A

"A" Carrier

The non-wire cellular company, that operates in radio frequencies from 824 to 849 MHz. 

Acquisition Time

Amount of time required for a GPS unit to lock onto 3 satellites to provide a "2D View" of present position.

Adapter/Adaptora

A waveguide or coaxial device used to mate two dissimilar transmission lines or connectors.

ADC 

Analog-to-Digital Converter. 

AGC

Automatic Gain Control - A feedback control circuit which maintains the gain or output power level of an amplifier constant over a wide range of input signal levels. 

Airtime

Time spent on a cellular or Digital PCS phone, billed to the subscriber on a per second or per minute basis. 

Alumina (Aluminum Oxide, Al2O3)

Alumina-ceramic is used as the substrate material on which is a deposited thin conductive and resistive layer for thin film microwave integrated circuits. 

AM

Amplitude modulation; a method of broadcasting in which the desired audio or video signal modulates the amplitude of a 'carrier' signal.

Analog

Information that is reproduced using a continuously varying electronic signal. 

Analog-to-Digital Converter 

A device that converts an analog input voltage to a digital output word. These are also known as ADCs, and have varying degrees of input range and output resolution. 

Antenna

An array of metal rods or wires used to intercept radio waves and convert them into electrical currents. In microwave applications, often a parabolic reflector with associated feed mechanism.

AM Noise

The random and/or systematic variations in output power amplitude. Usually expressed in terms of dBc in a specified video bandwidth at a specified frequency removed from the carrier. 

AM-PM Conversion

AM-PM conversion represents a shift in the phase delay of a signal when a transistor changes from small-signal to large-signal operating conditions. This parameter is specified for communications amplifiers, since AM-PM conversion results in distortion of a signal waveform.

AMPS

Advanced Mobile Phone Service, the standard for analog cellular telephones.

ANA

Automatic Network Analyzer - A computer-controlled test system that measures microwave devices in terms of their small signal S-parameters. The use of this instrument by both engineering and production permits quick and accurate characterization of the input and output impedance, gain, reverse isolation of individual units and the degree of match between units.

Analog

The traditional method of transmitting voice signals where the radio wave is based on electrical impulses, which occur when speaking into the phone.

Analog Driver

An accessory circuit for an oscillator of filter that permits its frequency to be changed by a continuously varying signal.

Aspect Ratio

The proportions of a TV or film picture, generally given as the ratio of the width to height. The standard TV picture has an aspect ratio of 4x3, or 4:3. High-definition video systems may have aspect ratios of 6x8 or greater.

ATE

Automatic (or Automated) Test Equipment

ATP

Acceptance Test Procedure

Attenuator

A device or network that absorbs part of a signal and transmits the remainder with a minimum of distortion. 

B

"B" carrier

The wireline cellular carrier, usually the local telephone company that operates on the frequencies 869 to 894 MHz. 

Back metallization

Metal applied to the side of the transistor wafer opposite the active areas. Provides the collector contact in bipolar transistors and permits the transistor chips to be bonded to the package or thin-film circuit substrate. 

Balanced Amplifier

A transistor amplifier stage in which two identical transistors are used and the input signal and output power is equally divided between them. This technique produces approximately twice the output power of a single transistor stage with generally improved dynamic range and reduced VSWR. 

Balanced Module

A gain module of an amplifier that utilizes a 3 dB input splitter and a 3 dB output coupler to combine the power of two or more paralleled FET’s. Balanced modules have the characteristics of good input and output VSWR, and the benefit of indirect stability under adverse source and load conditions. 

Ball Bond (MIC)

A bond formed when a ball-shaped end interconnecting wire is deformed by thermo-compression against a metallized pad. The bond is also designated a nail head bond from the appearance of the flattened ball. 

Base Station

The fixed transmitter/receiver with which a mobile radio transceiver establishes a communication link to gain access to the public-switched telephone network. 

Bearing (BRG)

The precise compass direction (in degrees) from your present position to the next waypoint. (Readings are selectable in either degrees magnetic or true north).

Beryllium Oxide (BeO)

A ceramic material having very high heat conductivity, good thermal shock resistance and high strength. Used in metal/ceramic packages for higher power microwave transistors and as substrates in some MIC power amplifiers. 

BIT/BITE

Built-in Test/Built-in Test Equipment - Some products have provisions for connection to customer-supplied test or test equipment that is a part of the system in which the products are used. Generally, a military/aerospace term for equipment that contains an automatic self-testing function. 

BPSK

Bi Phase Shift Keying - A method of modulating a microwave carrier so that data is translated into 90° phase shifts of the carrier. 

Bonding Pad (MIC)

A metallized area at the end of a thin metallic strip to which a connection is to be made. 

Bonding Wire (MIC)

Fine gold or aluminum wire for making electrical connections in hybrid circuits. 

C

CAD/CAM

Computer Aided Design/ Computer Aided Manufacturing 

Cascadable

A device is cascadable if the output port of one such device can be connected to the input port of another such device without additional impedance matching being required. 

Cascade

A series of microwave amplifier stages connected in sequence (sometimes including limiters, attenuators or other elements) to produce the desired gain, power output and other performance characteristics. 

Cavity

A metallic enclosure which can be made to resonate at a desired frequency. Primarily used to describe a cavity filter, which is a highly-selective tuning element at microwave frequencies that may be used as the frequency-determining element of an oscillator, or as a lowpass, bandpass or highpass filter. Generally of fixed frequency or mechanically tunable over a very limited frequency range. 

C-band

The portion of the microwave spectrum (4,000-8,000 MHz) used most widely for distribution of video programs by satellite to cable systems. 

CCIS7 

Common Channel Interoffice Signaling System #7, a CCITT standard 

CCITT 

Consultative Committee for International Telephony and Telegraphy 

CDPD 

Cellular Digital Packet Data

Cell

The geographic area served by a single low-power transmitter/receiver. A cellular system's service area is divided into multiple "cells".

Ceramic

See: Beryllium Oxide, Alumina 

Certificate of Compliance

A document shipped with a customer-ordered product when required by contract that indicates that the product meets or exceeds all customer-specified performance characteristics. 

Channel

The width of the spectrum band taken up by a radio signal, usually measured in kilohertz (kHz). Most analog cellular phones use 30-kHz channels. 

Chip

The uncased and normally leadless form of an electronic component part, either passive or active, discrete or integrated. 

Circuit

The interconnection of the number of electrical elements and/or devices, performing desired electrical function. 

Circulator

A passive microwave device consisting of 3-ports that allows the signal entering each port to pass to the port adjacent to it (either clockwise or counter-clockwise) but not to the port in the other direction.

CNR 

Carrier-to-Noise Ratio 

Coaxial Cable

A cable consisting of one center conductor to carry a signal, surrounded concentrically (coaxial) by an insulating dielectric and a separate outer conductor (braid or metal jacket) which acts as a shield. 

Code-Division Multiple-Access (CDMA)

A digital technology that uses a low-power signal "spread" across a wide band-width. A call is assigned a code instead of a certain frequency. Using the identifying code and a low power signal, a large number of callers can use the same group of channels.

Cold Start

The process of powering up a new GPS receiver for the first time and having it search out and lock onto the satellites by itself, without the benefit of initialization data. This procedure is slower and may require up to 15 minutes for initial satellite acquisition only.

Combined Ripple and Spurious

The worst case transmission loss (in dB) within the YIG filter 3 dB passband due to the presence of passband spurious and or passband ripple responses. 

COMSAT

Communication Satellite Corporation, providing satellite communication services and chartered by the federal government. 

Control Devices

A component used to switch, limit, modulate or attenuate microwave signals. 

Conversion Compression Point (1 dB)

The specification which states the RF input power (in dBm) at which the IF output power will increase only 9 dB for a 10 dB increase in RF input power at stated LO power level. This specification provides an indication of the mixer two-tone intermodulation performance and usually is of most concern in high level mixing applications. 

Conversion Loss

The ratio (in dB) of the IF output power of a mixer to the RF input power. All conversion loss measurements and specifications are normally based on the mixer being installed in a system with wideband 50 ohm resistive terminations on all ports and a stated LO signal power level being applied. 

Coupler

A Waveguide device used to sample the microwave transmissions by means of coupling (combining) signals asymmetrically.  May be of the crossguide or directional variety.  Available at various coupling levels (typically 10 to 50 dB below the signal of interest).

Course Over Ground (COG)

The current direction (in degrees) that a GPS user is actually traveling, selectable in degrees magnetic or true north.

Crossguide Coupler

Or Cross Guide Coupler.  See "Coupler"

Cross Modulation Distortion

The amount of modulation impressed on an unmodulated carrier when a signal is simultaneously applied to the RF port of a mixer under specified operating conditions. The tendency of a mixer to produce cross modulation is decreased with an increase in conversion compression point and intercept point. 

Cross Track Error (XTE)

Digital reading on GPS steering screens that indicates precisely how far off the user is, to the right or left of the center of the course.

CT-1

Cordless telephone-first generation; any variety of North American, European, and Japanese analog cordless telephone. 

CT-2

Cordless telephone-second generation; a digital cordless telephone standard generally used in residential cordless phone, a telepoint application, or a small-office WPBX system. 

CT-3 

Cordless Telephone 3rd Generation (standards still formative) 

CTIA 

Cellular Telecommunications Industry Association 

CW

Continuous Wave - Signal of constant amplitude. Used to differentiate between the performance of a microwave component for continuous power levels vs. pulsed signals. For example, "This amplifier will accept up to +30 dBm CW (or continuous) or up to +50 dBm peak (up to 5 microsecond duration with low duty cycle) input power without performance degradation."  Also used to describe an unmodulated carrier.

D

DAC

Digital-to-Analog Converter. 

dB

Decibel - A logarithmic expression of ratios. Can be found by taking ten times the common logarithm of the ratio of two power levels, or 20 times the common logarithm of the ratio of two voltage levels. 

dBc

Decibel related to the signal carrier level 

dBm

Decibels related to 1mW - the standard unit of power level used in microwave work. For example, 0dBm= 1mW, +10 dBm = 10mW, +20dBm=100 mW, etc. 

dBi

Decibels related to isotropic. Relates the gain of an antenna relative to an isotropic (perfectly spherical pattern) antenna.

DBS

Direct Broadcast Satellite; a system that sends TV broadcasts directly from a communications satellite to home antennas, or dishes. 

DCC 

Digital Cross Connect. 

Decibel

See "dB"

Digital Cross Connect 

This is basically a passive box containing a bunch of chokes that provides patching and recabling capability. Its primary reason for existence is that it keeps radio frequency signals from feeding into digital circuitry. 

Digital-to-Analog Converter 

A device that converts a digital input word to an analog voltage output. These are also known as DACs, and have varying degrees of input resolution and range. 

Directional Coupler

See "Coupler"

DCS 1800

Digital communication service at 1800 MHz. An extension of the Global System for Mobile communications (GSM). 

DCT 

Dynamic Digital Cordless Telephone 

DDS 

Digital Data System 

DECT 

Digital European Cordless Telephony (standard) 

Desensitization

The compression in the IF output power from a desired RF input signal caused by a second high level signal being simultaneously applied to the RF port of a mixer. As a rule of thumb, in low level mixers, a desired RF input 3 dB below the mixer conversion compression point will begin to cause desensitization. 

Die

An uncased discrete or integrated device obtained from a semiconductor wafer. 

Die Attach

Attachment of a die or chip to the hybrid substrate. 

Dielectric Resonator

A high Q, temperature stable ceramic microwave resonator that is used in microwave oscillator circuits. It can exist in any regular geometrical form of resonates in various modes at frequencies determined by its dimensions and shielding conditions. 

Dielectric Resonator Material

Low loss, high permittivity (Er = 30 to 40) temperature stable ceramic material. Some of the commonly used materials are barium titanate, titanium niobiate, etc. The composition of these materials can be controlled to achieve any frequency variation with temperature between +10 and -10ppm. 

Differential GPS (DGPS)

A system devised initially by the U.S. Coast Guard to improve GPS accuracy levels to within 5 meters. It employs a land-based, fixed position, DGPS reference receiver to first calculate the Selective Availability errors, and then transmit the necessary correction factors to mobile GPS receivers in the area. DGPS systems require an added beacon receiver to communicate with the standard GPS unit.

Diffusion

The phenomenon of movement of matter at the atomic level from regions of high concentration to regions of low concentration. 

Digital Driver

An accessory circuit for an oscillator or filter which permits its frequency to be varied by varying a digital "word." A digital driver is also an accessory circuit interfacing a switch or attenuator to a digital command circuit. 

Digital European Cordless Telecommunications

A digital cordless telecommunications system intended initially for WPBX applications, later to be used in the home market. DECT supports both voice and data communications. 

Digital Modulation

A method of transmitting an analog (continuously variable) signal using the computer's binary code, 0s and 1s. Digital transmission offers a cleaner signal than analog technology. Cellular systems providing digital transmission are currently in operation in several locations.

Dish

The parabolic antenna used for transmitting and receiving signals from communication satellites. 

Distortion

Changes in a signal that involve the addition of spurious tones at frequencies not present in the original signal. In harmonic 'distortion' the spurious tones are at integral multiples of the original frequency. In 'intermodulation' distortion, discordant tones appear at the sums and differences of two original frequencies. 

Distance To Go (DTG)

Digital readout (selectable in miles, nautical miles or kilometers) displayed only when navigating to a waypoint. It simply indicates the remaining distance from present position to the next waypoint.

DOMSAT

Domestic communication satellite (as opposed to one confined to military uses). 

Downconverter

Integrated assembly of components required to convert microwave signals to an intermediate frequency range for further processing. Generally consists of an input filter, local oscillator filter, IF filter, mixer and frequently an LO frequency multiplier, plus one or more stages of IF amplification. May also incorporate the local oscillator, AGC/gain compensation components and RF preamplifier. 

Downlink

The satellite-to-earth microwave channel and related components such as the earth station receiving equipment. The satellite contains a downlink transmitter. Downlink components in the earth station are involved with the reception and processing of satellite-transmitted signals. 

Drive Level

The power level of the local oscillator signal applied to the LO port of a mixer. Operating a mixer with the maximum recommended LO drive level will result in the best two tone performance, lowest conversion loss and flattest conversion loss vs. frequency characteristics, reduced mixer-generated intermodulation products and will minimize 1/f noise in the output signal. A higher-than recommended LO power level will result in an increased noise figure and higher LO feed-through at both the RF and IF ports of the mixer. 

Dry Nitrogen Filled

A special process in which a unit is sealed and filled with dry nitrogen to help prevent fogging and internal corrosion.

DSP 

Digital Signal Processing (or Processors) 

DSS 

Digital Sequence Spread Spectrum 

Dual-Mode Phone

A phone that operates on both analog and digital networks. 

dV/dT

Device voltage temperature coefficient. 

Dynamic Range

The range from the minimum, which is at a level at or below the amplifiers' internally-generated noise, to a maximum input signal level that a component can accept and amplify without distortion. In regard to mixers, the range of RF input power levels over which a mixer can operate within a specified range of performance. The upper limit of the mixer dynamic range is controlled by the conversion compression point (also a function of LO drive), and the lower limit is set by the mixer noise figure. 

E

EAMPS 

Expanded Advanced Mobile Phone Service 

Earth station

The ground station that receives (downlink) and sends (uplink) signals to and from communication satellites. 

ECCM (Military)

Electronic Counter-Countermeasures - Equipment and techniques to allow electronic systems such as radar and communications to operate effectively while attempts are being made to disrupt or jam their operation.

ECM (Military)

Electronic Countermeasures - Equipment and techniques to reduce the effectiveness of opposing electronic systems such as radar and communications. Includes techniques such as chaff and barrage jamming as well as sophisticated methods to deceive the systems without indication to the opposing operators that their systems are being affected.

EDI

Electronic Data Interchange

Electronic Tuning

The maximum output frequency deviation that can be achieved without significantly affecting oscillator performance characteristics. This is achieved by adjusting the varactor diode coupled to the dielectric resonator. Typical DSO electronic tuning ranges are +0.1 of the center frequency.

ELINT (Military)

Electronic Intelligence - The intelligence information product of activities engaged in the collection and processing, for subsequent intelligence purposes of foreign, non-communications (radar, for example) electromagnetic radiation. Does not include communications intelligence (COMINT) or radiation from radioactive sources such as nuclear detonation.

ESM (Military)

Electronic Support Measures - Electronic warfare activities involving the search for, and interception, location, recording and analysis of, radiated electromagnetic energy for the purposes of exploitation in the support of military operations (includes ELINT, SIGINT).

EMI

Electromagnetic Interference - Unintentional interfering signals generated within or external to electronic equipment. Typical sources could be power-line transients, noise from switching-type power supplies and/or spurious radiation from oscillators. EMI is suppressed with power-line filtering, shielding, etc.

ENG

Electronic news gathering; the use of video cameras and tape recorders in place of film systems for news coverage by TV stations.

E-TDMA

Enhanced TDMA Access

ETSI

European Telecommunications Standards Institute. One of the European organizations responsible for establishing common industry wide standards for telecommunications.

Eutectic

The specific proportions of the constituents of an alloy having the lowest melting point. The system goes from totally molten to totally solid without going through a slushy range at the eutectic composition. 

EW (Military)

Electronic Warfare - Electronic warfare is military action involving the use of electromagnetic spectrum and actions to retain friendly use of the electromagnetic spectrum. 

F

FCC

Federal Communications Commission. The U.S. government agency responsible for allocation of radio spectrum for communication services. 

FDMA

Frequency Division Multiple Access

Ferrite

The term "ferrite" refers to various iron-containing compounds. Most commonly, in the field of electronics, the term refers to cores of various shapes, which are made of these materials. One of the properties of inductors that have ferrite cores is that their inductance varies with the current through them.

Ferrite Tuner 

A ferrite tuner is a ferrite core inductor that can be used to tune a resonant circuit.

FET

Field Effect Transistor - See GaAs FET. 

Feedback Amplifier

Microwave amplifiers (GaAs FET or bipolar transistor) using negative feedback in the amplification stages. Used to control input and output impedance, increase operating bandwidth and help minimize performance variations caused by inherent variations in transistor parameters. 

FHSS 

Frequency Hopping Spread Spectrum 

Field

A set of scanning lines that, when interlaced with another set, makes up the 'frame,' or complete TV picture. 

Fillet

A concave junction formed where two surfaces meet. 

Flatpack

In general microwave usage, a miniature hermetic package for MIC components, designed for a minimum height, with pins for RF and DC connections existing through the sides (narrowest dimensions), and designed to be surface mounted or "dropped in" to a cutout in a micro-strip printed circuit board. The leads and the largest surface of the package are in parallel planes. 

FLOPS 

Floating-Point Operations Per Second 

FM

Frequency modulation

Fmax

Maximum Frequency of Oscillation - The frequency at which unilateral gain equals unity. 

FM Noise/Phase Noise

The short term frequency variations in the output frequency that appear as energy at frequencies other than the carrier. It is usually expressed in terms of dBc or as an RMS frequency deviation in a specified frequency removed from the carrier. 

FPLANTS 

Future Public Land Mobile Telecommunications System 

Footprint

The particular patch of the Earth's surface reached by the signal from a communications satellite. 

Frame

A complete TV picture, comprising two fields. The North American transmission standard calls for 30 frames transmitted per second. 

Frequency

The number of cycles per second of an electromagnetic transmission. 1 hertz (Hz) = 1 cycle per second; 1 kilohertz (kHz) = 1,000; 1 megahertz (MHz) = 1,000,000; 1 Gigahertz (GHz) 1 billion. 

Frequency Modulation

A method of transmission in which the desired signal modulates (varies) the frequency of a "carrier" signal.

Frequency Accuracy

The maximum output frequency deviation from a specified tuning function under specified conditions. May be expressed in MHz, PPM, or PPM/°C.

Frequency Drift Over Operating Temperature, Max.

The maximum change in output frequency as a result of a specified change in operating temperature. In regard to the oscillators, a measure of the change in frequency over the specified operating temperature range. It is commonly expressed as parts-per-million per degree Celsius (PPM/°C) or as a percentage figure. From a system applications view, the frequency set at room temperature in +/- total parts per million.

Frequency Pulling

The difference between the maximum values of the oscillator frequency when the phase angle of the load impedance reflection coefficient varies through 360 degrees. Typically, this load impedance has a VSWR of 1.67:1.

Frequency Pushing

The incremental output frequency change produced by an incremental change in supply voltage (MHz/V). If supply voltage ripple, frequency range and amplitude are not specified, measurements will be conducted at a DC rate.

Frequency Range

Usually presented as the minimum and maximum frequencies between which a particular component will meet all guaranteed specifications.

Frequency response

The principal measures of the fidelity of any sound reproducing device.

Frequency Reuse

The use of the same frequency in different geographic areas by managing the propagation of the frequency. In cellular systems, their low power allows frequencies assigned to one channel to be limited to the boundaries of a signal cell. Therefore, the carrier is free to reuse the frequencies again in other cells in the system without causing interference. In satellite systems, the use of directional spot beams similarly allows non-overlapping geographic areas to reuse the same frequency, and the use of linear polarized signals allows the use of the same frequency within the same geographic area.

Fuzzy logic

A form of artificial intelligence, stored on a computer chip, that enables a camcorder or television to make complex adjustments in focus or picture quality based on ideal models.

Ft

Gain-Bandwidth Product - (also called transition frequency). It is the frequency at which the magnitude of the small-signal common-emitter current gain equals unity.

f3dB

Frequency at 3 dB Gain Point - The frequency at which gain has reduced 3 dB from the gain at a specified reference frequency.

G

Gain flatness

The variation of gain over a specified frequency range.

GA

Associated Gain - The tuned gain of a device when it is biased for optimum noise figure.

GaAs FET

Gallium Arsenide Field Effect Transistor - (also called GaAs MESFET for metal Epitaxial Semiconductor Field Effect Transistor). A field effect transistor with a reverse-biased Schottky-barrier gate fabricated on a gallium arsenide substrate. Roughly equivalent to a silicon MOSFET, GaAs FETs are depletion mode devices. Because charge carriers reach approximately twice the velocity as in silicon, for a given geometry a given gain can be reached at about twice the frequency.

Gain Block

A single stage of gain or a cascaded series of gain stages.

Gap

RF gap in RF cavities.

Geostationary orbit

The orbit of a communications satellite that allows it to move at the precise speed at which the Earth is rotating, thus remaining at the same spot in the sky relative to the Earth. The orbit is 35,900 km (22,300 mi.) above the Earth and directly over the equator.

GHz

Gigahertz (billions of hertz).

Gmax

Maximum Available Gain - The gain achieved when a transistor is unconditionally stable and the input and output ports are simultaneously conjugately matched. Also designated MAG.

GPS

Global Positioning Satellite

Group Delay

The time required for a signal to pass from input to output.

GSM

Global System for Mobile Communications, or Group Special Mobile - the Pan-European digital cellular standard

G1dB

1 dB Gain Compression Point - The level of gain from a device which is 1 dB less than the gain measured under small-signal conditions for a given input level. See also P1dB.

H

Handoff

Cellular systems are designed so that a phone call can be initiated while driving in one cell and continued no matter how many cells are driven through. The transfer to a new cell, known as a handoff, is designed to be transparent to the cellular phone user. During a cellular conversation, when the user reaches the edge of the service area of a cell, computers in the network assign another tower in the next cell to provide the phone with continuing service.

Harmonic Intermodulation Distortion

The ratio (in dB) of distortion to the IF output waveform caused by mixer-generated harmonics of the RF and LO input signals. This characteristic is extremely dependent on input frequency, RF and LO signal levels, and the precise impedance characteristics of all terminations at the operating frequency.

Harmonic Signals

Signals which are coherently related to the output frequency. In general, these signals are integer multiples of the output frequency.

HBT

Haterojunction Bipolar Transistor Technology

HDTV

High-definition TV, a technology aimed at producing a video picture containing as much detail as a 35-mm motion picture, with a wide-screen aspect ratio and stereophonic sound.

Hertz

The unit of measuring frequency signals (one cycle per second).

Hybrid (Junction)

A transformer or waveguide circuit having four terminals (or four ports) so arranged that a signal entering at one terminal will divide and emerge from the two adjacent terminals but will be unable to reach the opposite terminal. Hybrid Junctions (quadrature hybrids) are widely used in microwave circuits as power dividers and combiners (e.g., in balanced amplifiers, double-balanced mixers).

Hybrid Integrated Circuits

The combination of thin-film or thick-film circuitry deposited on substrates with chip transistors, capacitors and other components. Thin-film construction is used for microwave integrated circuits (MICs).

Hysteresis (Electrical)

In regard to threshold detectors, an upward change in the threshold voltage to ensure positive switching activity.

Hysteresis (Magnetic)

The phenomenon causing the values of the magnetic flux density to lag behind the values of the magnetizing force so that the increasing and decreasing fields differ in magnitude. In regard to YIG-Tuned oscillators, a magnetic lag effect of the magnetic components of a YIG device that occurs when the tuning coil current is changed. Hysteresis is measured in terms of the maximum resulting frequency difference at a particular magnet current when the device is turned from high to low frequency range.

I

I dB Gain Compression

(1 dB GCP, Gain Compression Point, P1dB) - The maximum output power of an amplifier at which amplification is nearly linear (high power levels result in compression). As input power applied to an amplifier is increased, some point will be reached where a 10 dB increase in input signal results in only 9 dB of output signal increase - this is the 1 dB gain compression point. Other compression points such as 0.1 dB or 2 dB are sometimes specified.

IDLC

Integrated Digital Loop Carrier

IF (Intermediate Frequency)

In superheterodyne receiving systems, the frequency to which all selected signals are converted for additional amplification, filtering and eventual direction.

Image-Reject Mixer

(or Image-Rejection Mixer) - A form of branched mixer in which the two output frequencies (LO + Fin LO - Fin) are separated, isolated and brought out to separate ports. Thus, as its name implies, this mixer configuration rejects the undesired mixer image.

Impedance

Opposition or resistance to the flow of electrical current. Impedance is the term used in non-direct current (DC) applications, while resistance is used for DC.

Incidental FM

The peak-to-peak variations of the carrier frequency due to external variations with the unit operating at a fixed frequency at any point in the tunable frequency range.

Initialization

Refers to the simple procedure of telling a new GPS receiver "where it is", when it is turned on for the first time. Information required includes: approximate present position in latitude/longitude coordinates; and the current local time and date.

Insertion Loss

The transmission loss measured in dB at that point in the passband that exhibits the minimum value.

Integrated Spurious Output Power

The total power of all spurious outputs in and out of the specified frequency range.

INTELSAT

International Telecommunications Satellite Organization; 112-member consortium of countries formed (1964) to launch and operate communications satellites.

Intercept Point

A figure (expressed in dBm) that indicates the linearity and distortion characteristics of a microwave component. It represents the point where the fundamental output and spurious responses (usually third-order) intersect, when plotted on a log-log scale with output power ordinate and input power as abscissa.