704  and GSM antenna  706  are electrically coupled to tracking device  102  via flexible circuit substrate  700 , connectors  702 , and flexible circuit substrate  710 . GPS antenna  704  and charging connector are housed within protective cap  618 , which is bonded to outer surface  604  of PFD  600 , as previously. A slit in outer layer  604 , beneath protective cap  618 , facilitates the passage of flexible circuit substrate  700  to GPS antenna  704  and charging connector  616 . 
         [0069]      FIG. 8A  is a front view of alternate tracking device  102 B. Tracking device  102 B is similar to tracking device  102  of  FIG. 3A , except that GPS antenna  320 , GSM antenna  322 , internal gas chambers  330 , and hole  332  have been omitted. GPS antenna  320  and GSM antenna  322  are replaced by flexible circuit substrate  703 , which provides a connection to charging connector  616 , GPS antenna  704 , and GSM antenna  706 , via connectors  702  and flexible circuit substrate  700 , as described above with reference to  FIG. 7 . 
         [0070]    In alternate tracking device  102 B, flexible circuit substrate  703  is provided instead of antennas  320  and  322 . This provides an advantage in that tracking device  102 B is smaller, lighter, and less expensive to manufacture. However, it should be understood that flexible circuit substrate can be used in addition to antennas  320  and  322 , so that the user has the option of using tracking device  102 B with the auxiliary components of PFD  600  or as a detached, fully functional tracking device. 
         [0071]      FIG. 8B  is a side view of alternate tracking device  102 B. Note that encapsulation material  828  completely surrounds flexible circuit substrate  703 . Flexible circuit substrate is electrically connected to circuit board  812  prior to the encapsulation process. During the encapsulation process, encapsulation material  828  forms a water tight bond to flexible circuit substrate  703 , thereby preventing any water leakage into tracking device  102 B. 
         [0072]      FIG. 9  is a side cross-sectional view of container  400 , with alternate tracking device  102 B disposed therein. In addition, container  400  includes an alternate removable insert  424 A. Alternate insert  424 A is similar to insert  424 , except that insert  424 A is modified to include a GPS antenna  902  and GSM antenna  904 . Insert  424 A also includes a flexible circuit substrate  906  to connect GPS antenna  902  and GSM antenna  904  to tracking device  102 B via connectors  702  and flexible circuit substrate  703 . Note also that insert  424 A defines an internal chamber that traps air. Thus, container  400  provides buoyancy, auxiliary power, and auxiliary antennas for tracking device  102 B. Indeed, container  400  can host other types of auxiliary devices including, but not limited to, light and sound emitting devices. 
         [0073]      FIG. 10  is a flowchart summarizing a method  1000  for manufacturing a buoyant tracking device. In a first step  1002 , a tracking device configured to communicate via a wireless terrestrial communication network is provided. Then, in a second step  1004 , a buoyant component is provided. Next, in a third step  1006 , the tracking device is coupled to the buoyant component. 
         [0074]    The description of particular embodiments of the present invention is now complete. Many of the described features may be substituted, altered or omitted without departing from the scope of the invention. For example, some wireless communication devices (e.g., controller  302  and wireless modem  306 ) can obtain position information exclusively from the particular terrestrial wireless communication link  106  used, so the GPS components (receiver  304  and antenna  306 ) can be omitted. Alternatively, known assisted GPS systems can obtain accurate position information using a GPS signal or a partial GPS signal in combination with information (e.g., a time stamp) from the wireless communication link  106 . As another example, a great variety of buoyant components may be substituted for the example buoyant components (wearable PFD, container, and encapsulation material). Examples of other such buoyant components include, but are not limited to, PFDs for pets, non-wearable PFDs such as throwable cushions, inflatable PFDs, floating keychains, floating garments such as hats, and so on. 
         [0075]    Note also that the detachability aspect of the invention provides advantages in fields other than marine products. For example, tracking device  102  can be detachably coupled to other articles such as shoes and accessories (including, but not limited to, backpacks, suitcases, and briefcases). In one particular embodiment, tracking device  102  is carried in a pocket or pouch on the side of a shoe. Note that in the non-marine applications the tracking device need not be buoyant. 
         [0076]    These and other deviations from the particular embodiments shown will be apparent to those skilled in the art, particularly in view of the foregoing disclosure.