Understanding Smart Sensors - Nomads.usp

192 Understanding Smart Sensorsa transmission that enables the logic to store new data into the onboard memory.The charge pump increases the 2V to 15V to reprogram the EEPROM.RF-ID tags are being used for automatic toll collection. The driver doesnot have to slow down for the system to detect the vehicle’s ID and debit thedriver/owner’s account. Congestion on highways is reduced and revenue still iscollected to cover road construction and maintenance.8.3.8 Other Remote SensingRF bar code readers, which have become commonplace, demonstrate the freedomof operating untethered for a commercial application. Available RF unitsprovide data from a charge-coupled device (CCD), laser scanner, or infraredwand sensor to a base station that can be up to 150 ft (45.7m) away. The unitsare mobile and can be used without the interference of wires in high-trafficareas.Remote meter reading is being accomplished by transmitting the amountof gas, water, or electricity consumed at a particular site to a mobile receivingunit. A single operator can verify the status of almost twice the number ofaccounts, thereby reducing the cost of the measurement. Remote bar code readersand scanners are also among the applications that are taking advantage ofRF technology in a sensing environment.8.3.9 Measuring RF Signal StrengthExposure, especially continued exposure, is a concern for RF signals. TheAmerican National Standards Institute (ANSI) has limits for equivalent permissibleexposure, depending on the frequency. An RF dosimeter has beendesigned to detect and record the strength and duration of electric fields presentin work areas of naval vessels [26]. The potential to include the electronicsin the already pocket-sized sensor with other RF measurement techniques mayprovide useful data in future applications.8.4 TelemetryTelemetry is a remote measurement technique that permits data to be interpretedat a distance from the primary detector. Telemetry is used in race cars toallow the pit crew to analyze the real-time data generated from a vehicle on thetrack and provide feedback to the driver that can affect the outcome of the race.For example, in Ford’s Formula One system, more than a dozen sensors placedaround the vehicle provide information to the engine control computer and