BROADCAST" (W
Contents
1. Distress relay Distress acknowledgment Test call for MF HF only 10 15 20 25 35 40 45 50 55 60 65 6 Radio frequency or channel Display Receive geographical area calls Alarm Optional means for canceling a distress alert In FIG 2A a preferred circuit implementation for the PELS personal unit 10 is illustrated The principal compo nents of the PELS personal unit are a GPS receiver 20 an integrated DSC RF transceiver 21 antennae 22a for DCS reception and transmission and 22b for GPS reception which are external to the personal unit s housing as shown in the outer solid line microprocessor 23 ROM memory 24 RAM memory 25 and a GPS processor 26 The GPS processor 26 and unit microprocessor 23 may be formed as separate IC units or as a single IC The GPS receiver 20 is typically a specialized front end multi channel radio fre quency receiver IC The GPS receiver 20 outputs data used to determine ECEF fixes to the GPS processor 26 The microprocessor 23 performs the final GPS fix calculation and also handles the PELS control functions An example of a preferred microprocessor is a Motorola 6800 series micro processor such as the 68331 but equivalent devices from other manufacturers are also usable Examples of GPS chip sets including a GPS receiver IC and companion GPS DSP IC that are suitable for use in the PELS system are the Sierra chip set available from Trimble Inc Sunnyvale Ca2. Ephemeris data are good for about 4 hours and are updated hourly Almanac data consist of general information regarding all satellites in the constellation and atmospheric data for a determination of RF propagation delays Almanacs have approximate orbital data parameters for all satellites The typical ten parameter almanac describes the satellite orbits over extended periods of time of up to several months and a set for all satellites is sent by each satellite over a period of 12 5 minutes minimally Signal acquisition time on receiver start up can be significantly aided by the availabil ity of current almanac and ephemeris data The approximate orbital data are used to preset the receiver with the approxi 10 15 20 25 30 35 40 45 50 55 60 65 2 mate position and carrier Doppler frequency i e the fre quency shift carried by the rate of change in range to a moving satellite of each satellite in the constellation Ephemeris data consist of detailed orbital information for the specific observed satellite It can take up to 15 minutes to initialize a GPS system if the almanac and ephemeris data are not available or not up to date GPS based locator systems have required individuals to be equipped with a small GPS receiver and a radio to send their latitude and longitude coordinates over the radio This requires the person to have both devices when lost which is unusual for most recreational boating situa
3. and the individual ID code is transmitted with the RF emergency signal to identify the personal unit sending the RF emergency signal to the base station 12 A personal emergency location system according to claim 9 as used for rescue of a person falling overboard from a vessel wherein the personal unit is worn by the person overboard and the base station is installed on the person s vessel 13 A personal emergency location system according to claim 9 wherein the personal unit includes antenna deploy ment means for deploying its GPS and RF antennae above the water 14 A personal emergency location system according to claim 9 wherein the personal unit includes a battery pack and battery power management functions having a control for placing the personal unit in a Receive Only mode after transmitting the RF emergency signal and receiving back an acknowledgment signal from the base station 15 A method of locating a person in distress comprising the steps of providing a small personal GPS unit to be worn by the person having a battery pack with battery power man agement control and a GPS transmitter receiver unit powered by the battery pack for determining GPS location coordinates of the person s position based upon received GPS satellite signals and transmitting an RF emergency signal including the GPS location coor dinates over a predetermined short range activating the personal GPS unit when the person is in an e
4. FIG 3 4 the personal unit in its Activated State block 401 has the GPS subsystem power on the radio subsystem power on the Major Fault indicator light blinking quickly and the CPU clock speed set to full speed The unit then starts processing a new GPS position fix block 402 Upon completion it transmits a distress signal of the last position it recorded the update to the new GPS position fix and current time block 403 It then checks whether its distress signal has been acknowl edged block 406 and if so turns to the Receive Only RPD Mode block 407 If its distress signal has not been acknowledged it clocks a prescribed increasing time inter val block 405 and if the last fix is older than 10 minutes it returns to start processing a new GPS position fix block 402 Referring to the flowchart in FIG 3 5 the personal unit in its Receive Only RPD Mode block 501 has the GPS subsystem power off the radio subsystem power on both Major and Minor Fault indicator lights blinking quickly and the CPU clock speed set to slow speed The unit checks if it has received an Update Request block 502 and also if the manual activation switch has been activated block 503 If either is yes it goes to its Activated State It is to be understood that many modifications and varia tions may be devised given the above description of the principles of the invention It is intended that all such modifications and variations be cons
5. an RF emergency signal with the determined GPS location coordinates and an RF antenna for transmit ting the RF emergency signal generated by the RF trans mitter within a predetermined short range to any nearby entity having an RF transceiver wherein the personal unit has a balloon fillable with lighter than air gas attached to a distal end of a tether attached to the personal unit and the GPS and RF antennae are attached to the tether and to the balloon such that when the balloon is filled with the lighter than air gas upon deployment during an emergency condition the GPS and RF antennae are held aloft from the person for proper functioning in receiving GPS satellite signals and sending RF emergency signals 7 A personal emergency location system according to claim 6 wherein the antennae are carried within a plastic sleeve attached to the tether and the antennae have ends carried on the inside of the balloon 8 A personal emergency location system according to claim 6 wherein the balloon is dyed a fluorescent color to serve as a visual marker to rescue personnel 9 A personal emergency location system comprising a small personal unit adapted to be worn by a person and having a GPS antenna for reception of GPS satellite signals a GPS receiver for handling the GPS satellite signals a GPS processor for determining GPS location coordinates from the received GPS satellite signals an RF transmitter for generating an RF emergency si
6. and receiving digitized data concerning general broadcasts and distress signals DSC equipped radios are classified as to their frequency band of operation and their inherent capa bility The classifications are listed as Class A G The preferred PELS system uses GMDSS channel 70 for marine applications Channel 70 DSC is the new interna tional emergency frequency and will be required by all Safety Of Life At Sea SOLAS ships by the year 2000 Channel 70 operates in the VHF band at 156 525 MHz and will be monitored by all vessels carrying GMDSS DCS This includes all international rescue agencies and all SOLAS regulated vessels engaged on international voyages except cargo ships less than 300 gross tonnage ships of war and troopships ships not propelled by mechani cal means wooden ships of primitive build pleasure yachts not engaged in trade fishing vessels and ships being navigated within the Great Lakes of North America However it is generally assumed that most commercial and recreational boaters that do not fall under the SOLAS regulations will also choose GMDSS radio equipment to maintain compatibility and utilize the installed base of radio equipment thereby providing the PELS system with a broad base of potential rescuers The basic operation of this invention is simple but requires a unique combination of GPS reception radio transmission and reception power management and antenna design The core of the system is the sm
7. and calculation portion can be shut down until another fix is required by the base station or at prescribed longer intervals such as every ten minutes The re acquisition GPS fix time 10 15 20 25 30 35 40 45 50 55 60 65 8 should be very short less than 15 seconds since the ephemeris and almanac data are already stored in memory The PELS personal unit can be attached to the person s belt or shoulder or held in a pocket However to system s antennas must be held out of the water This can be done by holding the system up attaching it to a hat attaching it to the collar of a life jacket or by the use of a small inflatable balloon holding the antennas aloft as shown in FIG 1 For this purpose a balloon on a tether mounting the antennae can be inflated by a helium capsule and released upon activation The balloon for example would not need to be larger than 18 inches in diameter to support antennae of the contemplated size The balloon could also serve as a better visual target and or as an additional flotation device when at sea In FIG 2B the base station 18 includes a GPS system 40 a computer 41 and a DSC RF transceiver 42 The base station is essentially a computer terminal coupled with a GPS system and a DSC radio transmitter and receiver station The base station can be a stand alone system or interfaced into an existing computer package using PELS software Existing GPS units can be ada
8. is 56 References Cited updated with the most current GPS data and recharged U S PATENT DOCUMENTS during inactive periods when the person on board a vessel equipped as a base station The personal unit sends the 4 219 819 8 1980 Patel ccccccssssssssssssssecseeesessen 116 210 emergency signal until an acknowledgment signal is 5 119 101 6 1992 Barnard 5 191 792 3 1993 Gloor 5 408 238 4 1995 Smith woes 342 357 09 5 420 592 5 1995 Johnson 5 552 794 9 1996 Colley et al 5 815 126 9 1998 Fan et al 5 862 511 1 1999 Croyle OTHER PUBLICATIONS Keeping Tabs On Criminals J Hosen et al IEEE Spec trum Feb 1995 received from a base station whereupon the personal unit is placed in a Receive Only mode to save battery power The base station is equipped with a GPS system that can be updated with the most current GPS data so that it can calculate an accurate vector of approach to the person s position The PELS system handles communications in the preferred GMDSS DSC signal format as defined by the International Maritime Organization 20 Claims 7 Drawing Sheets BROADCAST SIGNAL U S Patent Apr 24 2001 Sheet 1 of 7 US 6 222 484 B1 COMPUTER 40 40a GPS 18 SYSTEM 44 DSC RF Aes BROADCAST SIGNAL A8 FIG 2B U S Patent Apr 24 2001 Sheet 2 of 7 US 6 222 484 B1 GPSL1 VHF Antenna Antenna GPS Digital Signal 10 Main Equipment Housing Figure 2
9. 70 The GPS satellite signals are input to the GPS receiver 20 and the DSC RF signals are passed to from the radio transceiver circuit 21 Antenna design and placement is important for signal reception and transmission The radio circuit design will include both transmitter and receiver circuits for sending receiving a digitized transmission The PELS personal unit power supply includes a main battery 31 and a backup battery 33 The main battery supplies power to the power supply circuitry 32 which converts and regulates the voltage as appropriate for the PELS operational circuitry The main battery pack prefer ably comprises rechargeable or secondary batteries and can be nickel metal hydride lithium or other similar high density commercially available battery An external plug or jack 31 a is provided to allow a recharger line to be connected to the main battery pack 31 The main pack needs to provide power to the system for up to 5 minutes of transmit time and 3 days of receive time plus GPS reception and calculations Transmit time of 5 minutes translates to up to 600 separate transmissions of encoded digital data The backup battery 33 provides power to the RAM which maintains the GPS almanac ephemeris data and current fixes The backup battery can be a very small lithium coin cell battery or similar battery This invention includes several important power conser vation features which allow the device to be made small enough to be worn b
10. A U S Patent Apr 24 2001 Sheet 3 of 7 US 6 222 484 B1 Dormant State Flowchart Figure 3 1 101 Set Maximum Power Conservation a GPS subsytem power off b Radio subsystem power off c Indicator Lamp Green blink slowly d CPU clock speed to minimum 103 If unit in night stand go to Download Update 102 If switched on go to Activated 104 Is battery charge gt 80 Set Indicator Lamp Red to blink slowly 106 Are GPS data files valid ephemeris lt 4hrs 107 If ephemeris gt 3 hrs attempt every 5 minutes Dormant Update 109 Set Indicator Lamp Red to be on continuously 108 Do system diagnostics tests pass U S Patent Apr 24 2001 Sheet 4 of 7 US 6 222 484 B1 Dormant Update Flowchart Figure 3 2 201 Set System for GPS Update a GPS subsytem power on b Radio subsystem power off c Indicator Lamp Green blink quickly d CPU clock speed as appropriate for GPS processing 203 Set GPS subsystem power off Are GPS RF signals Present 204 Download and save latest Almanac and Ephemeris data sets from available GPS satellites Calculate and record current Position and Time datum 205 Return to Dormant U S Patent Apr 24 2001 Sheet 5 of 7 US 6 222 484 B1 Download Update State Flowchart Figure 3 3 301 Set System for GPS Download a GPS subsytem pow
11. a United States Patent Seiple et al US006222484B1 10 Patent No 45 Date of Patent US 6 222 484 B1 Apr 24 2001 54 PERSONAL EMERGENCY LOCATION SYSTEM 76 Inventors Ronald L Seiple 1063 Koohoo PL Kailua Oahu HI US 96734 Robert B Seiple 12319 Calle Albara 3 El Cajon CA US 92017 Notice Subject to any disclaimer the term of this patent is extended or adjusted under 35 U S C 154 b by 0 days 21 Appl No 09 334 859 Get A Grip editor Boating World Jun 1999 cited by examiner Primary Examiner Daniel T Pihulic 74 Attorney Agent or Firm Leighton K Chong 57 ABSTRACT A personal emergency location system PELS employs a small battery powered personal unit worn by a person who may be lost overboard The personal unit has a GPS receiver and processor for determining the person s GPS location 22 Filed Jun 16 1999 coordinates and an RF transmitter for sending an RF Sty nC ee eo H048 7 185 Cmegency signal with the GPS coordinate data to a nearby vessel within a short range The nearby vessel is equipped as 52 U S O E RE EEEE TRA 342 357 09 a base station to receive the RF emergency signal and the 58 Field of Search 00 0 342 357 09 340 573 6 person s GPS coordinate data and send out an RF broadcast 340 984 701 213 116 210 signal of the person s position over a long range to the authorities or other rescue vessels The personal unit
12. al purposes such as by hikers and explorers The PELS personal unit also has a serial interface port 29 for data exchange when connected on board with the base station GPS system described below Activation switch es 30 is provided to give the user manual input capability for example to activate the unit and initialize the distress sequence to exit the RPD mode re send the distress signal manually and or to cancel the distress sequence A number of data busses interconnect the components of the PELS personal unit The ROM 24 and RAM 25 are in data communication with the GPS processor 26 and the microprocessor 23 The GPS processor 26 is in data com munication with the GPS receiver 20 the microprocessor 23 and the ROM 24 and RAM 25 circuits The micropro US 6 222 484 B1 7 cessor 23 is in communications with the GPS processor 26 ROM 24 RAM 25 and the RF transceiver 21 The micro processor is also in communications with the following external components serial data interface 30 indicator lights 29 and activation switch es 30 Address busses also connect the microprocessor 23 and GPS processor 26 to the ROM and the RAM The GPS processor 26 controls the GPS receiver 20 through receiver control lines The PELS antenna 22b receives radio frequency RF signals from GPS satellites on their L1 transmission frequency and the antenna 22a is for reception transmission of GMDSS DSC radio signals at 156 525 MHz Channel
13. al unit can be re activated by the lost person at anytime even when placed in the RPD mode by the base station The PELS personal unit is preferably configured for classification of DSC Class F devices which operate on VHF band but cannot make an individual or routine call and does not require a display Class F required capabilities include Distress call All ships call Use of distress urgency and safety priorities Distress coordinates Time for last distress position update Receive individual station call Receive acknowledgment of its own distress calls Since the PELS personal unit s transmission is based on the standard GMDSS DSC protocol all GMDSS DSC radios can receive the distress call and its associated positional information This will provide the distressed individual the widest possible dissemination of the radio distress signal allowing any and all DSC radio equipped vessels to receive and process the distress signal and assist in the rescue operation The PELS base station is preferably configured to DSC requirements for Class B devices Class B devices operate via VHF and MF radios used by SOLAS regulated ships and required capabilities include Distress call All ships call Individual station call Semi automatic automatic service call Use of distress urgency safety and routine priorities Nature of distress Distress coordinates Time for last distress position update Type of subsequent communications
14. all personal unit worn by individuals Once activated the small personal unit calculates its position using a GPS receiver and sends that position by RF to a base station For marine applications the RF signal uses the GMDSS DSC frequency of 156 525 MHz This signal is sent in a digitally coded data packet format as specified by the IMO to meet all GMDSS DSC requirements It sends these bursts at specific time intervals with a decreasing repetition rate calculated to optimize the trade off between operational life span and limited battery capacity Once the personal unit s signal is received by a base station the base station translates that signal into a GPS location and the individual s ID code The ID code will identify the signal to a specific individual and ship For rescue operations this is extremely important as it will reduce false alerts to a minimum by allowing rescue opera tions to determine if the situation is real or not Once the base station receives the information it sends a DSC Acknowledgment Signal to the personal unit When the personal unit has received the acknowledgment signal it goes into a receive only mode RPD mode The base station or any other base station can re activate the personal unit at any time or it can be commanded by the individual wearing the unit In the later case if a new aircraft or surface vessel comes nearby the personal unit may be turned on to notify that new vessel Upon receivin
15. ation is only accurate to within sev eral square miles and can be off as much as thirty square miles Other rescue locating devices include mirrors strobes and lights whistles flares and other items These are certainly better than nothing but they are not ideal In many instances these devices must be operated by the overboard person who may quickly be overcome and incapacitated by the environ ment More recently Global Positioning Systems GPSs have been used to locate lost persons GPS systems determine position by receiving signals from a sub set of the 24 U S GPS satellites that are in operation The signals transmitted by each satellite include a time code which is synchronized with the time codes transmitted by the other satellites The GPS system calculates an earth centered earth fixed ECEF position for the location where the signals are received based on the time differences between the signals received from the satellites and the known location of the satellites ECEF positioning uses a 3 axis coordinate system with the origin located at the center of the earth and can be translated to a global coordinate based system i e latitude and longitude The GPS satellites are not in geo synchronous orbits The location of the satellites are determined from almanac and ephemeris data either downloaded from the ship s host system or from the satellites themselves Almanac data are good for several weeks and are updated weekly
16. based system on board the person s vessel or a nearby vessel referred to US 6 222 484 B1 3 as the base station that is able to receive the distress signal from the PELS personal unit and provide a distress acknowledgment to it The base station translates the received personal unit s GPS position into its own naviga tion program and calculates an intercept vector range and bearing to the individual or plots the location of the individual on an electronic chart The base station can have an emergency communications system which will receive the distress signal and alert the operator with the overboard person s positional information The base station can per form a Distress Relay to other appropriate authorities as defined by the IMO Upon receipt of the Distress Acknowledgment the personal unit will enter a standby mode to preserve battery power and enable an acknowledgment received indication for the distressed indi vidual This can be done by use of an indicator light s audible signal or vibration The lost person thus knows by the indicator that his distress signal has been received The present invention also encompasses the related method for determining the exact location of lost persons equipped with a PELS personal unit whether on ocean or land BRIEF DESCRIPTION OF THE DRAWINGS The features objects and advantages of the invention will be described in detail below in conjunction with the acc
17. er off b Radio subsystem power off c Indicator Lamp Green blink quickly d CPU clock set to full speed 303 Upload fault status to host Were hardware faults present Wait until battery pack is fully charged 305 Download and save latest Almanac and Ephemeris data sets and current Position and Time datum from host syste 306 Return to Dormant U S Patent Apr 24 2001 Sheet 6 of 7 US 6 222 484 B1 Activated State Flowchart Figure 3 4 401 Set System for Distress Transmittal a GPS subsytem power on b Radio subsystem power on c Indicator Lamp Red blink quickly d CPU clock set to full speed 402 Start processing new GPS position fix Turn GPS power off when complete Yes 403 Transmit Distress signal with position and time from last download update to new GPS position fix and time when GPS Receiver has processed new fix Is last fix older than 10 min 405 Wait for prescribed interval Interval period increases at a prescribed rate to preserve battery power while still in Activated mode Has Distress been Acknowledged Yes 407 Go to Receive Mode RPD U S Patent Apr 24 2001 Sheet 7 of 7 US 6 222 484 B1 Receive Mode RPD State Flowchart Figure 3 5 501 Set System for Radio Receive mode a GPS subsytem power off b Radio receiver subsystem power on c Indicator Lam
18. es the person s GPS location coordinates The PELS personal unit will start emitting its initial Distress Call transmission s after activation The unit s RF transmitter sends an RF emergency signal with the GPS location data over a short range line of sight from the battery powered unit Depending on the transmitter power level chosen and the placement height of the antenna this short range can be anywhere from 3 to 15 or 20 miles The person s vessel or a nearby vessel within the short range the base station can receive the RF emergency signal and send a broadcast 10 15 20 25 30 35 40 45 50 55 60 65 4 signal over a longer range and at higher power to other rescue vessels emergency communications stations such as a USCG station or even to a satellite receiver for relay In a preferred embodiment of the invention the base station vessel is equipped with a GPS system and a Global Maritime Distress and Safety System GMDSS radio which is defined by the International Maritime Organization IMO and the United States Coast Guard USCG as the next generation of maritime radio communications GMDSS defines the use of maritime radio systems and specifically defines the digitized distress signaling capability of stan dardized maritime systems called Digital Selective Calling DSC DSC is implemented on each radio frequency band MF HF and VHF as a single channel for transmitting
19. g a DSC Individual Station US 6 222 484 B1 5 Call with its own ID code as the intended recipient the PELS personal unit will begin retransmitting its Distress Call until another Distress Acknowledgment signal is received whereupon it goes back into RPD mode This technique saves on battery power for the personal unit Since any base station can command an updated position of the personal unit any GMDSS DSC equipped ship or aircraft could determine the position and effect a safe recovery The PELS personal unit can thus provide GPS signals of the person s exact location to the base station using DSC radio signals Unlike other current systems that use RF DF to locate someone this system provides the more accurate GPS calculated position of latitude and longitude in tenth of seconds The base station then uses the lat long information to determine the exact position of the distressed individual which can be displayed electronically on a chart or map or provided in vector format bearing and distance from the rescuing platform s current position to effect a recovery The personal unit must be able to receive GPS and DSC frequencies at all times This is accomplished by using a specially protected antennae that can operate in a wet environment e g sheathed in a balloon The personal unit can be activated either automatically e g by an immersion sensor when it becomes wet or manually by the person The person
20. gnal with the determined GPS location coordinates and an RF antenna for transmit ting the RF emergency signal generated by the RF trans mitter within a predetermined short range to any nearby entity having an RF transceiver wherein the nearby entity is a base station having a GPS system for receiving GPS satellite signals and updated almanac and ephemeris data an RF transceiver for receiving an RF emergency signal with determined GPS location coordinates from the personal unit a 15 20 25 30 35 40 45 50 55 60 65 12 computer for computing the person s position on the basis of the determined GPS location coordinates from the personal unit and the updated GPS data received by its GPS system and emergency alert means for sending an RF broadcast signal of the person s position over a long transmission range wherein the personal unit and the base station have interconnection means for transmitting updated GPS data from the base station to the personal unit so that the personal unit can be updated with the updated GPS data 10 A personal emergency location system according to claim 9 wherein the interconnection means comprises an individual recharge module connected to the base station to which the personal unit is connected during inactive periods 11 A personal emergency location system according to claim 9 wherein the personal unit is assigned an individual ID code recognized by the base station
21. harged if it has dropped to the 80 power remaining level Since the system does not become fully operational while on board the ship recharging can take some time The module 50 can be configured as a remote unit into which the personal unit is plugged or inserted in its night stand when the user is asleep The personal unit can thus be recharged to 100 level and updated with ephemeris almanac position and time data on a daily basis Besides managing the GPS system with navigation mapping package and the DSC RF transceiver the base station can have automatic alert and transmission functions for automatically displaying an alert and sending a broadcast signal when an emergency signal is received from a personal unit The alert software can have an automatic alarm func tion that comes on and provides an audible signal The base station can be set up to automatically monitor channel 70 on DSC This DSC channel will be monitored at all times like 121 7 or channel 16 is currently monitored When a DSC US 6 222 484 B1 9 distress signal is received from a PELS personal unit the base station s DSC radio will recognize the signal as an emergency and the pertinent data is recorded on the system computer The software then determines the position and the ID of the personal unit initializes the alert and sends out an acknowledgment message to the personal unit The personal unit is then switched into the RPD mode If the RPD mode is n
22. idered as within the spirit and scope of this invention as defined in the following claims What is claimed is 1 A personal emergency location system comprising a small personal unit adapted to be worn by a person and having a GPS antenna for reception of GPS satellite signals a GPS receiver for handling the GPS satellite signals a GPS processor for determining GPS location coordinates from the received GPS satellite signals an RF transmitter for generating an RF emergency signal with the determined GPS location coordinates and an RF antenna for transmit ting the RF emergency signal generated by the RF trans mitter within a predetermined short range to any nearby entity having an RF transceiver which can receive the short range RF emergency signal and send an acknowledg ment signal to the personal unit and wherein the personal unit includes a battery pack and battery power management functions having a control for placing the personal unit in a Receive Only mode after transmitting the RF emergency signal and receiv ing back the acknowledgment signal from the nearby entity 2 A personal emergency location system according to claim 1 further comprising the nearby entity as a base station having a GPS system for receiving GPS satellite US 6 222 484 B1 11 signals and updated almanac and ephemeris data an RF transceiver for receiving an RF emergency signal with determined GPS location coordinates from the personal uni
23. itter for generating an RF emergency signal with the determined GPS location coordinates and an RF antenna for transmitting the RF emergency signal gen erated by the RF transmitter within a predetermined short range 15 activating the personal unit when the person is in an emergency condition and transmitting the RF emer gency signal with the determined GPS location coor dinates generated by the RF transmitter 20 receiving the RF emergency signal with the determined GPS location coordinates at a nearby entity equipped with an RF transceiver and sending an RF broadcast signal of the person s position based on the determined GPS location coordinates over a long transmission range 14 wherein the transmitting step includes continuing to send the RF emergency signal at increasingly longer time intervals until an acknowledgment signal is received by the personal unit and thereupon placing the personal unit in a Receive Only mode 18 A method of locating a lost person according to claim 17 wherein the personal unit is re activated from the Receive Only mode when an update request signal is received or by manual activation 19 A method of locating a lost person according to claim 17 wherein the personal unit sends and receives emergency communication signals according to specifications for GMDSS DSC radio communications 20 A method of locating a lost person according to claim 17 used for a person lost overboard from a ves
24. lif the Sirfstar chip set available from Sirf Technology Inc Sunnyvale Calif or similar chip sets available from Garmin Inc Olathe Kans The PELS personal unit also includes a crystal oscillator circuit 27 that provides clock and local oscillator signals to the GPS processor 26 GPS receiver 20 and microprocessor 23 The clock circuits may also contain a Real Time Clock to maintain the time standard while in sleep or power down modes Standard computer read only memory ROM 24 is used to permanently store the PELS software requirements Standard random access memory RAM 25 is used to temporarily store ephemeris data almanac data and other operands To save on bulk and weight the PELS personal unit is shown without a data display Instead it can have indicator lights 28 to show its operational status The indicator lights can have multiple modes to alert the user to the following conditions 1 activated all systems are on activation has occurred and distress signals are being sent 2 acknowledged distress signals have been sent and acknowledgment has been received and the RPD mode is set 3 minor fault for example the almanac data has expired so the GPS will take longer to process a fix or the main battery pack has discharged to below 80 etc and 4 major fault the unit is not functioning properly A data display may be an option for certain applications in which the system is being used for information
25. mergency condition such that the battery pack powers the transmitting of the RF emergency signal with the person s GPS location coordinates receiving the RF emergency signal with the person s GPS location coordinates from the personal GPS unit at a nearby rescue entity equipped with an RF transceiver and sending an acknowledgment signal back to the personal unit using the battery power management control to place the personal GPS unit in a Receive Only mode when the acknowledgment signal is received by the personal GPS unit in order to conserve battery power in the battery pack and activating the personal GPS unit again from the Receive Only mode to transmit another RF emergency signal when a location update request signal is received or upon manual activation of the personal GPS unit 16 A method of locating a person in distress according to claim 15 further comprising assigning an individual ID US 6 222 484 B1 13 code to the personal GPS and sending the individual ID code with the RF emergency signal transmitted from the unit in order to identify the personal GPS unit 17 A method of locating a person in distress comprising the steps of 5 providing a small personal unit to be worn by the person having a GPS antenna for receiving GPS satellite signals a GPS receiver for handling the GPS satellite signals a GPS processor for determining GPS location coordinates the received GPS satellite signals an RF 10 transm
26. nitors if it passes its diagnostic tests block 108 and if not sets its Major Fault red indicator light to be on continuously Referring to the flowchart in FIG 3 2 the personal unit in its Dormant Update Procedure block 201 has the GPS subsystem power off the radio subsystem power off the Minor Fault green indicator light blinking quickly and the CPU clock speed set for GPS processing If GPS signals are input block 202 the personal unit downloads the latest almanac and ephemeris data from the available GPS satellite 10 15 20 25 30 35 40 45 50 55 60 65 10 transmission signals and records the current position and time data block 204 If not the GPS subsystem is shut off block 203 and the unit returns to the Dormant state block 205 Referring to the flowchart in FIG 3 3 the personal unit in its Download Update Procedure block 301 has the GPS subsystem power off the radio subsystem power off the Minor Fault indicator light blinking quickly and the CPU clock speed set to full speed If hardware faults are detected block 302 the personal unit uploads its fault status to the host base station block 303 If not it tests whether the battery pack has been fully charged block 304 and also downloads the latest almanac and ephemeris data and records the current position and time data block 305 The unit then returns to the Dormant state block 306 Referring to the flowchart in
27. ns system such as maintained by the Iridum Satellite Consortium Similarly a signal relayed by satellite could be used to signal the PELS personal unit or to signal a nearby base station to signal the PELS personal unit The satellite system can be used as a relay to send out an alert over the DSC network or otherwise to alert vessels within the vicinity By tying into a global satellite relay system the PELS system can be used any where on land or sea although it would require a higher cost and higher demands for system capability The preferred modes of operation of the PELS system will now be described Referring to the flowchart in FIG 3 1 the personal unit in the dormant state block 101 has the GPS subsystem power off the radio subsystem power off its Minor Fault green indicator light blinking slowly and the CPU clock speed set to minimum If switched on block 102 the personal unit goes to its Activation Procedure If the unit is inserted in its night stand block 103 it goes to its Download Update Procedure Otherwise the unit moni tors if the battery charge is below 80 block 104 and if so sets its Major Fault red indicator light to blink slowly block 105 to inform the user that the unit needs to be recharged in its night stand The unit also monitors if the ephemeris data have not been updated for more than 4 hours block 106 and if so attempts to go to its Dormant Update Procedure block 107 The unit also mo
28. om panying drawings in which like reference numerals desig nate like parts throughout wherein FIG 1 is a diagram of use of the personal emergency location system PELS including the personally worn device and the base station in accordance with the invention FIG 2A is a diagram showing the components of an embodiment of the personal PELS unit and FIG 2B is a diagram illustrating the components of the base station FIGS 3 1 3 2 3 3 3 4 and 3 5 are flowcharts illustrating the sequence of steps performed by the main program and subroutines used to operate the PELS system DETAILED DESCRIPTION OF THE INVENTION Referring to FIG 1 a personal emergency location sys tem PELS in accordance with the present invention employs a small battery powered personal unit 10 worn by a person fallen overboard and a GPS equipped transceiver system 18 on board the person s vessel or any thus equipped nearby vessel Once overboard the person activates the personal unit 10 to initialize its GPS receiver Preferably activation will also inflate and deploy a balloon 12 which holds an antenna 14 for the personal unit above the water The antenna may be carried within a plastic sleeve line and on the inside of the balloon The balloon may also be dyed a fluorescent color to serve as a visual marker to rescue personnel The personal unit s GPS receiver receives the available GPS satellite transmission signals and its processor deter min
29. ot activated the base station will quickly know because the personal PELS will keep responding until it is placed in the RPD mode Once the system is in the RPD mode any vessel equipped with a PELS base station can request an updated position by sending a predetermined signal to the personal unit such as the standard GMDSS DSC Indi vidual Station Call When the Individual Station Call is received by the personal unit it is re activated to update its GPS position and retransmit the DSC distress signal It continues to transmit the update until it receives an acknowl edgment signal whereupon it returns to the RPD mode This process continues until a rescue is accomplished If the PELS personal unit remains in the RPD mode longer than a preset amount of time and the unit is not de activated or has not received an Individual Station Call the PELS personal unit can be programmed to auto matically retransmit the Distress Call This feature may be useful in conditions where the person in distress is uncon scious or disabled The PELS system may be used to send an emergency alert directly or indirectly to a satellite receiver With sufficient battery power and antenna range the PELS personal unit can be used to send a signal directly to a satellite receiver in the same way as a base station alert or indirectly via a nearby base station For example the PELS system could send an alert to a global satellite telecommunicatio
30. ps Red amp Green blink slowly d CPU clock set to slow speed Has radio received an update request Has operator manually re activated the system 504 Go to Activated Mode US 6 222 484 B1 1 PERSONAL EMERGENCY LOCATION SYSTEM FIELD OF INVENTION The present invention relates to a system and method for locating a person lost overboard from a vessel More particularly the invention concerns a system that is attached to the person at all times while at sea and operates to signal the person s exact location to the vessel or to other rescue vessels BACKGROUND OF THE INVENTION For years persons have been lost overboard and not been able to be located even when near their own ship Although Emergency Position Indicator Radio Beacons EPIRBs have been widely used for decades they have not been sufficiently small enough to be carried by individuals Additionally EPIRBs use radio frequency direction finding and therefore are not very accurate in pin pointing an individual or even a small boat lost at sea They are not even very effective for allowing the person s ship to locate the person who has fallen overboard EPIRBs are typically used by the United States Coast Guard USCG service which continually monitors for EPIRB emergency radio broadcasts and have the ability to determine the location of the EPIRB by Doppler signal processing from the satellite receivers An EPIRB determined loc
31. pted to this system It is desirable to have a computer with output video display to provide a chart or map position of the lost person This can be done by connecting a laptop computer or the components can be integrated in a PELS base station system The computer 41 can be used to interface to computerized chart display software or systems and shipboard automatic piloting systems The GPS ephemeris data can be kept precise with updates every 4 hours If the ephemeris data are older than four hours the first GPS fix can take up to 5 minutes to obtain The personal unit can update the ephemeris data in two ways The first method is to download the data from the base station during sleep periods while recharging the batteries The second method is to update the personal unit with its GPS receiver whenever the GPS signals are available for reception The on board GPS system of the base station can be configured with the ability to transfer GPS almanac and current ephemeris data to the individual PELS units during sleep periods via a serial interface circuit 40a The serial interface circuit 40a is connected to separate recharge mod ules 50 to which the PELS units are connected during inactive periods for data transfer and recharging the main battery When connected with the on board GPS system each personal unit can download the GPS updated almanac and current ephemeris data and perform functional tests In addition the main battery pack is rec
32. s GPS location coordinates and an RF transmitter for sending an RF emergency signal of the person s coordinate data to a nearby vessel such as the person s vessel within a short range The PELS personal unit is updated with the most current ephemeris data during a time when the person is inactive on board the vessel by plugging it into an input module connected with the vessel s GPS system The person wears the PELS personal unit when on active duty on the vessel If the person falls overboard the PELS personal unit is activated to send an emergency signal with the person s location coordinates The person s vessel or a nearby vessel within a short range can receive the PELS emergency signal provide a distress acknowledgment mark the position of the person based on the received emergency signal and broad cast an alert and emergency signal to other rescue vessels or stations of the person s position In a preferred embodiment of the present invention the PELS personal unit includes a ROM memory for storing a GPS calculation program of machine readable instructions in order to determine the person s GPS location coordinates to be sent via radio frequency to a nearby GPS equipped vessel The RF signal is preferably formatted as a digitized data packet transmitted at 156 525 MHz meeting all Inter national Maritime Organization IMO specifications for digital emergency radio communications The PELS system also requires a GPS
33. sel wherein the receiving step includes equipping the vessel with a GPS system for receiving updated GPS data and updating the personal unit while the person is on board the vessel and with an RF transceiver for receiving the RF emergency signal from the personal unit when the person has fallen overboard and sending the RF broadcast signal of the person s position
34. t a computer for computing the person s position on the basis of the determined GPS location coordinates from the per sonal unit and the updated GPS data received by its GPS system and emergency alert means for sending an RF broadcast signal of the person s position over a long trans mission range 3 A personal emergency location system according to claim 2 as used for rescue of a person falling overboard from a vessel wherein the personal unit is worn by the person overboard and the base station is installed on the person s vessel or other nearby vessel 4 A personal emergency location system according to claim 1 wherein the personal unit includes a GPS processor paired with the GPS receiver for calculating GPS location coordinates from the received GPS satellite signals 5 A personal emergency location system according to claim 1 wherein the battery pack and battery power man agement functions have a control for activating the GPS receiver and RF transmitter only after receiving an activa tion signal from a sensor detecting an emergency condition or upon manual activation 6 A personal emergency location system comprising a small personal unit adapted to be worn by a person and having a GPS antenna for reception of GPS satellite signals a GPS receiver for handling the GPS satellite signals a GPS processor for determining GPS location coordinates from the received GPS satellite signals an RF transmitter for generating
35. tions and typi cally only occurs with military pilots who are thus equipped Another approach has been to carry a device that sends an RF emergency signal to the person s vessel or a nearby vessel when overboard so that the crew on the vessel can broadcast an alert of the overboard situation and give at least the vessel s location with its on board GPS navigation system when the emergency signal is received This would provide rescue vessels with the position of the vessel from which the person has fallen overboard but cannot provide the exact location of the person nor an update of the person s location adrift with the current A person overboard in heavy sea often cannot be seen even one hundred feet away from a pending rescue vessel If rescue is not accomplished quickly that person can easily be lost Larger ships and sailing vessels typically take time to turn around and retrace their course so not having an exact location of the overboard person can greatly diminish the effectiveness of the rescue effort In small sailing vessels often only one person is on watch if that person falls overboard it may be hours before it becomes known SUMMARY OF THE INVENTION In accordance with the present invention a personal emergency location system PELS comprises a small battery powered personal unit adapted to be worn by a person who may have fallen overboard from a vessel having a GPS receiver and processor for determining the person
36. y an individual These features include the GPS receiver IC and the GPS processor IC being placed in the standby mode or sleep mode between the times that the signals are received from the GPS satellites to obtain a fix Power is conserved by reducing the clock rate of the microprocessor during periods of GPS shutdown The microprocessor is operated at its full clock rate only while performing calculations related to obtaining a GPS fix The operating speed of the microprocessor is varied by changing the frequency of the programmable Phase Lock Loop PLL that provides the clock input to the microprocessor Alternatively some models of microprocessor have internal systems for clock speed modulation DSC transmissions are repeated at decreasing time intervals until a Received Acknowledgment signal is registered then the DSC trans mitter is placed into sleep mode until either an Update Request is received via DSC or the user re activates the distress switch Reduction in power consumption permits less battery volume which results in a smaller overall size and weight of the PELS personal unit Satellite reception time for receiving signals for a GPS fix can be reduced to an absolute minimum by maintaining up to date almanac and ephemeris data The worst case for an initial GPS fix by the personal unit would be approxi mately 3 4 minutes no valid ephemeris or almanac data present Once the initial fix is acquired the GPS reception
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