A fitting that supplies a passage between two sets of equipment when they cannot be directly interconnected.

Adaptive array antenna is a type of advanced ’smart’ antenna technology that continually monitors a received signal and dynamically adapts signal patterns to optimize wireless system performance. The arrays use signal processing algorithms to adapt to user movement, to changes in the radio-frequency environment, and to multi-path and co-channel interference.

Analog-to-Digital Converter (ADC, A/D or A to D) is an electronic device that converts continuous signals to discrete digital numbers. The reverse operation is performed by a digital-to-analog converter (DAC). ADC can uniquely represent all analog input values within a specified total input range by a limited number of digital output codes. Refer also to DAC.

An Analog system uses an analog transmission method to send voice, video, and data, using analog signals (such as electricity or sound waves) that are continuously variable rather than discrete units as in digital transmissions. Mobile analog systems include AMPS, NMT and ETACS.

Analog Transmission refers to signals propagated through the medium as continuously varying electromagnetic waves.

Attenuation refers to the decreasing of signal magnitude between two points. These points may be along a radio path, transmission line, or other devices.

Attenuator is a device specifically designed to decrease the magnitude of a signal transmitted through it.

A Band Pass Filter is a radio wave filter with a specific range of frequencies in which it is designed to pass. It rejects frequencies outside the pass-band range. A resistor-inductor-capacitor circuit is an example of a Band Pass Filter.

Bandwidth usually identifies the capacity of a circuit or amount of data that can be sent through a given circuit. It may be user-specified in a PVC. It is an indication of the amount of data that is passing over a medium. Also, bandwidth is the portion of the frequency spectrum required to transmit desired information. Each radio channel has a center frequency and additional frequencies above and below this carrier frequency which is used to carry the transmitted information. The range of frequencies from the lowest to the highest used is called the bandwidth.

Bandwidth Ratio is the ratio of two devices having differing bandwidths, not necessarily in the same frequency spectrum.

Bit Error Rate or Bit Error Ratio (link quality specification/testing) (BER) is a measure of transmission quality. The ratio of error bits to the total number of bits transmitted. A bit error rate of 10-6 refers to an average of one error per million bits. It is generally shown as a negative exponent, (for example, 10-7 which means 1 out of 107 bits are in error or 1 out of 10,000,000 bits are in error). Bit Error Rate is the fraction of a sequence of message bits that are in error.

Bit Error Rate Test/Tester (BERT) is a test that gauges the quality of the T1 or digital line. By sending a known pattern to another device across the span, the far end device can compare incoming pattern to its own, thereby indicating bit errors on the line.

Complementary Cumulative Distribution Function (CCDF) is a method used to characterize the peak power statistics of a digitally modulated signal. The CCDF curve can be used to determine design parameters for CDMA systems (such as the amount of back-off to run in a power amplifier).

In wireless communication, a Cell is the geographic area encompassing the signal range from one base station (a site containing a radio transmitter/receiver and network communication equipment). Wireless transmission networks are composed of many hexagonal, overlapping cell sites to efficiently use radio spectrum for wireless transmissions. Also, cell is the basis for the term cellular phone.

Cell Delineation is the process for recognizing the beginning and end of ATM cells within the raw serial bit stream.

Cell Site, also called Base Station, is the local cellular tower and radio antenna (including the radios, controller, switch interconnect, etc.) that handles communication with subscribers in a particular area or cell. A cellular network is made up of many cell sites, all connected back to the switch via landline or microwave.

In wireless communications, cellular refers most basically to the structure of the wireless transmission networks which are comprised of cells or transmission sites. Cellular is also the name of the wireless telephone system originally developed by Bell Laboratories that used low-powered analog radio equipment to transmit within cells. The terms cellular phone or cell phone are used interchangeably to refer to wireless phones. Within the wireless industry, cellular is also used to refer to non-PCS products and services.

Coaxial Cable (Coax) is a type of electrical communications medium used in the LAN environment. This cable consists of an outer conductor concentric to an inner conductor, separated from each other by insulating material and covered by some protective outer material. This medium offers large bandwidth, supporting high data rates with high immunity to electrical interference and a low incidence of errors. Coax is subject to distance limitations and is relatively expensive and difficult to install.

Configuration Commands are commands that are issued to an instrument to change a specific instrument configuration parameter or parameters.

Cell site On Wheels (COW) is a mobile site placed at a location to fill in or increase coverage.

Cell Site on Light Truck (CPLT) is a mobile site on a vehicle placed at a location to fill in or increase coverage.

Continuous Phase Modulation (CPM) is a phase modulation technique employing smooth transitions between signal states. This reduces sidelobe spectral energy and improves co-channel performance.

Displayed Average Noise Level (DANL): Displayed average noise level is sometimes confused with the term Sensitivity. While related, these terms have different meanings. Sensitivity is a measure of the minimum signal level that yields a defined signal-to-noise ratio (SNR) or bit error rate (BER). It is a common metric of radio receiver performance. Spectrum analyzer specifications are always given in terms of the DANL. One of the primary uses of a spectrum analyzer is to search out and measure low-level signals. The limitation in these measurements is the noise generated within the spectrum analyzer itself. This noise, generated by the random electron motion in various circuit elements, is amplified by multiple gain stages in the analyzer and appears on the display as a noise signal. On a spectrum analyzer, this noise is commonly referred to as the Displayed Average Noise Level, or DANL 1. While there are techniques to measure signals slightly below the DANL, this noise power ultimately limits our ability to make measurements of low-level signals.

Decibel or deciBel (dB) is a unit for measuring relative power ratios in terms of gain or loss. The units of dB are expressed in terms of the logarithm to base 10 of a ratio and typically are expressed in watts. For example, a -3dB loss indicates a 50% loss in power; a +3dB reading is a doubling of power; 10 dB indicates an increase (or a loss) by a factor of 10; 20 dB indicates an increase (or a loss) of a factor of 100; 30 dB indicates an increase (or a loss) by a factor of 1000.

Decibels referenced to the carrier (dBc) is a technique for expressing a power measurement in logarithmic form using the carrier power as a reference. The units are used to describe how far down signals and noise are relative to a known signal. Typical use of this term is to describe spurious signals and noise compared to a desired transmit signal.

Decibels referenced to a dipole antenna (dBd) is a technique for expressing a power gain measurement in logarithmic form using a standard dipole antenna as a reference. dBd is a measurement of signal gain used in radio antenna design. Specifically, dBd refers to signal gain in a dipole radiator.

dBm is a decibel value referenced to a milliWatt (dBm). This is a technique for expressing a power measurement in logarithmic form using 1 mW as a reference. dBm is a decibel ratio (log 10) of Watts (W) to one milliwatt (1mW). dBm, therefore, represents absolute power.

Dynamic Host Configuration Protocol (DHCP)

Digital Signal Processing (DSP)

Dedicated Short Range Communications (DSRC): DSRC is a system that is intended for communications between two vehicles, or from one vehicle to a roadside network. Refer to IEEE 802.11p.

Distance-To-Fault (DTF) is the distance from the instrument output connector (or the end of a test lead) to a problem area, as indicated by a peak in the displayed signal.

Digital Video Broadcasting - Cable (DVB-C) is the DVB European consortium standard for the broadcast transmission of digital television over cable. This system transmits an MPEG-2 family digital audio/video stream, using a QAM modulation with channel coding.

Digital Video Broadcasting - Handheld (DVB-H) is a technical specification for bringing broadcast services to handheld receivers and was formally adopted as ETSI standard EN 302 304 in November, 2004. The major competitor of this technology is DMB (Digital Multimedia Broadcasting).

Digital Video Broadcasting-Satellite (DVB-S) is the original Digital Video Broadcasting (DVB) forward error coding and modulation standard for satellite television and dates from 1995. It is used via satellites serving every continent of the world. DVB-S is used in both MCPC and SCPC modes for broadcast network feeds, as well as for direct broadcast satellite services like Sky TV (UK) via Astra in Europe, Dish Network in the U.S., and Bell ExpressVu in Canada. The transport stream delivered by DVB-S is mandated as MPEG-2.

Digital Video Broadcasting - Terrestrial (DVB-T) is the DVB European consortium standard for the broadcast transmission of digital terrestrial television. This system transmits a compressed digital audio/video stream, using OFDM modulation with concatenated channel coding (COFDM). The adopted source coding methods are MPEG-2 and, more recently, H.264.

Fast Fourier Transform (FFT) is an efficient algorithm to compute the Discrete Fourier transform (DFT) and its inverse. FFTs are of great importance to a wide variety of applications, from digital signal processing to solving partial differential equations to algorithms for quickly multiplying large integers.

Frequency Modulation (FM) is a form of angle modulation in which the instantaneous frequency of a sine-wave carrier is caused to depart from the carrier frequency by an amount proportional to the instantaneous value of the modulating wave. In FM, signals of different frequencies represent different data values.

In FM modulated systems, the FM Modulation Index is the ratio of the peak frequency deviation to the maximum modulating frequency. The higher the index, the greater the received quality. FM Modulation Index = (peak frequency deviation / maximum modulation frequency)

FM Threshold is the point at which the input signal power is just strong enough to enable the receiver demodulator circuitry to successfully detect and recover a good quality television picture from the incoming video carrier.

GigaHertz (GHz) is one billion (1 x 10E9) hertz, which is a measurement of frequency.

The Global Positioning System (GPS) is a space-based global navigation satellite system (GNSS) that provides reliable location and time information in all weather and at all times when and where an unobstructed line of sight is available to four or more GPS satellites. The system is maintained by the United States government and is freely accessible by anyone with a GPS receiver. The Global Positioning System is making it possible for people using ground receivers to determine their geographic location within 10 to 100 meters. The satellites use simple mathematical calculations to broadcast information that is translated as longitude, latitude, and altitude by Earth-based receivers.

Intermediate Frequency (IF) is a frequency to which a carrier frequency is shifted as an intermediate step in transmission or reception. An intermediate electromagnetic frequency is generated by a superheterodyne radio receiver.

An Internet Protocol address (IP address) is usually a numerical label that is assigned to each device (computer or printer, for example) that is participating in a computer network that uses the Internet Protocol for communication. An IP address serves two main functions: location addressing and host (or network) interface identification. The Internet Protocol originally defined an IP address as a 32-bit number. This was known as Internet Protocol Version 4 (IPv4), which is still in use. Growth of the Internet requires a new addressing system. An Internet Protocol Version 6 (IPv6) that uses 128 bits for the address was developed in 1995, and it is standardized as RFC 2460. IPv6 began being deployed worldwide in the year 2000. IP addresses are binary numbers, but they are usually stored in text files and displayed in human-readable notations, such as decimal nnn.nnn.nnn.nnn or 172.16.255.1 (for IPv4), and hexadecimal nnnn.nnnn.nnnn.nnnn.nnnn.nnnn.nnnn.nnnn or 2C01:AB18:0:1234:FF03:567C:8:1 (for IPv6). In IPv4, each decimal group (nnn) represents values from 000 to 255, or binary values of 8 bits. In IPv6, each hexadecimal group (nnnn) represents values from 0000 to FFFF, or binary values of 16 bits (0000 0000 0000 0000 to 1111 1111 1111 1111).

Linear Power Amplifier (LPA) is the final amplification stage in a multicarrier transmitter that has been designed and optimized to produce a linear response. By operating in the linear mode, the amplifier reduces the non-linear effects that produce intermodulation products and side-lobe spectra that cause adjacent channel interference.

Line Reflect Line (LRL, also called TRL) method of calibration developed by Anritsu. LRL uses two (or more) transmission lines and a reflect standard (for each port). The line lengths are important because the two lines look electrically distinct at all times (meaning it will not work at DC, nor at a frequency where the difference in length is an integral number of half wavelengths). The reflect standard is not too important because it is only assumed to be symmetric (the same at both ports) and not too high a return loss (practically speaking, even 20 dB return loss will usually work). The lines are assumed to be perfect, with no mismatch, which usually means airlines for coaxial calibrations, although other structures can be used. On-wafer transmission lines can usually be very good, and this cal approach will work well if one can handle the required probe movement.

Line Reflect Match (LRM) method of calibration developed by Anritsu. In LRM, one of the lines of the LRL method is replaced with a match (or load). For basic LRM, the match is assumed to be perfect, and thus represents a line of infinite length. For cases where the load is well understood, improvement in accuracy can be achieved by using ALRM and incorporating the load model. So in some sense, this cal relates back to the concept of the defined standards. Because only one line is involved, this calibration can work down to DC and up to very high frequencies (practically limited by the match knowledge/characterization). Some variations allow one to trade one of the match measurements for a pair of additional reflect measurements (a second reflect standard is needed). Because of the requirement (in this case) that the reflect standards be distinct, the calibration may become band limited.

Megahertz (MHz) - One MHz is equal to one million Hertz, and is a measurement of frequency.

Noise Figure (NF) is a measure of degradation of the signal-to-noise ratio (SNR) that is caused by components in a radio frequency (RF) device. The noise factor (F) of a system is defined as the signal-to-noise ratio of the input power of the system divided by the signal-to-noise ratio of the output power of that system. NF (the noise figure) is defined as the decibel value of the noise factor. NF = 10log (F) where log uses the base 10, or common log. This formula is valid only when the input termination is at standard noise temperature.

Occupied Bandwidth (OBW) is a measure of the bandwidth containing 99% of the total integrated power of the transmitted spectrum, centered on the assigned channel frequency. Interference to other channels or to other systems can occur if OBW is too large.

Over-The-Air (OTA) refers generally to any transfer of information or signal that takes place in a wireless environment, rather than using a wired connection. OTA is usually used in connection with a standard defining the provisioning of mobile devices and applications, such as downloading or uploading content or software, and commonly used in conjunction with the Short Messaging Service (SMS). SMS OTA Messages contain information that is used to configure the settings of a WAP browser in a mobile phone (refer to SMS and WAP).

Resolution Bandwidth (RBW) With spectrum analyzers, a narrow band filter is swept across a frequency span to create the spectrum display. The filter bandwidth (RBW) determines the frequency resolution across the frequency axis.

Remote Access Point, also known as relay access point, is one of a number of secondary access points in a wireless network that uses Wireless Distribution System (WDS) to extend its range. Remote access points connect to a master access point.

Power loss in a transmission cable due to mismatch reflection, cable loss, etc.

Radio Frequency (RF) generally refers to wireless communications with frequencies below 300 GHz. Formally, according to the Article 2 of the Radio Law, radio frequency is below 3,000 GHz. Radio frequencies can be used for communications between a mobile telephone and an antenna mast.

Received Signal Strength Indicator (RSSI) is a measurement of the power present in a radio signal when received and measured. RSSI is useful for observing signal strength at a single frequency over time.

Signal loss is the amount of signal strength that’s lost in antenna cable, connectors, and free space. Signal loss is measured in decibels.

A Smith Chart is a graphical aid for electrical and electronics characteristics in radio frequency (RF) circuits. Smith Chart was invented by Phillip Smith at Bell Laboratories in 1939. The chart can be used to display multiple parameters, such as impedance, and admittance.

Short-Open-Line-Reciprocal (SOLR), Short-Short-Line-Reciprocal SSLR), and Short-Short-Short-Reciprocal (SSSR) are calibrations similar to SOLT/SSLT/SSST, but used when a good Thru is not available. They have some accuracy degradation due to a less defined Thru and have disadvantages of the parent calibration.

Short-Open-Line_Thru (SOLT) is a calibration (common coaxially) with simple and redundant standards. It is not band-limited. It requires well-defined standards. It has lower accuracy at higher frequencies, and is poor with on-wafer.

A Tower Mounted Amplifier (TMA) amplifies signals from an antenna to reduce the noise figure of a base transceiver station (BTS). This helps to improve the overall sensitivity of the BTS. A TMA is a low-noise amplifier (LNA) that is usually mounted as close as practical to the antenna in Base Transceiver Stations or in mobile masts. When using a TMA, the antenna is able to receive weaker signals.

Video Bandwidth (VBW)

Voltage Standing Wave Ratio (VSWR)