Backward Error Correction, also known as an “Automatic Repeat Request” is an error correction technique in which a receiving device sends a request to the source device to re-send information. Backward Error Correction is used in situations where some of the transmitted data has been lost or corrupted during transit and the transmitting device must …
A balun is an electrical transformer that is used to convert electrical signals to and from balanced and unbalanced signals. They are normally used to connect lines that have different levels of impedance and are commonly used in the home for connecting HD and traditional antennas. Baluns are also used throughout industry, although it is …
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 It was soon superseded by other transmitters due to its discontinuous radio wave production and widely varying frequencies.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 …
An attic antenna is one that is mounted inside of an attic in order to provide maximum range as well as protection from rain, snow, sun, wind, and animals. Attic antennas are rather common and provide quality reception for those who live in rural areas, away from most radio transmitters. While attic antennas do not …
XM radio is one of the two primary satellite radio services in North America. The service is operated by Sirius XM Radio and publishes premium radio content in addition to more than 70 music channels, 39 news, ports, talk, and entertainment choices, 23 play-by-play sports channels, and 21 regional and weather channels. XM radio channels …
Trickle charging, also called float charging, is the replacement of charge lost through self-discharge. Trickle chargers work at a lower rate than quick chargers, and are used to keep a battery at full charge, not to charge it from empty. Some battery chargers use electronics to control both quick and trickle charge modes, allowing them …
An ultrasonic sensor is a device that works in much the same way as RADAR and SONAR. In fact, ultrasonic sensors mimic bats and other animals’ natural ability to use ultrasonic frequencies for navigation. Ultrasonic sensors broadcast a powerful, ultrasonic frequency, then detect the ultrasonic sound waves as they bounce off of objects and return …
A fractal antenna is a diamond-shaped antenna that maximizes the total amount of material within a given amount of space that transmits or receives electromagnetic waves. Fractal antennas do this by making each section of the antenna its own separate dipole. Because of this design, fractal antennas operate at many different frequencies and wavebands, allowing …
Pulse position modulation is a signal modulation technique that allows computers to share data by measuring the time each data packet takes to reach the computer. It is often used in optical communication, such as fiber optics, in which there is little multi-pathway interference. Pulse position modulation exclusively transfers digital signals and cannot be used …
A metal detector uses an electromagnetic field to detect the presence of a concealed metal object. The range depends on the strength of the field, and is usually less than one meter from the search head. The three detection methods are beat frequency oscillation, very low frequency, and pulse induction. Metal detectors were first introduced …