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Radio-frequency Sweep
Radio frequency sweep or frequency sweep or RF sweep apply to scanning a radio frequency band for detecting signals being transmitted there. This is implemented using a radio receiver having a tunable receiving frequency. As the frequency of the receiver is changed to scan (sweep) a desired frequency band, a display indicates the power of the signals received at each frequency. Methods and tools A spectrum analyzer is a standard instrument used for RF sweep. It includes an electronically tunable receiver and a display. The display presents measured power (y axis) vs frequency (x axis). The power spectrum display is a two-dimensional display of measured power vs. frequency. The power may be either in linear units, or logarithmic units (dBm). Usually the logarithmic display is more useful, because it presents a larger dynamic range with better detail at each value. An RF sweep relates to a receiver which changes its frequency of operation continuously from a minimum frequency to a m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectrum Analyzer
A spectrum analyzer measures the magnitude of an input signal versus frequency within the full frequency range of the instrument. The primary use is to measure the power of the spectrum of known and unknown signals. The input signal that most common spectrum analyzers measure is electrical; however, spectral compositions of other signals, such as acoustic pressure waves and optical light waves, can be considered through the use of an appropriate transducer. Spectrum analyzers for other types of signals also exist, such as optical spectrum analyzers which use direct optical techniques such as a monochromator to make measurements. By analyzing the spectra of electrical signals, dominant frequency, power, distortion, harmonics, bandwidth, and other spectral components of a signal can be observed that are not easily detectable in time domain waveforms. These parameters are useful in the characterization of electronic devices, such as wireless transmitters. The display of a spectru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Super Bowl
The Super Bowl is the annual final playoff game of the National Football League (NFL) to determine the league champion. It has served as the final game of every NFL season since 1966, replacing the NFL Championship Game. Since 2022, the game is played on the second Sunday in February. Prior Super Bowls were played on Sundays in early to mid-January from 1967 to 1978, late January from 1979 to 2003, and the first Sunday of February from 2004 to 2021. Winning teams are awarded the Vince Lombardi Trophy, named for the coach who won the first two Super Bowls. Due to the NFL restricting use of its "Super Bowl" trademark, it is frequently referred to as the "big game" or other generic terms by non-sponsoring corporations. The day the game is played is often referred to as "Super Bowl Sunday" or simply "Super Sunday". The game was created as part of a 1966 merger agreement between the NFL and the competing American Football League (AFL) to have their best teams compete for a champi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Technology
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates the waves, and received by another antenna connected to a radio receiver. Radio is very widely used in modern technology, in radio communication, radar, radio navigation, remote control, remote sensing, and other applications. In radio communication, used in radio and television broadcasting, cell phones, two-way radios, wireless networking, and satellite communication, among numerous other uses, radio waves are used to carry information across space from a transmitter to a receiver, by modulating the radio signal (impressing an information signal on the radio wave by varying some aspect of the wave) in the transmitter. In radar, used to locate and track objects like aircraft, ships, spacecraft ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Measuring Instruments
A measuring instrument is a device to measure a physical quantity. In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events. Established standard objects and events are used as units, and the process of measurement gives a number relating the item under study and the referenced unit of measurement. Measuring instruments, and formal test methods which define the instrument's use, are the means by which these relations of numbers are obtained. All measuring instruments are subject to varying degrees of instrument error and measurement uncertainty. These instruments may range from simple objects such as rulers and stopwatches to electron microscopes and particle accelerators. Virtual instrumentation is widely used in the development of modern measuring instruments. Time In the past, a common time measuring instrument was the sundial. Today, the usual measuring instru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laboratory Equipment
A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: physicians' offices, clinics, hospitals, and regional and national referral centers. Overview The organisation and contents of laboratories are determined by the differing requirements of the specialists working within. A physics laboratory might contain a particle accelerator or vacuum chamber, while a metallurgy laboratory could have apparatus for casting or refining metals or for testing their strength. A chemist or biologist might use a wet laboratory, while a psychologist's laboratory might be a room with one-way mirrors and hidden cameras in which to observe behavior. In some laboratories, such as those commonly used by computer scientists, computers (sometimes supercomputers) are used for either simulations or the analysis of data. Scien ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronic Test Equipment
Electronic test equipment is used to create signals and capture responses from electronic devices under test (DUTs). In this way, the proper operation of the DUT can be proven or faults in the device can be traced. Use of electronic test equipment is essential to any serious work on electronics systems. Practical electronics engineering and assembly requires the use of many different kinds of electronic test equipment ranging from the very simple and inexpensive (such as a test light consisting of just a light bulb and a test lead) to extremely complex and sophisticated such as automatic test equipment (ATE). ATE often includes many of these instruments in real and simulated forms. Generally, more advanced test gear is necessary when developing circuits and systems than is needed when doing production testing or when troubleshooting existing production units in the field. Types of test equipment Basic equipment The following items are used for basic measurement of voltages, cu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Technical Surveillance Counter-measures
Countersurveillance refers to measures that are usually undertaken by the public to prevent surveillance, including covert surveillance. Countersurveillance may include electronic methods such as technical surveillance counter-measures, which is the process of detecting surveillance devices. It can also include covert listening devices, visual surveillance devices, and countersurveillance software to thwart unwanted cybercrime, such as accessing computing and mobile devices for various nefarious reasons (e.g. theft of financial, personal or corporate data). More often than not, countersurveillance will employ a set of actions (countermeasures) that, when followed, reduce the risk of surveillance. Countersurveillance is different from sousveillance (inverse surveillance), as the latter does not necessarily aim to prevent or reduce surveillance. Types Technical surveillance counter-measures Electronic countermeasures Most bugs emit some form of electromagnetic radiation, usually ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectrum Management
Spectrum management is the process of regulating the use of radio frequencies to promote efficient use and gain a net social benefit.Martin Cave, Chris Doyle, William Webb, ''Modern Spectrum Management'', Cambridge University Press, 2007 The term ''radio spectrum'' typically refers to the full frequency range from 1 Hz to 3000 GHz (3 THz) that may be used for wireless communication. Increasing demand for services such as mobile telephones and many others has required changes in the philosophy of spectrum management. Demand for wireless broadband has soared due to technological innovation, such as 3G and 4G mobile services, and the rapid expansion of wireless internet services. Since the 1930s, spectrum was assigned through administrative licensing. Limited by technology, signal interference was once considered as a major problem of spectrum use. Therefore, exclusive licensing was established to protect licensees' signals. This former practice of discrete bands license ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Measuring Receiver
In telecommunication, a measuring receiver or measurement receiver is a calibrated laboratory-grade radio receiver designed to measure the characteristics of radio signals. The parameters of such receivers (tuning frequency, receiving bandwidth, gain) can usually be adjusted over a much wider range of values than is the case with other radio receivers. Their circuitry is optimized for stability and to enable calibration and reproducible results. Some measurement receivers also have especially robust input circuits that can survive brief impulses of more than 1000 V, as they can occur during measurements of radio signals on power lines and other conductors. Applications Measuring receivers are used with calibrated antennas to * determine the signal-strength and standards-compliance of broadcast signals, * investigate and quantify radio-frequency interference, * determine compliance of a device with electromagnetic interference and TEMPEST standards and regulations. Measuring rec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wireless Intercom
A wireless intercom is a telecommunications device that enables voice communication without the need to run copper wires between intercom stations. A wired intercom system may incorporate wireless elements. There are many types of wireless intercom systems on the market. Most wireless intercom systems communicate by radio waves using one of the frequencies allotted by various government agencies. Some wireless intercom systems communicate using the 802.11 standard. There are also systems that advertise themselves as wireless, but communicate over existing building AC electrical wiring. Basic terms *Station - A wireless intercom unit. *Outdoor Intercom - This is an intercom that can be placed by a building's doors and it operates like a doorbell, but people inside can talk to the visitor. *Channels - Some wireless intercom systems have more than one channel so private conversations can occur between groups of intercoms. *Range - This is the maximum range an intercom will communica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency Hopping
Frequency-hopping spread spectrum (FHSS) is a method of transmitting radio signals by rapidly changing the carrier frequency among many distinct frequencies occupying a large spectral band. The changes are controlled by a code known to both transmitter and receiver. FHSS is used to avoid interference, to prevent eavesdropping, and to enable code-division multiple access (CDMA) communications. The available frequency band is divided into smaller sub-bands. Signals rapidly change ("hop") their carrier frequencies among the center frequencies of these sub-bands in a predetermined order. Interference at a specific frequency will affect the signal only during a short interval. FHSS offers four main advantages over a fixed-frequency transmission: # FHSS signals are highly resistant to narrowband interference because the signal hops to a different frequency band. # Signals are difficult to intercept if the frequency-hopping pattern is not known. # Jamming is also difficult if the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wireless Microphone
A wireless microphone, or cordless microphone, is a microphone without a physical cable connecting it directly to the sound recording or amplifying equipment with which it is associated. Also known as a radio microphone, it has a small, battery-powered radio transmitter in the microphone body, which transmits the audio signal from the microphone by radio waves to a nearby receiver unit, which recovers the audio. The other audio equipment is connected to the receiver unit by cable. In one type the transmitter is contained within the handheld microphone body. In another type the transmitter is contained within a separate unit called a "bodypack", usually clipped to the user's belt or concealed under their clothes. The bodypack is connected by wire to a "lavalier microphone" or "lav" (a small microphone clipped to the user's lapel), a headset or earset microphone, or another wired microphone. Most bodypack designs also support a wired instrument connection (e.g., to a guitar). Wir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
