A device for sensing vehicles and collecting traffic data. A detector may be embedded in the roadway pavement (e.g., inductive loop detector) or placed above the roadway (e.g., passive acoustic detector).
A device used for temperature sensing consisting of a wire coil or deposited film of pure metal for which the change in resistance is a known function of temperature. The most common type is nickel, with other types being copper, platinum, and nickel-iron.
One that detects, especially a mechanical, electrical, or chemical device that automatically identifies and records or registers a stimulus, such as an environmental change in pressure or temperature, an electric signal, or radiation from a radioactive material.
A device providing an electrical output that is a useful measure of incident radiation. It is broadly divisible into two groups: thermal (sensitive to temperature changes), and photodetectors (sensitive to changes in photon flux incident on the detector), or it may also include antennas and film. Typical thermal detectors are thermocouples, thermopiles, and thermistors; the latter is termed a bolometer.
A device that measures the amount of energy radiated by an object. Can be a thermal detector or a photodetector. Thermal detectors respond to radiation by changing their volume, capacitance, or generation of millivoltages; they can be thermocouples, thermopiles, pneumatic detectors, or bolometers. Their common feature is their relatively slow response. Photodetectors are Semiconductors which produce a signal in proportion to the photon flux which strikes them.
portion of the receiver that demodulates the RF NMR signal and converts it to a lower frequency signal. Most detectors now used are phase sensitive (e.g. quadrature demodulator/detector), and will also give phase information about the RF signal.
An electronic device that quantitatively discerns the presence of the separated components as they elute. There are different types of detectors. Some of the common detector types are: UV/Visible light absorbance, differential refractive index, electrochemical, conductivity, and fluorescence.
A device in a radiometer that senses the presence and intensity of radiation. The incoming radiation is usually modified by filters or other optical components that restrict the radiation to a specific spectral band. The information can either be transmitted immediately or recorded for transmittal at a later time.
A passive RF component used to convert an RF power signal into a voltage signal. It is used to supply a voltage, which is proportional to the RF power signal, to another component or piece of test equipment which is not designed to handle an RF power signal.
A detector is a device that recovers information of interest contained in a modulated wave. The term dates from the early days of radio when all transmissions were in Morse Code, and it was only necessary to "Detect" the presence (or absence) of a radio wave using a device such as a coherer; not necessarily making it audible.
A sensor used for the detection of some form of energy. Usually this term is used to refer to the device used in nuclear logging tools to detect neutrons and gamma rays. See scintillation counter and Geiger-Mueller counter.
A circuit that produces a low frequency output signal, typically DC or video, whose amplitude is dependent upon the RF incident power level. The semiconductor element in a detector is typically a Schottky diode, FET or a tunnel diode.