A police scanner is basically a radio scanner that is also a receiver that receives wireless radio signals. A scanner identifies these wireless radio waves. A scanner can identify numerous radio signals and bands concurrently making it easy to keep track of many channels simultaneously. The phrase “police scanner” derives from the fact that the …
A photodetector is a device that imprints the image of an object or scene onto a material. Photodetectors are made in various ways and can be used for different purposes. Most photodetectors fall into the phototube, thermal detector, or camera category. These photodetectors are used for communication, navigation, and record keeping. Types of Photodetectors Phototube …
Reed-Solomon is an algorithm for Forward Error Correction (FEC). Reed-Solomon was introduced by Irving S. Reed and Gustave Solomon of MIT Labs in Polynomial Codes Over Certain Finite Fields, which was published in the Journal of the Society for Industrial and Applied Mathematics in 1960. Reed-Solomon does not specify a block size or a specific …
A spark gap consists of two electrodes separated by a small gap that is filled by a gas, usually air. The potential difference across the gap increases until it reaches the level where the gas ionizes and current flows across it for a brief time. The two types of spark gap are the static and …
A frequency changer makes it possible to change electricity moving at one frequency to another frequency. However, in order to fully understand what a frequency changer does, it is helpful to understand the frequency of electricity. The Frequency of Electricity Electricity doesn't move at one specific speed. In fact, it can move at many speeds. …
Quadrature Amplitude Modulation (QAM) is a complicated name for a simple technique. In the simplest of terms, Quadrature amplitude modulation is the combination of amplitude modulation and phase shift keying. More technically, quadrature amplitude modulation is a system of modulation in which data is transferred by modulating the amplitude of two separate carrier waves, mostly …
A battery isolator is used to prevent primary battery systems from being drained and are mostly used in car stereo systems. These devices cause a secondary/auxiliary battery to be drained instead of the vehicle’s primary battery. This is so whether the stereo is used when the engine is turned off or if an after-market stereo …
A spark-gap transmitter is a mechanism for producing radio signals. It has been the primary radio transmission device during the early years of radio technology. It was soon superseded by other transmitters due to its discontinuous radio wave production and widely varying frequencies. How a Spark-Grap Transmitter Works A spark gap transmitter is basically composed …
A TRIAC is used in AC power control applications in order to switch high voltages over both parts of the AC waveform. As a result, TRIAC circuits are used in a number of applications that require power switching. The TRIAC was developed after the thyristor, which controls AC current over one half of the cycle. …
A multimeter combines several electrical meters into one hand-held unit. Basic multimeter models measure voltage, current, and resistance. Advanced models also measure temperature, inductance, capacitance, duty cycle, and frequency. They can also test diodes and transistors. Some even work as an oscilloscope. The two main types of multimeters are digital and analogue. Parts of a …