A

Accelerated Life Unique to Motorola, ALT is a proprietary Testing (ALT) process developed to simulate five years of field stress in several weeks. Motorola pagers are subject to this test in design, at pre-production, and during their product life cycle.

AF See Audio frequency.

AGC See Automatic gain control.

Alphanumeric A character set containing letters, digits, and other symbols such as punctuation marks.

Ambient Temperature in the area surrounding an temperatureobject.

Amplification Process of increasing the strength of a signal, current, voltage or power.

Amplifier Used to boost sound in analog systems.

Amplitude Magnitude or size. In waveforms (signals) occurring in data transmission, the voltage level is called the amplitude.

Analog Refers to a type of measurement in which the "line of measure" is continuous as compared to one which is discretely incremented. For example, a clock with hands is an analog device (as compared to a digital clock which is not). With the analog clock, time is measured smoothly with an infinite number of increments. A digital clock displays time only in the increments of its greatest resolution, usually seconds. You would be able to see the time 12:01:01.5 on an analog clock; the digital clock would show the time as either 12:01:01 or 12:01:02 but nothing in between.

Analog Transmission transmission of a continuously variable signal as compared to a discrete (digital) one.

Antenna Device which radiates and/or receives radio signals.

Antenna (Omni-directional) Antenna that radiates equal power in all directions in a horizontal plane.

Antenna(Uni-directional) Antenna that radiates most of its power in one direction.

Antenna gain Increase in power radiated by and/or received by an antenna in a given direction compared to the power radiated (or received) in the same direction by a "standard" antenna.

Attenuation Reduction in strength of an electrical signal.

Audio frequency Usually refers to that range of tones (frequencies) which the human ear can hear. Generally accepted as the range between 20 and 20,000 Hz (Hertz).

Automatic gain A circuit feature which maintains a control constant level of output signal automatically by varying the amount of amplification applied to an input signal of varying level.

Automatic retry Trunking term referring to the system's ability to "re-enter" or "redial" for the user in situations where the channel was originally busy or the user was in a fade area.

Bandwidth Portion of the frequency spectrum required to transmit desired information. Each radio channel has a centre frequency and additional frequencies above and below this carrier frequency which are used to carry the transmitted information. The range of frequencies from the lowest to the highest used is called the bandwidth.

Baseband Transmission of a digital or analog signal signalling at its original frequencies. The signal is in its original form, not changed by modulation.

Base station Transmitter/receiver unit situated in a fixed location which can talk directly to other radio units.

Battery One or more electrochemical storage cells connected together to serve as a source of DC power.

Battery saver Circuit used in some radios to extend the life of a charged battery.

Baud Unit of signalling speed in telegraphic code; also the number of bits per second that can be transmitted/received in a given computer system.

Bi-directional In two, usually opposite, directions. Frequently refers to the coverage pattern of a radio antenna which is most predominantly in two directions.

Binary Refers to the base-two number system. The system contains only two numbers, 0 and 1. In computer-like circuits, the presence of a voltage, current or other such signal indicates a "1" whereas the absence of the same signal indicates "0".

Bit Contraction of binary digit. It is the smallest unit of information in a binary system.

Bits per second (bps) Rate at which bits of information are transmitted.

Broadcast 1. Delivery of a transmission to two or more stations at the same time, such as over a bus-type local network or by satellite.
2. Protocol mechanism whereby group and universal addressing is supported.

Broadcast band Radio frequency range between 550 KHz and 1600 KHz in which all commercial AM broadcasting stations are assigned.

Capacity Average amount of traffic that a circuit or circuit group can handle.

Carrier Continuous frequency capable of being modulated, or impressed with a second (information carrying) signal.

Carrier frequency Radio wave, current, or voltage used for transmitting intelligence, usually the frequency of a radio channel.

Carrier squelch Feature that responds to the presence of an RF carrier by opening or unmuting (turning on) a receiver's audio circuit. A squelch circuit silences the radio when no signal is being received so that the user does not have to listen to "noise".

Cellular Type of mobile telephone service in which mobile telephone the geographic serving area is divided service into sub-regions (cells), each with its own antenna and switching node.

Cellular system Method of mobile telephone service which divides radio communication service areas into small "cells" or districts. The cellular approach utilizes low-power transmitters which allow uninterrupted communications through sophisticated switching equipment linking the cells. This system, by reusing frequencies and standardizing service and equipment, will substantially improve mobile telephone service.

Central control Unit which assigns a control channel and executes, transmits and receives logic programmes in a trunked radio system. The "brains" of a trunked system.

Channel Narrow band of frequencies (including the assigned carrier frequency) within which a radio system must operate in order to prevent interference with stations on adjacent channels.

Channel element Frequency-determining device for certain types of older radio equipment. Some transmitters and receivers use a quartz crystal to establish and maintain their opening frequency. Since a crystal's frequency is affected by changes in temperature, the channel element employs an electrical circuit which compensates for the changes.

Chip Small piece of specially prepared silicon material on which electronic circuits are etched to make an integrated circuit device.

Circuit Path through which electrical signals flow.

Conductor Solid, liquid or gas which offers little opposition to the continuous flow of electricity.

Console Desk-like "cabinet" that houses equipment and controls for a communications centre or station.

Conventional Non-trunked radio system. (radio system)

Conversion In receivers, the lowering in frequency (as a single/dual (converting) of a received signal so that conversion, etc) the contained intelligence can be more easily recovered. By example, in a dual conversion receiver, the received signal will first be converted to a high I.F. (intermediate frequency) of say 10.7 MHz. After simplification, a second conversion to 455 KHz (the low I.F.) takes place and from this signal the audio is recovered.

Coverage Expression of statistical probability relating to a customer's useable radio area and time. Unless otherwise defined, coverage is usually understood to permit communication within 90 percent of an area, 90 percent of the time.

Crystal Thin slab of natural or man-made quartz which, when subjected to the proper electrical excitation, will vibrate or oscillate at a specific frequency. Crystals can be used to control the operating frequency (as well as other functions) of a radio transmitter or receiver.

Current Movement or flow of electrons through a conductor. Electrical current is measured in amperes (amps).

Cycle One complete reversal of an alternating current consisting of a rise to a maximum level in one direction, the return to zero, a rise to a maximum value in the other direction and a return to zero. The number of cycles occurring in one second is the frequency of the current. The word "Hertz" is used to signify one cycle per second.

DB See Decibel.

DC control Type of remote control using DC signals for control of a radio system.

DC-coupled Type of electronic circuit which passes a direct current signal.

Decibel Unit of relative voltage, power or sound equal to one tenth of a bel. The key term in this definition is relative; the decibel is used to describe the difference in two values of voltage, power, etc. When relating sound, the decibel is roughly the smallest change in level which the human ear can detect.

Decoder Device that "receives" and translates coded intelligence into a usable form.

Decryption Process of "unscrambling" an encrypted or coded message.

Degradation Refers to the lessening of signal clarity.

Delay Time difference between initiation and response.

Demodulation Process of extracting the intelligence (message) from a modulated carrier signal.

Detector Stage or circuit in a receiver that demodulates the carrier signal (RF) into its audio form.

Digital Data (information) in the form of pulses.

Digital signal Transmission signal that carries information in a discontinuous stream of on/off pulses.

Dipole antenna Straight ungrounded antenna which is separated in the centre by an insulator and uses a conductor one-half wavelength long at a specified frequency.

Directional Any antenna which picks up or radiates antenna signals better in one direction than another.

Disable To make inoperative or to stop.

Discreet alert When pagers are in the silent position, they will receive pages but will emit only a short beep (or chirp).

Display Refers to the visual manner in which a message is depicted.

Distortion Unfaithful reproduction of audio signals due to changes occurring in the waveform of the original signal somewhere in the course of its transmission, reception, or amplification.

DTMF See Dual tone multi-frequency.

Dual tone multi-frequency Tone-based signalling scheme which combines two of a set of standard frequencies. The result of the combination is a third or "beat" frequency (signal) which is the desired or useable signal. DTMF signalling is used as "tone- dialling" in the common telephone.

Duty cycle Battery usage rating system for radio equipment which specifies the amount of transmit, receive and idle time for a specified use period. For example, "5-5- 90 = 8 hours" means that if the radio transmits 5% of the time, receives 5% of the time, and is idle 90% of the time, then the battery will last 8 hours.

Electronic mail Communication service that permits the electronic transmission and storage of text messages.

Encoder Converter or transducer used to create a specific addressed message.

Escalert alert tone Motorola term for a series of interrupted beeps which increase in volume until the pager is reset. This allows the pager to be used in a variety of noise environments.

Falsing Extraneous signal or signals that cause a decoding device to operate without the normal input of proper encoding signals.

FCC See Federal Communications Commission.

Federal Communication Commissions (FCC) Board of Commissioners appointed by the President which has the power to regulate domestic communications systems other than those owned and operated by the federal government itself.

Feedback The transfer of a portion of energy from one point in an electrical system to a preceding point. The transfer may be either electrical or acoustical.

Field Product feature enabling radio reprogrammable reprogramming of frequencies and features at a service shop rather than at the factory.

Filter Equipment that permits the transmission of certain frequencies while excluding others.

5/6-tone Paging code format utilizing 12 tones transmitted 5 or 6 at a time sequentially. If 6 tones are used, it indicates dual address operation.

FLEXTM High speed paging code format developed by Motorola that can move data at 6400 bps.

FM See Frequency modulation.

FM transmitter Radio transmitter that emits or radiates a frequency modulated signal.

Frequency Number of complete cycles per second of an alternating current signal, usually measured in hertz.

Frequency Method of modulating (adding modulation intelligence to) a transmitter's base or carrier frequency by causing the frequency to vary above and below the carrier frequency proportional to the inputted intelligence.

Frequency shift keying Modulation method which imparts intelligence to a radio carrier by slightly changing the frequency of the carrier above and below the channel frequency.

FSK See Frequency shift keying.

Gain antenna Antenna designed to increase its normal field range through a more directional profile. The increase is measured in decibels.

Gateway Important characteristics of a LAN that allows it to interface with different transmission networks, particularly the public switched telephone network. The interface mechanism provides special data translation and conditioning functions for transmission compatibility between the networks.

GHz See Gigahertz.

Gigahertz Unit of measurement of a frequency equal to one billion times per second. Frequencies in this range are usually considered to be the microwave type.

Golay High capacity binary paging code format also known as GSC (Golay Sequential Code); named after its inventor due to its superior fade resistance and error correcting capabilities.

Ground Connection (intentional or accidental) between an electrical circuit and the earth or its electrical equivalent.

Ground wave Radio wave that is propagated near or at the surface of the earth.

Group call Feature found in some paging systems which permits alerting of all units in a given group simultaneously. When used in combination with individual paging, the pager must be capable of responding to two different codes.

Harmonics Radio signals which are generated along with a desired signal. Harmonics are usually undesirable and must be eliminated or suppressed to a level which will not cause interference-type problems.

Hertz The unit of frequency measurement. Previously called "cycles per second".

High band Portion of the frequency spectrum from 132-174 MHz.

Hz See Hertz.

IF See Intermediate frequency.

Insulation Any non-conductive material used to prevent the leakage of electricity from a conductor, such as plastic, rubber or glass.

Integrated circuit Semiconductor device which may contain the equivalent of hundreds or thousands of transistors, diodes, resistors, and capacitors on a tiny "chip" silicon.

Interconnect Operational scheme or piece of electronic equipment which permits messages to be transferred between radio and telephone systems.

Interface Method or piece of equipment for interconnecting units or systems which may not be directly compatible.

Interference Effects that occur when undesired signals inhibit or degrade the reception of a desired signal.

Intermediate A range of frequencies which falls frequency between audio and radio frequencies.

Intermodulation Mixing of two radio signals to produce a third signal which interferes with the reception of a desired signal. Sometimes called "intermod".

Inverter Device which changes direct current to alternating current.

KHz See Kilohertz.

Kilohertz Measure of frequency. One kilohertz is equal to one thousand hertz (cycles per second).

Kilowatt One thousand watts.

KW See Kilowatt.

LCD See Liquid crystal display.

LED See Light emitting diode.

Light emitting A semiconductor indicator light. diode

Line Transmission wire within a telephone system; part of a local loop that connects a subscriber to the central office.

Line drop Voltage drop between two points on a power or transmission line, caused by the resistance of or leakage from the line.

Line-of-sight Straight line distance between two distance points; often refers to the distance from an antenna to the horizon.

Liquid crystal A type of information output or display display device used for watches, calculators, meters and similar devices.

Low band Portion of the frequency spectrum from 25-54 Mhz.

Megahertz Unit of frequency measurement equal to one million cycles per second.

Mem-o-lert (deferred paging) Feature enabling a pager to receive and store a page without sounding an alert; at a later time, depressing a switch on the pager retrieves the stored messages.

Message protection In certain Motorola pagers, important messages can be stored in memory until you turn off the pager. New messages will not overwrite protected messages.

MHz See Megahertz.

Microphone Device which converts sound waves into corresponding audio frequency electrical energy.

Microprocessor Solid state integrated circuit device which performs many high speed (digital) functions. The heart of computer-type circuits.

Microwave Portion of the frequency spectrum above one gigahertz (1,000 MHz).

Microwave radio Radio frequency used extensively for long-distance telephone transmission. Digitally-encoded messages are sent through microwave channels either between terrestrial antennae, via satellite, or through wave guides.

Mid-band Part of the frequency spectrum from 72-76MHz.

Modem Interface device usually connected between a computer and telephone lines or a radio system.

Modulate Vary the amplitude, frequency or phase of a radio signal in order to transmit intelligence.

Modulation Impressment of information on a carrier signal by varying one or more of the signal's basic characteristics — frequency, amplitude and phase. Different modulation carries the information as the change from the immediately preceding state rather than the absolute state.

Multiplex Method of imposing one or more subcarrier channels on the base frequency of a transmitter. Common in point-to-point microwave systems.

Nationwide paging Method of national or regional paging in which a single frequency is used throughout the nation (region) for sending messages to a paging system subscriber.

Network 1.Series of points connected by communications channels.
2.Switched telephone network is the network of telephone lines normally used for dialled telephone calls.
3.Private network is a network of communications channels confined to the use of one customer.

Networking Method of national or regional paging in which paging messages are sent via a communications network to various regions and transmitted, usually at different frequencies, in different areas.

Node Point in an electrical or electronic circuit which is the junction of two or more components.

Noise compensated Squelch system that responds to the squelch presence of an RF (radio frequency) carrier. Such a system usually permits adjustment of the squelch to allow only signals of a certain strength to be heard.

Non-volatileType of solid state "memory" device memory which retains its electrical data after power is removed from the circuit.

Numeric display Use of numbers to display channel selected.

Omni-directional Antenna that radiates or receives signals equally well from all directions.

Operator Person who assists in placing telephone calls. Out-of-range Optional feature of a pager that tells option the user that he/she is out of range of the message receiving capability of the unit.

Paging One-way communication concept in which an intended receiver is alerted to receive a message.

Paging format Paging format is similar to a computer language. Different pager manufacturers have designed their pagers to work with specialized formats or codes and carriers must use a paging terminal equipped with these codes.

PBX Abbreviation for private branch exchange. Private telephone switching system located on a customer's premises. Both PBX and hybrid PBX systems provide pooled access to a group of access lines typically by dialling "9" from an internal station set.

POCSAG Binary paging code format named after the committee which conceived it – the (British) Post Office Code Standardisation Advisory Group. Available in Motorola pager models.

Point-to-point Describing a circuit that connects two points directly, where there are generally no intermediate processing nodes or computers, although there could be switching facilities. A type of connection, such as a phone line circuit, that links two and only two logical entities.

Power Electrical measure of the strength of a transmitter's signal. Power is measured in watts.

Power amplifier Electronic unit operating in the audio or radio frequency bands which is designed to increase and deliver an increased amount of output energy (power). Sometimes the unit is referred to by its abbreviation, PA.

Power-up alert Feature of a radio receiver that permits tones the user to hear the start-up of the device.

Priority paging Pager "address" which has been designated as a "priority address". This designation overrides the unit's silent mode of operation.

Propagation Radiation of electromagnetic waves.

Protocol Rules of order by which a communication network is operated. Also the rules by which a specific data communications function must proceed.

PSTN See Public switched telephone network.

Public switched telephone network Domestic telecommunication network commonly accessed by ordinary telephones, key telephone systems, PBX trunks, and data arrangements.

Radio Telecommunications by means of radio communication waves.

Radio frequency That part of the general electromagnetic spectrum between the audio and infra- red light regions (about 10KHz to 10,000,000 MHz).

Radio receiver Unit which amplifies radio frequency signals, separates the audio signal from the RF carrier, amplifies it, and converts it back to the original sound waves (voice heard through the speaker).

Radio spectrum Entire range of useful radio waves as classified into seven bands by the Federal Communications Commission.

Radio wave Combination of electric and magnetic fields varying at a radio frequency rate and capable of travelling through space at the speed of light. It is produced by feeding the output of a radio transmitter into a transmitting antenna.

Range Extent of coverage or effectiveness of a transmitter or radio system. A measure of distance, usually in miles.

Read-only memory A semiconductor device capable of storing data which can only be read, not changed.

Receiver Device on the transmission line that converts a signal to whatever type of signal is needed to complete the transmission.

Reminder chirp Optional feature of a pager that emits a "chirp" every two minutes when there are unread messages.

Remote control Control of a radio system where all functions are performed at more than 100 feet from the base or control station. Control may be by DC or tone signals.

Remote Ability for the carrier to programme a programming pager into the paging terminal when away from the terminal location.

Repeater Type of radio station that automatically re-broadcasts radio signals that it receives. Repeaters are used to extend the effective range of communications.

RF See Radio frequency.

ROM See Read-only memory.

RS-232C Standard which describes a type of electronic interface between two devices. Sometimes referred to as a "serial" interface.

Satellite Orbiting system in space that receives communications radio signals from ground bases on earth and then re- transmits them to distant locations.

Scan Optional feature of a receiver that enables the unit to continuously check multiple channels for messages. Once it locks into a message being transmitted, it continues to look for another channel that is actively transmitting.

Selectivity Characteristic of responding to a desired frequency to a greater degree than to other frequencies.

Semiconductor Crystalline material which displays properties of both a conductor and an insulator. Used to make transistors, diodes, and integrated circuits.

Sensitivity Characteristic of a radio receiver which determines the minimum input signal strength required for a given signal output. In FM, sensitivity is usually measured in microvolts (µV).

Signal Form of a radio wave in relation to the frequency serving to convey intelligence in communication.

Silent alert Non-audible signal in a beeper. Usually a vibrating motor that causes the pager to "shake" silently to alert you. An option on many tone alert and digital display pagers. Perfect for use in private meetings where you do not wish pages to disturb the meeting, or in high ambient noise environments. Can also be a visual blinking light indicator.

Simulcasting Relates to simultaneous transmission of a paging signal from all the transmitters in a system to achieve wide-area coverage. Normally, without special simulcast engineering, such multiple transmissions would garble all the overlapping signals.

Spectrum Range of frequencies within which electromagnetic radiation has some specified characteristic, such as the audio-frequency spectrum, radio spectrum, ultraviolet spectrum, etc.

Squelch Electronic circuit which causes the audio output stages of a receiver to be turned off when a desired radio signal is not present.

Static Noise heard in a receiver due to changes in electrical charges in the atmosphere caused by lightning or man-made causes such as engine ignition, electric motors, neon lights, etc.

Subscriber Person(s) subscribing to a pager or mobile telephone service.

Switch Piece of equipment that establishes and routes communication paths between separate extensions.

Synthesizer Type of electronic circuit which generates signals; a replacement for a crystal oscillator circuit. The synthesizer is usually a programmable semiconductor device (integrated circuit) which permits control of the frequency of the output signal. Synthesizers are used in musical instruments, radio transmitters/receivers, test equipment (signal generators), etc.

Telecommunications Communication process that allows the transmission of information from a sender to a receiver by means of an electromagnetic or light wave medium.

Telephone Piece of equipment used for the general transmission of voice communications.

Telephony System of speech telecommunications.

Telocator alphanumeric paging protocol Similar to TNPP; supports interoperability across different alphanumeric paging terminal manufacturers.

Telocator network Signalling protocol developed and paging protocol supported by Telocator Network of America that supports interconnection of terminals from different manufacturers into wide-area paging systems.

Terminal Computer-controlled switching system network and controls the base stations used to signal pagers and mobile telephones. The software in the terminal dictates some of the capabilities of the pager or mobile telephone.

TNPP See Telocator network paging protocol.

Tone Type of telephone dialling that sends to the central office unique acoustic sound for each number pressed on the dial pad.

Touch-tone AT&T's registered trademark for push- button (DTMF) dialling.

Transceiver Terminal that transmits and receives traffic.

Transmission Sending and receiving of telecommuni- cations message through appropriate channels.

Transmission line Set of conductors used to transfer signal energy from one location to another. A common application is the coaxial cable used to connect a station to an antenna.

Transmission loss Term used to denote a decrease in power during the transmission of energy from one point to another.

Transmitter Unit used for generating and amplifying an RF carrier signal, modulating the carrier signal with intelligence and then the

modulated signal into space. Trunk Multi-user one-way or two-way wireline used between communication switching equipment. 2-tone One of the early paging code formats utilizing two distinct tones transmitted in sequence.

Two-way Communications that occur between communications radio stations, each having a transmitter and receiver. The stations may be in fixed locations, mobile or portable, in any combination.

Uni-directional Antenna designed to radiate with antenna maximum strength or receive with maximum sensitivity in one direction and with minimum radiation or reception in the opposite direction.

User Individual operating a piece of equipment.

VHF Portion of the radio spectrum extending from 136 to 160 MHz (often called High band).

Visual alert Term used to describe a pager that signals with a blinking light.

Voice mail Sophisticated telephone voice messages that are recorded and translated into digital bits for storage and manipulation. Voice mail systems use specialized hardware and software and can be incorporated into a PBX or used as stand- alone systems.

Voice paging One-way communication of a message utilizing voice transmissions.

Voice retrieval Message system which stores verbal messages (from callers or operator) for automatic retrieval at customer's convenience. Can be used in conjunction with a paging terminal to alert customers of waiting messages.

Voice storage System designed to store voice paging messages on congested paging channels until the terminal can transmit.

Volt Basic unit of electrical potential. One volt is the force required to send one ampere of electrical current through a resistance of one ohm.

Watt Basic unit of power. Equal to the voltage (expressed in volts) multiplied by the current (expressed in amperes).

Waveform Graphical display of an electrical current as on an oscilloscope or similar piece of test equipment.

Wavelength Distance travelled by a wave in the time of one cycle. Electromagnetic waves include both light and radio waves and travel in space at approximately 300,000,000 metres per second. To determine the exact length of a wave (in metres), the above number is divided by the frequency (in hertz).