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 …
LCD projectors work by using three liquid crystal panels, a lamp, a prism, and filters to create the image on the screen. The lamp provides white light that passes through a polarizing filter. Polarizing works by accepting light that is traveling on the same plane. All other light will be blocked. From the polarizing filter …
L band is a fequency range between 390MHz and 1.55GHz which is used for satellite communications and for terrestrial communications between satellite equipment. The high frequencies utilized by C band, Ku band, and Ka band would suffer from high signal loss when transported over a copper coax cable such as an Intra-Facility Link. An LNB …
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 …
ODU (Out-Door Unit) refers to the set of satellite equipment which is placed outside of the building. The ODU typically includes a satellite dish, a feedhorn, and a LNB (Low Noise Block). In bi-directional satellite systems, the ODU will also include a BUC (Block Up Convertor). The ODU is connected to the IDU (In-Door-Unit) by …
A relay is a remote switch controlled by current, magnetism, or temperature. The relay was invented in 1835 by Joseph Henry (1979-1878), an American scientist. Relays are a common component in many devices, and there are many different types of relays. Relay Types The two main types of relay are electromechanical and solid-state. Electromechanical relays …
A transponder is an automatic electronic monitoring or control device that receives, cross-examines, amplifies and retransmits the arriving signal. It is primarily implemented in wireless communication. The word ‘Transponder’ itself is a combination of two words; transmitter and responder (occasionally abbreviated to TPDR, TR, XPNDR, and XPDR). A transponder works by receiving a signal on …
Resistors can come in different sizes and shapes allowing for different voltages to go through it. However, unless the size of the resistor is large, the code is rarely written on it because it would require very tiny markings. Therefore, a system was developed to use colors to determine the resistor code. In other words, …
Intersymbol interference is a signal distortion in telecommunication. One or more symbols can interfere with other symbols causing noise or a less reliable signal. The main causes of intersymbol interference are multipath propagation or non-linear frequency in channels. This has the effect of a blur or mixture of symbols, which can reduce signal clarity. If …
The siemens is the standard unit of electrical conductance. It is the inverse of resistance and is equal to one divided by resistance, or current divided by voltage. One siemens is equal to one ampere per volt. History of the Siemens The siemens was defined at an international conference in 1881, and is named after …