""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/Adaptor
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

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.

Intercept Point 3rd Order
Third Order Intercept Point (IP3) - The intersection point of the fundamental Pout vs. Pin extrapolated line and the third-order intermodulation products extrapolated line. IP3 is highly dependent on the LO and RF frequency, the LO drive level, and the impedance characteristics of all terminations at the operating frequency.

Interconnection
The conductive path required to achieve connection from a circuit element to the rest of the circuit.

Interconnections
Those connections of conductors made within a circuit on the same substrate.

Ion Implantation
A method of semiconductor doping in which selected dopants are ionized and accelerated at high velocity to penetrate the semiconductor substrate and become deposited below the surface.

IP3
Third Order Intercept Point or Intercept Point 3rd Order

IS-41
Interim Standard 41 - the cellular inter-system handoff and cell delivery

IS-54
Interim Standard Number 54, the dual-mode (analog and digital) cellular standard in North America. In the analog mode, IS-54 conforms to the AMPS standard.

ISDN
Integrated Services Digital Network. A switched network providing end-to-end digital connectivity for simultaneous transmission of voice and data over multiplexed communications channels.

ISM
Industrial, Scientific, and Medical. It is the unlicensed radio band in North America and some European countries. It is also refereed to as part 15.247, the FCC regulation that defines the parameters for use of the ISM bands in the United States, including power output, spread-spectrum, and noninterference.

ISO
International Standards Organization

Isolation
The ratio (in dB) of the power level applied at one port of a mixer to the resulting power level at the same frequency appearing at another port. Commonly specified isolation parameters of mixers are:
1. LO to RF port: The degree of attenuation of the LO signal measured at the RF port with the IF port properly terminated.
2. LO to IF port: The degree of attenuation of the LO signal measured at the IF port with the RF port properly terminated.
3. RF to IF port: The degree of attenuation of the RF signal measured at the IF port with the LO port properly terminated.
Normally the inverse isolation characteristics (such as RF to LO, IF to LO, and IF to RF) are essentially equivalent in a double-balanced mixer.

Isolator
A device that permits microwave energy to pass in one direction while providing high isolation to reflected energy in the reverse direction. Used primarily at the input of communications-band microwave amplifiers to provide good reverse isolation and minimize VSWR. Consists of microwave circulator with one port (port 3) terminated in the characteristic impedance.





J
Jamming (Military)
The deliberate radiation, re-radiation or reflection of electromagnetic energy with the object of impairing the use of electronic devices, equipment or systems by the enemy. Equipment may consist of rudimentary CW or noise transmitters, broadband transmitters or complex systems that generate deceptive signals.





K
kHz
Kilohertz (thousands of hertz).

Ku-band
The portion of the microwave spectrum (12,000-18,000 MHz) used in many newer video satellite transmissions, particularly in Direct Broadcast Satellite (DBS) systems designed for home reception.





L
LED
Light-emitting Diode: Solid-state devices that glow when electric current is applied.

Limiting Amplifier
Relating to analog signals and their processing. Also refers to the operating range of an amplifier where little or no distortion occurs.

Limiting Level
The input power level at which the input/output characteristics exhibit compression (i.e., the transfer function becomes nonlinear in that the output increases less than 1 dB for a 1 dB increase in input).

Linearity
Any deviation from a best fit straight line approximation under specified conditions. In regard to YIG-tuned and voltage-controlled oscillators, the maximum output frequency deviation from a best fit straight line approximation of the tuning curve under specified load and constant temperature conditions. In regard to YIG-tuned filters, the maximum deviation (in MHz) of the measured resonant frequency vs. coil current curve from the ideal linear tuning line over the YIG filter's operating frequency range.

LO
Local Oscillator - An oscillator used in superheterodyne receiver which when mixed with an incoming signal results in a sum or difference frequency equal to the intermediate frequency of the receiver.

LPTV
Low-power TV; TV station with limited broadcasting range, often built in rural areas in order to pick up and amplify distant signals. Also used for broadcast programming to specific audiences.





M
MAG
Maximum Available Gain - Gain at a frequency where the transistor is unconditionally stable (k>1) and the input and output ports are simultaneously, conjugately matched. Also designated: GZ(max), G(max).

Magnetic Susceptibility
The output frequency deviation due to magnetic field measured in kHz/Gauss.

MATV
Master antenna television; a distribution system in which a single antenna is used to feed broadcast TV signals to the occupants of a building or development. SMATV provides the same service but uses a dish antenna to pick up satellite transmissions.

MDS/MMDS
Multipoint distribution service; a method of distributing video programs from a central high point (usually a tall building) by microwave to subscribers equipped with special antennas. Sometimes called 'wireless cable.'

Mechanical Tuning
Maximum output frequency deviation that can be achieved without significantly affecting dielectrically stabilized oscillator characteristics. This is achieved by adjusting the air gap spacing between the dielectric resonator and tuning screw located directly above the resonator. Typically, mechanical tuning range is +/-1% of the center frequency.

Metropolitan Statistical Area
An MSA denotes one of the 306 largest urban population markets as designated by the U.S. government. Cellular operators are licensed in each MSA.

MHz
Megahertz (millions of hertz).

MIC
Microwave Integrated Circuit - In the microwave industry, a hybrid using thin- or thick-film conductors and passive components on a ceramic substrate combined with chip-form active and passive components.

MICamp
Microwave Integrated Circuit Amplifier

Microstrip
(Microstripline) A transmission line consisting of a metallized strip and a solid ground plane metallization separated by a thin, solid dielectric. This transmission line configuration is used since it permits accurate fabrication of 50 transmission line elements on a ceramic or PC board substrate.

Microwaves
High frequency radio waves lying roughly between infrared waves and radio waves (above 1 GHz = 1 billion cycles per second). Microwaves are generated by electron tubes, such as the klystron and the magnetron, or solid state devices with built-in resonators to control the frequency or by oscillators. Microwaves have many applications for radio, television, radar, test and measurement communications, distance and location measuring, and more.

MIPS
Million Instructions Per Second

Mixer Ports
The input/output terminals of a mixer, are identified as RF, LO and IF. In most double balanced mixers, the LO and RF are either transformer or transmission line-coupled to the mixer diodes, and therefore have a limited low-frequency response; while the IF port is usually direct-coupled with an essentially unlimited low frequency response. In upconverting applications, the low frequency input signal is often applied to IF port with the higher-frequency output signal being taken from the RF port.

Mixing
The generation of sum and difference frequencies which result from applying two AC wave forms to a non-linear circuit element. In mixer applications, with a signal of frequency Frf applied to the RF port and a signal fLO applied to the LO port, the resulting signal at the IF port will consist of two carriers (or sidebands) of frequencies Frf + fLO and Frf - fLO with internally-generated LO and RF harmonics.

MMIC
Monolithic Microwave Integrated Circuit designed using either silicon or GaAs devices.

Mobile Telephone Switching Office (MTSO)
The MTSO is the central computer that connects a cellular phone call to the public telephone network. The MTSO controls the entire system's operations, including monitoring calls, billing, and handoffs.

Modem
Modulator/Demodulator; a device that incorporates both in a single package.

Modulation or Tuning Sensitivity
The slope or the first derivative of the tuning curve in MHz/V. Where necessary, the fine gain or incremental slopes and the ratio of the slope should be specified over the frequency range.

Modulation or Tuning Sensitivity Variation
The charge in the first derivative as a function of tuning voltage and/or frequency. Usually specified as percentage change of the first derivation over an incremental frequency range. Direction of tuning for measurement should be specified. Also may be specified as the ratio of the maximum to minimum value of the first deviation.

Modulation Response Bandwidth
The modulation frequency range where, for a reference deviation bandwidth, all included modulation frequencies of equal amplitude will result in no less than a ratio of 1.414 (3 dB) of minimum to maximum deviation. The types of modulation should be specified as well as the internal impedance of the modulation source.

MTBF
Mean Time Between Failure - A calculated figure representing the estimated average lifetime of a device before it fails.

Multipath
Reception of one or more reflected signals along with a direct broadcast signal, producing distortion in stereo FM and ghost images in televisions

Multiplex
A method of accommodating two channels of information on one carrier.

Multiplexing Receiver
GPS receiver that rotates a small number of channels to multiple satellites in order to provide current positioning data. Typically, multiplexing receivers require more time for satellite acquisition and lock on, and are not as accurate as parallel channel receivers. Multiplexing receivers are also more prone to lose satellite fix in dense woods compared to parallel channel GPS receivers.





N
N-AMPS
Narrowband Advanced Mobile Phone Services

Narrowcasting
Transmission to a specific, small audience (such as Japanese speaking people for example), often via low-power, UHF stations.

Network Analyzer
A microwave test system that characterizes devices in terms of their complex small-signal scattering parameters (S-parameters). Measurements involve determining the ratio of magnitude and phase of input and output signals at the various ports of a network with the other ports terminated in the specified characteristic impedance (generally 50 ohms) - See ANA

Noise Figure (NF)
The ratio (in dB) between the signal-to-noise ratio applied to the input of the microwave component and the signal-to-noise ratio measured at its output. It is an indication of the amount of noise added to a signal by the component during normal operation. Lower noise figures mean less degradation and better performance.

Noise Floor
The lowest input signal power level that will produce a detectable output signal from a microwave component, determined by the thermal noise generated within the microwave component itself. The noise floor limits the ultimate sensitivity to the weak signals of the microwave system, since any signal below the noise floor will result in an output signal with a signal-to-noise ratio of less than one and will be more difficult to recover.

Noise Temperature
The amount of thermal noise present in a system. Used in microwave communications and sometimes radar, it is the equivalent of noise figure expressed in Kelvins (e.g., an amplifier with 1.5 dB noise figure has an effective noise temperature of 120 K).

Non-Harmonic Signals
Signals which are not coherently related to the output frequency.

Non-Operating Signal Rejection
The amount of signal rejection (in dB) referenced to the insertion loss, measured at any point across the frequency range with zero current through the tuning coil.

NRE
Non-Recurring Engineering - Charges made to a customer to pay for the engineering costs required to develop a custom part or to modify a standard part to meet special customer-specified characteristics. May be charged in a lump sum or spread over the production run.





O
Off Resonance Isolation
The amount of signal rejection (in dB) referenced to the passband minimum insertion loss measure data point outside the YIG filter passband skirts.

Off Resonance Spurious
The amount of suppression (in dB), referenced to the passband minimum insertion loss, of spurious responses outside the YIG filter passband skirts.

Oscillator Load
The maximum VSWR seen by the oscillator at the output port, referenced to 50°.

Output Frequency
The frequency of the desired output of the component. The undesired frequency components may include harmonics, subharmonics, 3/2 harmonics or nonharmonic spurious signals.

Output Power
The minimum and/or maximum output power at the output frequency under all specified conditions. Usually the specified conditions are temperature, load, VSWR and supply voltage variations. It is typically expressed in dBm or milliwatts (mW).





P
P1dB
Output Power at 1 dB Gain Compression - Essentially the maximum output power available from the transistor while providing linear amplifications. Also designated: PO-1 dB, and in numerous other ways. See also G1dB.

PA
Power Amplifier.

Package
The container for a circuit and/or component(s) with terminals to provide electric access to the inside of the container. In addition, the container could provide hermetic and environmental protection for, and a particular form factor to, the assembly of electronic components.

Pad
A metallized area on the surface of an active substrate as an integral portion of the conductive interconnection pattern to which bonds or test probes may be applied.

PAL
Phase Alternation Line color system, the color TV broadcast standard used in most of Western Europe and. in modified form, in China and Brazil.

Parallel Channel Receiver
GPS receiver that simultaneously tracks multiple satellites to provide the fastest, most reliable and accurate navigational data, under the most adverse conditions.

Passband Ripple
The peak to peak value (in dB) of ripple occurring within the 3 dB passband referenced to the minimum insertion loss.

Passband Spurious
The additional transmission loss (in dB) within the 3 dB passband attributable to the presence of spurious resonance (absorption) modes. Skirt spurious modes are referenced to a line tangent to the YIG filter passband skirt. Spurious modes within the minimum loss (ripple) region are referenced to the normalized filter response curve.

Passband Temperature Drift
The change in resonant frequency (at a fixed coil current) associated with the change in operating temperature.

Passband VSWR
The best VSRW as measured at any point within the 3 dB passband.

Passivation
The formation of an insulated layer directly over a circuit or circuit element to protect the surface from contaminants, moisture or particles.

PCMCIA
Personal Memory Card International Association

PCN
Personal Communications Network

PCB
Printed Circuit Board

PCS
Personal Communications System

PDA
Personal Digital Assistant

Percent Bandwidth
(2[f2-f1]/[f2+f1]) x 100 where f1 and f2 are the lower and upper endpoints, respectively, of the frequency range.

Perceptual coding
An approach to digital coding that records only the portions of sound or picture: that we believed to be audible or visible.

Personal Communications System
Used in Canada to describe next-generation digital cellular service. Also used to describe a loosely defined future ubiquitous telecommunications service that will allow "anytime, anywhere" voice and data communication with personal communications devices.

PHP
Personal Handy Phone. It is Japan's standard for digital cordless telephones.

Photo Etch
The process of forming a circuit pattern in metal film by light hardening a photo sensitive plastic material through a photo negative of the circuit and etching away the unprotected metal.

PIN diode
A diode made by diffusing the semiconductor so that a thin intrinsic layer exists between the P and N-doped regions (positive-intrinsic-negative). Such diodes do not rectify at microwave frequencies but behave as variable resistors controlled by the applied DC bias.

Pinhole
Small holes occurring as imperfections which penetrate entirely through the film elements, such as metallization films or dielectric films.

Pixel
A picture element; the "building blocks" of a liquid crystal display (LCD). The greater the number of vertical and horizontal pixels, the better the screen resolution and detail.

Plotter Display
Provides an overhead "bird's eye" view of current position relative to the waypoints and event marker/icons previously saved. A dotted line marks the shortest route to the chosen waypoint, and a recorded plot trail displays the path taken so far.

POPS
Short for "population". If the covered area of a cellular carrier includes a population base of 1 million people, it is said to have 1 million POPS. The financial community uses the number of potential users as a measuring stick to value cellular carriers.

Position Display
One of the primary navigational data screens that emphasize the present position latitude/longitude coordinates, as well as other helpful navigational information.

Post Tuning Drift
The maximum change in frequency ( fPTD) from the frequency measured at the beginning of the time interval (t1). The time interval (t1-t2) shall be referenced to the application of a tuning command (t0). The period of measurement ends at time (t2).

Power Amplifier
The final stage of amplification in a radio, the purpose of which is to raise the signal to the level required by the antenna system.

Power Divider
A passive resistive network that equally divides power applied to the input port between any particular number of output ports without substantially affecting the phase relationship or causing distortion.

Power Output @ 1 dB Gain Compression
See 1 dB Gain Compression.

Power Output Variation or Flatness
The maximum peak to peak power variation at all output frequencies in the tunable frequency range under all specified conditions.

Preform
To aid in soldering or adhesion, small circles or spares of the solder or epoxy are punched out of thin sheets. These preforms are placed on the spot to be soldered or bonded, prior to the placing of the object to be attached.

Present Position
Current location on the face of the Earth, in terms of the specific latitude/longitude coordinates, displayed in degrees/minutes/and thousandths of a minute.

Probe
A pointed conductor used in making electrical contact to circuit pad for testing.

Programmable Windows
The ability to customize existing split panel window groupings with specific combinations of navigational data.

PT
Total power dissipated in a transistor. PT=VCXIC+Pin(RF)-Pout(RF).

PTT
Post, Telephone, and Telecommunications. Administrative European government organizations responsible for mail and telecommunications services within their respective countries.

Pulse Amplifier:
Amplifiers specifically optimized and characterized for fast pulse droop and minimum overshoot - to handle complex input waveforms and pulse-modulating RF signals.





Q
Q
Generally a measure of the sharpness of the resonance or frequency selectivity of a tuned circuit or filter.

QPR
Quadrature Partial Response - A method of modulating a microwave carrier with two parallel streams of filtered digital bit streams carried in phase quadrature relationship. QPR normally uses 3-level partial response and occupies one-half the bandwidth of QPSK. QPR-7 uses 7-level partial response and occupies one-fourth the bandwidth of QPSK.

QPSK
Quadrature Phase Shift Keying (quadriphase) - A method of modulating a microwave carrier with two parallel streams of NRZ digital bit streams so that data is translated into 90° phase shifts of the carrier.

Quadrature
Having a characteristic 90° phase shift. Used to describe a coupler in which the two output signals are 90° out of phase, and in telecommunications for modulation techniques such as QPR and QPSK.

Quantization
The representation of a continuous quantity, such as a sound wave, by a series of numeric values.





R
Radio (RF)
System of communication employing electromagnetic waves propagated through space. Because of their varying characteristics, radio waves of different lengths are employed for different purposes and are usually identified by their frequency. The shortest waves are the highest frequency, or numbers of cycles per second; while the longest waves have the lowest frequency, or fewest cycles per second. In honor of the German radio pioneer Heinrich Hertz, his name has been given to the cycle per second: (hertz, Hz); 1 kilohertz (kHz) is 1000 cycles per second, 1 megahertz (MHz) is 1 million cycles per second, and 1 Gigahertz (GHz) is 1 billion cycles per second. Radio waves range from a few kilohertz to several Gigahertz. Waves of visible light are much shorter. In vacuum, all electromagnetic waves travel at a uniform speed of about 300,000 km (about 186,000 mi.) per second.
Radio waves are used not only in radio broadcasting but also in wireless devices, telephone transmission, television, radar, navigational systems, and communication. In the atmosphere the physical characteristics of the air cause slight variations in velocity, which are sources of error in such radio-communications systems as radar. Also, storms or electrical disturbances produce anomalous phenomena in the propagation of radio waves.
Because electromagnetic waves in a uniform atmosphere travel in straight lines and because the earth's surface is spherical, long distance radio communication is made possible by the reflection of radio waves from the ionosphere. Radio waves shorter than about 10 m (about 33 ft.) in wavelength - designated as very high, ultrahigh, and super high frequencies (VHF, UHF, and SHF) - are usually not reflected by the ionosphere; thus, in normal practice, such very short waves are received only within line-of-sight distances. Wavelengths shorter than a few centimeters are absorbed by water droplets or clouds; those shorter than 1.5 cm (0.6 in) may be absorbed selectively by the water vapor present in a clear atmosphere.
A typical radio-communication system has two main components, a transmitter and a receiver. The transmitter generates electrical oscillations at a radio frequency called the carrier frequency. Either the amplitude or the frequency itself may be modulated to vary the carrier wave. An amplitude - modulated signal consists of the carrier frequency plus two sidebands resulting from modulation. Frequency modulation produces more than one pair of sidebands for each modulation frequency. These produce the complex variations that emerge as speech or other sound in radio broadcasting, and in the alterations of light and darkness in television broadcasting.

Reseller
A middleman who buys at discounted wholesale rates or large volume and then resells them at retail prices.

Resonant Frequency or Passband Frequency
The arithmetic mean of the low and high normalized 3 dB frequencies.

Return Loss
When expressed in dB is the ratio of reflected power to incident power. It is a measure of the amount of reflected power on a transmission line when it is terminated or connected to any passive or active device. Once measured, it can be converted by equation to reflection coefficient that can be converted to VSWR.

RF
Radio Frequency - Generally referring to any frequencies at which the radiation of electromagnetic energy is possible. Also used as designation for frequencies at which the radiation of electromagnetic energy is possible. Also used as designation for frequencies below approximately 50 to 100 MHz (100 - 300 MHz is very high frequency, 300 MHz - 1000 MHz is ultra-high frequency, 1000 MHz and up is microwave).

RF cavity
Devices that operate at radio frequency, which are used to accelerate the beam. They operate by alternating an electric field across a gap (of which there are two in each RF cavity).

RF Leakage
RF Leakage is defined as the amount of energy which "leaks" from the connector and/or component. Although RF Leakage will vary with frequency, it is typically tested at only one frequency. Leakage, like Insertion Loss, is expressed in dB. Very large negative dB values indicate that the device does not radiate much energy.

Roaming
Using a cellular phone in a city other than the one in which you live.

Route
Consists of two or more waypoints combined in a course of travel. It provides the automatic capability to navigate through several waypoints, without having to reprogram the unit after arriving at each one. Once programmed into the GPS unit, the route provides the option of navigating forward through the waypoints or in reverse order.

Rural Service Area
The FCC divided the less populated areas of the country into 428 RSAs and licensed two service providers per RSA.





S
Satellite Status Display
An information screen that shows technical data about each satellite in view. Information includes receiver channel numbers; actual satellite ID numbers; status of satellite tracking (T) or searching (S); satellite elevations and azimuths; signal to noise ratios (SNR) (the higher the number, the better); and dilution of precision ratings (GDOP is most important; the smaller the number, the better potential accuracy).

Saturated
With respect to microwave components, indicates the maximum output power available when the component is driven beyond its linear region.

Saturated Output Power
The maximum output power of a component. As input power is increased, some point will be reached at which the output power will maximize. This is known as the saturated output power (PSAT) and typically occurs at approximately 5 dB gain compression.

Savable Plot Trails
The capability to save your actual plot trail crated on the plotter screen, thereby enabling the GPS user to either backtrack the course immediately, or save and retrace the trip at a later time.

Scrambling
A method of altering a cable or satellite transmission signal so that it can be seen only by those who own special decoders.

SECAM
Sequentiel Couleur avec Memoire (sequential color with memory); the color TV broadcast standard used in France and its former possessions and, in modified form, in the USSR and some Eastern European countries.

Selective Availability (S/A)
The system used by the U.S. Department of Defense to intentionally degrade the accuracy of satellite GPS signals being transmitted to civilian GPS receivers. All brands of civilian GPS receivers are equally affected by S/A. With random S/A on, the government has guaranteed that civilian GPS accuracy levels will consistently be 100 meters or less, 95% of the time. If S/A is turned off, those accuracy levels will improve to 10 to 15 meters consistently.

Selectivity
A measure of a tuner's ability to receive stations at closely spaced frequencies without mutual interference.

Sensitivity
The normalized change in YIG component's center frequency resulting from a change in tuning coil current, specified in MHz/mA.

Settling Time
The time (tst) required for the output frequency to enter and stay within a specified error band (fst) centered around a reference frequency (fr) after application of a step input voltage (VCO) or current (YTO). The time (tr) shall be specified for determining the reference frequency (fr). The period of measurement ends at the reference time (tr)

Skirt (Bandpass)
The portions of the passband curve above the upper and below the lower frequency points at which full off-resonance isolation is achieved.

Skirt Spurious
The amount of additional transmission loss, referenced to the normalized filter skirt curve, outside the 3 dB passband, caused by the spurious resonance (absorption) modes.

Slew Rates
The rate that the oscillator frequency can change in response to a step input waveform should be specified.

Small Signal Gain
The gain characteristics of an amplifier operating in the linear amplification region. Small signal gain is typically measured at least 10 dB below the input power level that creates 1 dB gain compression.

Small Signal Gain Flatness
Small signal gain deviation (stated as + and - and not p-p) from a flat reference line measured over the operating frequency of the amplifier at a fixed temperature.

SMR
Specialized Mobile Radio. A private business service using mobile radiotelephones and base stations communicating via the public phone network.

S/N or SNR
Signal-to-Noise Ratio - The ratio of signal power to noise power in a specified bandwidth, expressed in dB.

Speed Over Ground (SOG)
Digital reading that indicates current ground speed. (Selectable in miles per hour, knots or kilometers per hour).

S-Parameters
Scattering Parameter - Scattering parameters are a group of measurements taken at different frequencies which represent the forward and reverse gain, and the input and output reflection coefficients of a microwave component when the input and output ports of the component are terminated in a specified impedance - usually 50 ohms.
Magnitude - The length of the vector in the polar plane.
Angle - The direction of the vector in the polar plane.
dB - 10 log 10 (Power)
S11 - S-parameter input reflection coefficient - Expresses the magnitude and phase of the input reflection coefficient, measured with the input and output ports terminated in a pure resistance of 50 ohms.
S21 - S-Parameter forward transfer coefficient - Expresses the forward voltage gain magnitude and phase, measured with the input and output ports terminated in pure resistance of 50 ohms.
S12 - S-parameter reverse transfer coefficient - Expresses the reverse voltage gain (sometimes called isolation) magnitude and phase, measured with the input and output ports terminated in a pure resistance of 50 ohms.
S22 - S- parameter output reflection coefficient - Expresses the magnitude and phase of the output reflection coefficient, measured with the input and output ports terminated in a pure resistance of 50 ohms.

Specification Temperature Range
The range of temperatures as measured near the component or device must meet all guaranteed specifications unless otherwise noted.

Spectrum
The complete range of electromagnetic waves that can be transmitted by natural sources such as the sun, and man-made radio devices. Electromagnetic waves vary in length and therefore have different characteristics. Longer waves in the low-frequency range can be used for communications, while shorter waves of high frequency show up as light. Spectrum with even shorter wavelengths and higher frequencies are used in X rays.

Spread-Spectrum
Originally developed by the military, spread spectrum radio transmission essentially "spreads" a radio signal over a very wide frequency band to make it difficult to intercept and difficult to jam.

Spurious-Free Dynamic Range
The range of input signals lying between the tangential sensitivity level and an upper signal level at which generated in-band spurious outputs exceed the tangential level.

Spurious Signal and Outputs
Undesired signals produced by an active microwave component, usually at a frequency unrelated to the desired signal or its harmonics. Spurious outputs are both harmonically and non-harmonically related signals. Their tolerable amplitude should be specified within and out of the frequency range of the oscillator. Typical values range from -60 dBc to -80 dBc.

SS7
Signaling System 7 Protocol

SSB Conversion Loss
In most applications, only one of the signals (fRF+fLO) or (fRF-fLO) appearing at the IF port of a mixer is of interest; therefore, only one of these signals (or sidebands) is considered when determining conversion loss in 3 dB higher than the conversion loss when both sidebands are considered (double sideband conversion loss).

Steering Screen
Shows a graphic "highway view" of the GPS user's course over ground. Provides helpful instructions as to how far off course, which direction to steer, right or left, to make corrections, and displays related navigational data pertaining to the waypoint.

Straight Line Navigation
The standard method of navigation used by recreational GPS products. When commanded to "navigate to a waypoint", the unit draws a straight, dotted line from the present position to the selected waypoint. It's the shortest, most direct route to the destination. Caution: Straight line navigation does not take into account any obstacles in the path; interim waypoints may be required to navigate safely around obstacles.

Stripline
A transmission line consisting of a conductor above or between extended conducting surfaces.

Substrate
The wafer of ceramic on which the thin-film circuit is deposited in hybrid microwave integrated circuit construction.

Suppression
The minimization of undesired side effects in circuit operations (e.g., two tone intermodulation suppression, usually through a design compromise or the addition of specialized components).





T
TA
Ambient Temperature - TA is usually room temperature and is normally assumed to be 25°C if not otherwise specified.

TCASE
Case Temperature - The external temperature of the component package. This temperature is higher than the ambient temperature due to the power dissipation of the device.

tD
Group Delay - The time required for a signal to pass from input to output.

TDMA
Time Division Multiple Access

Termination
A circuit element or device such as an amplifier, divider, resistor, antenna, etc., placed at the end of a transmission line.

THD
Total Harmonic Distortion; A measure of all of the spurious signals added by a sound-reproducing device.

Thermocompression Bonding
See: Wedge Bond

Thin Film
A thin-film (usually less than 10,000 Angstroms thickness) deposited onto substrate by an accretion process such as vacuum evaporation, sputtering or pyrolytic decomposition.

TIA
Telecommunications Industry Association. The North American organization established to provide industry wide standards for telecommunication.

Time Division Multiple Access
The cellular industry established a TDMA digital standard in 1989. TDMA increases the channel capacity by chopping the signal into pieces and assigning each one to a different time slot. Current technology divides the channel into three time slots, each lasting a fraction of a second, so a single channel can be used to handle three simultaneous calls.

Time To Go (TTG)
Digital reading showing the time remaining from current position to the next waypoint. This function takes into account Distance To Go (DTG), and Velocity Made Good (VMG) to give as closely as possible the amount of time left to reach the waypoint. Displayed in hours, minutes and seconds, it will continue counting down until the waypoint is reached.

TJ
Junction Temperature - The temperature of the emitter-base junction of a transistor.

TJ(MAX)
Maximum Junction Temperature - Maximum allowable transistor junction temperature. It is normally 200°C for silicon for high reliability.

"TO" Package
One of several metal hermetic "cans" originally developed as transistor packages.

TR453
Cellular Digital Standard Committee under TIA

Transition
A waveguide device used to convert from waveguide to coaxial transmission lines.

Transmission Line
The conductive connections between circuit elements that carry signal power. Wire, coaxial cable and waveguide are common examples.

Transponder (satellite)
One communications satellite "channel" consisting of an uplink receiver, intermediate signal processing components and downlink transmitter. One transponder may be configured to carry many different signals.

True and Magnetic North
True north is the top of the world, where all lines of longitude converge. Magnetic north is the location our compasses point to; it lies several hundred miles to the south of true north, in Arctic Canada.

TSTG
Storage Temperature - The maximum ambient temperature at which a non-operating transistor may be stored without damage.

TVRO
Television Receive Only- Small satellite earth stations designed to receive satellite relayed television programming having no provision for transmitting to the satellite.

Tuning Input Impedance
The small-signal impedance seen at the tuning input port at a specified modulation frequency or frequencies.

Tuning Monotonicity
Continuously increasing or decreasing output frequency for a continuously increasing tuning voltage f(V1)(fV2) for V1V2.

Tuning Repeatability
The ability of the oscillator to repeat a frequency within specified limits, f, when the original command voltage is reapplied after having been commanded through an arbitrary tuning history. The repeatability window f equals ft1-ft2 with constant tuning voltage over the time interval t1 to t2. Temperature stability and dwell time are to be specified.

Tuning Response Time
The time required for the filter response to come within a specified value of the desired frequency for a specified frequency sweep.

Tuning Sensitivity
The slope of the tuning curve in MHz/mA.

Two-Tone, Third-Order Intermodulation Distortion
The total amount of distortion (dB relative to desired waveform) to the output signal waveform that exists when two simultaneous input frequencies are applied to the RF port of a mixer. Two-tone, third-order intermodulation distortion products are described by 2fR2-Fr1+/- fLO and by 2fR1-Fr2+/- fLO. The higher the third-order intercept point and conversion compression of a mixer, the lower the intermodulation for given input signals will be.





U
Ultrasonic Bonding
A process involving the use of ultrasonic energy and pressure to join two materials.

Uplink
The earth-to-satellite microwave link and related components such as earth station transmitting equipment. The satellite contains an uplink receiver; uplink components in the earth station are involved with the processing and transmission of signal to satellite.





V
Varactor
A diode which, when operated in a reversed-biased condition, provides a junction capacitance that varies with applied voltage. Used as an "electrically variable" capacitor in tuned circuits (such as those in varactor-tuned oscillators) or as frequency multiplier.

Velocity Made Good (VMG)
Digital speed reading (similar to SOG) that compensates for progress being made toward a waypoint. For example, when traveling directly on course toward a waypoint, the SOG and VMG readings may match. However, when traveling off course, the VMG reading will typically be slower than the SOG. VMG is a true indication of the speed being made to selected waypoint.

Vertical Blanking Interval
VBI - The 21 lines between TV frames, transmitted, like the frames, at a rate of 30 times per second. These lines are used for auxiliary information, including teletext, closed captions, and test signals.

Void
Any region in the metallization exposing oxide, that was not caused by a scratch.

VPE
Vapor Phase Epitaxy (epitaxial) - An epitaxial layer on a transmitter wafer or chip formed by condensing a single-crystal layer of semiconductor material on the surface of the wafer.

VSWR
When impedance mismatches exist, some of the energy transmitted through will be reflected back to the source. Different amounts of energy will be reflected back depending on the frequency of the energy. VSWR (Voltage Standing Wave Ratio) is a unitless ratio ranging from 1 to infinity, expressing the amount of reflected energy. A value of one indicates that all of the energy will pass through, while any higher value indicates that a portion of the energy will be reflected.





W
Wafer
A single slice of substrate material (silicon or gallium arsenide) upon which many transistors are fabricated. The wafer is then tested, scribed and broken apart to produce transistor chips.

Watt
A unit of electrical or acoustical power. Electrical power is the product of voltage and current. Acoustical power is proportional to sound-pressure intensity.

Waveguide
A transmission line specific to microwave communications consisting of a conducting metal outer shell, and filled with air or a vacuum. Waveguide is also used as the basis for numerous components such as crossguide couplers, filters, hybrid combiners and circulators/isolators.

Waypoint
Location, spot or destination (latitude/longitude) that can be stored in memory to be recalled and used at a later time for navigation purposes. Simply think of it as an "electronic address".

Wedge Bond
A bond between a gold wire and a gold metallized substrate using a wedge-shaped tool. Thermocompression boning combines temperature and pressure to make a wedge bond. Ultrasonic bonding combines ultrasonic energy with the pressure of the tool.

WAN
Wide Area Network

Wilkenson Combiner
(Wilkenson splitter) - An equal-phase power splitting/combining circuit used as an alternative to quadrature hybrid couplers in some balanced amplifier designs. Tends to have narrower operating bandwidth than quadrature coupler.

Wire Bond
Includes all the constituent components of wire electrical connection such as between the terminal and the semiconductor die. These components are the wire, metal bonding surfaces, the adjacent underlying insulating layer (if present) and substrate.

WLAN
Wireless local area network. A computer network that allows the transfer of data and the ability to share resources, such as printers, without the need to physically connect each node with wires. WLANs may also offer mobility within an office or similar environment.

WPBX
Wireless private branch exchange. The WPBX offers business users the ability to make and receive calls using cordless telephones anywhere on a company's premises.





X
X.25
CCITT Specification & Protocol for Public Packet-Switching Networks - Layer 3



Y
YIG
Yttrium-Iron Garnet is a synthetic crystalline ferrite containing yttrium and iron (Y3Fe6O16). If a single crystal sphere of YIG is immersed in a magnetic field, and RF energy is coupled into it via a magnetic loop, the crystal will resonate at a frequency linearly proportional to the magnetic field strength. In practical YIG-tuned oscillators and filters, the magnetic field is derived from an electromagnet and the resonant frequency of the YIG sphere is proportional to the current flowing through the magnetic coil.

YIG-tuned Filter
A microwave filter using YIG sphere as the resonant element.

YIG-tuned oscillator
A microwave tunable oscillator using the YIG sphere as the frequency determining element. YIG-tuned oscillators can be made with Gunn-diode technology or, add an internal buffer amplifier to minimize frequency pulling, and produce additional output power capability. YIG-tuned oscillators are fundamental oscillators; they do not contain frequency multiplication circuitry.


0-9
3 dB Bandwidth
The frequency span (in Mhz) between the points on the selectivity curve at which the insertion loss is 3 dB greater than the minimum insertion loss. Also called 3 dB passband