1. Field of the Invention
The present invention relates to a direction and distance estimation system and method based upon characteristics of the Radio Frequency (RF) and the power path loss curve to locate victims.
2. Description of Related Art
Aircraft emergency locator systems such as ELTs (Emergency Locator Transmitters) and terrestrial location systems such as PLBs (Personal Locator Beacons) are well known in the existing art. Individuals lost at sea and fortunate enough to have emergency location identification devices such as an Emergency Position Indicating Radio Beacon (EPIRB), can send out RF signals with the hopes that their distress signals will be picked up by maritime stations or satellites, which can in turn, relay the information to the proper authorities.
Handheld or mobile location devices and systems can effectively locate the directional parameters associated with distress beacons; however, in order to obtain accurate distance readings, one must employ the use of satellites and global positioning systems (GPS). If a distress beacon emits a GPS signal to orbiting satellites, then a searcher may easily locate the distress beacon based upon the GPS reading. Many distress beacons currently being used are not equipped to transmit GPS readings and merely emit a RF signal for reception by a handheld, mobile, stationary or orbiting satellite receiver. As stated above, the RF receivers used to track and locate a RF signal from a distress beacon effectively locate the direction of the beacon, however reliable distance readings under this application are not possible. The lack of distance readings to the beacon can unnecessarily prolong or possibly imperil a search and rescue operation. If an individual is attempting to locate a person lost at sea, then initial movement of a search vessel is carefully monitored in order to prevent possibly running over the distressed victim. If the search vessel is a great distance from the distressed victim, then valuable time may be lost due to the necessity to move slowly during the searching process. If accurate distance readings were available, then the searching process could be shortened and therefore increase the likelihood of a successful rescue.
Directional and distance information may be equally important to search and rescue operations on land. Searchers may need to locate a distress beacon in dense woods or an urban metropolitan area. The beacon may be used by hikers, off road adventurers, skiers, campers and children. If the searcher is limited to directional data only, then even the effectiveness of a land search could be significantly diminished.
Avalanches are a great hazard to skiers, hikers and climbers and other people in mountain regions during winter. If a person is buried by snow, there is a very short period of time available to recover the person before he or she suffocates or dies of exposure due to the snow pack. The time factor in locating someone buried in an avalanche is a critical factor in the survival of the person buried. Electronic locating devices are known in the prior art to find victims of an avalanche that are buried under snow. Avalanche rescue devices manufactured by several companies transmit an RF signal on a frequency of 457 kHz. U.S. Pat. No. 6,031,482 issued to Lemaitre, et al., Feb. 29, 2000, discusses a method and system for sensing and locating a person, e.g. under an avalanche. Various types of electronic systems are discussed in this patent. U.S. Pat. No. 6,167,249 issued to Hereford, et al. discloses an avalanche victim locating transceiving apparatus that uses a plurality of different antennas that are arranged to provide directional and distance estimates to the victim along the lines of flux. None of the references exploit the RF characteristics of the field or power path loss curve to estimate a point to point direction and distance to an avalanche victim.
It would therefore be advantageous to provide a method and system for the location of a distress beacon that would provide the searcher with accurate distance and direction estimations. By providing a searcher with distance and directional estimations, the search time may be reduced significantly without endangering the distress victim. Although, the search and rescue operation has been discussed in association with sea and water rescue, distance estimations are also advantageous in regard to terrestrial search and rescue missions. It would also be advantageous if a handheld device facilitated the operation of the present system and method.