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The LoJack Stolen Vehicle Recovery System is an aftermarket vehicle tracking system that allows vehicles to be tracked by police, with the aim of recovering them in case of theft. The manufacturer claims a 90% recovery rate.〔(【引用サイトリンク】title=What is LoJack )〕 The name "LoJack" was coined to be the "antithesis of hijack", wherein "hijack" refers to the theft of a vehicle through force. LoJack’s core business comprises the tracking and recovery of cars, trucks, construction equipment, commercial vehicles and motorcycles. However, LoJack is expanding into new markets through licensing agreements and investments in areas such as cargo security and people at risk of wandering (probationers, parolees, and Alzheimer's patients). LoJack Corporation claims that over 300,000 vehicles have been recovered worldwide since the product was introduced more than two decades ago.〔 ==How it works== The core of the LoJack Stolen Vehicle Recovery System is a small, silent radio transceiver that is installed in a vehicle. The vehicle is not marked as possessing a LoJack transceiver, and the location of the transceiver within the vehicle varies from one car to the next. Once installed, the unit and the vehicle's VIN are registered in a database which interfaces with the National Crime Information Center (NCIC) system used by federal, state and local law enforcement agencies throughout the U.S. In the event of a theft, a customer reports the incident to the police, who make a routine entry into the state police crime computer, including the stolen vehicle's VIN. This theft report is automatically processed by LoJack computers, triggering a remote command to the specific LoJack unit in the stolen vehicle. The command tells the LoJack unit to start sending out signals to tracking units on board some police cars. Every police car so equipped, that is within a 3–5 mile radius of the signal source, will be alerted. The tracking units will display an alphanumeric serial number and an indication of the approximate direction and distance to the stolen vehicle. Based on the serial number, the police can obtain a physical description of the vehicle, including make (brand), model, color, VIN, and license plate number. Police aircraft can also be equipped with tracking units; airborne units can receive the (line-of-sight) signals from further away than ground-based units. The company’s systems are operable in 29 U.S. states, the District of Columbia, and in 30+ counties.〔http://www.lojack.com〕 Upgraded (more expensive) systems can alert the owner of a vehicle in the event the car is moved or started. LoJack transmits on a radio (RF) carrier frequency of 173.075 MHz. Vehicles with the system installed send a 200 millisecond (ms) chirp every ten seconds on this frequency. When being tracked after reported stolen, the devices send out a 200 ms signal once per second.〔(【引用サイトリンク】title=LoJack Radio Frequency, How LoJack Works )〕 The radio frequency transmitted by LoJack is near the VHF spectrum band formerly used in North America by analog television channel 7,〔(【引用サイトリンク】title=Television Frequency Table )〕 although there was minimal interference due to the low power of radiation, brief chirp duration, and long interval between chirps. The Lojack signal is received in equipped police vehicles utilizing a phased array antenna system, hence the four distinctive antennas on the roof. This provides the direction finding capabilities of the LoJack system. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「LoJack」の詳細全文を読む スポンサード リンク
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