| A | B | C | D | E | F | G | H | I |
| J | K | L | M | N | O | P | Q | R |
| S | T | U | V | W | X | Y | Z |
ADC
Analogue-to-Digital Converter
An electronic circuit that converts discrete analogue signals to digital levels.
[more]
ADPCM
Adaptive Differential Pulse Code Modulation
A form of pulse code modulation (PCM) that produces a digital signal with a lower bit rate than standard PCM.
[more]
ADSI
Analogue Display Services Interface
A signalling protocol used by many screen-based analogue, POTS-compatible telephones to work with optional
services.
[more]
ADSL
Asymmetric Digital Subscriber Line
A technology for transmitting digital information at a high bandwidth and speed on existing telephone lines.
[more]
AGC
Automatic Gain Control
An electronic circuit that keeps a receiver within in its linear operating range by measuring the overall strength of
the signal and automatically adjusting the gain of the receiver to maintain a constant level of output.
[more]
AIS
Automatic Identification System
A Radio based system for tracking (marine) vessel's position and other key information,
such as speed and heading.
[more]
Knowledge Base White Paper introducing Marine AIS
AM
Amplitude Modulation
A radio modulation method whereby a high frequency (RF) carrier-frequency is modulated by a lower baseband signal (AF)
- the modulating signal.
[more]
AMPS/NAMPS
Advanted Mobile Phone Service
A cellular communications system used in the United States.
[more]
ANI
Automatic Number Identification
Identification, at the receiver, of the transmitting party by a pre-assigned number.
[more]
ANSI
American National Standards Institute
A voluntary organisation in the United States that co-ordinates standards.
[more]
API
Application Programming Interface
The interface that a computer system, library or application provides/requires in order to allow requests for services
to be made of it by other computer programs, and/or to allow data to be exchanged between them.
[more]
ARDIS
Advanced Radio Data Integrated System
A public wireless data service. An FM radio data system that operates at 9.6kbps and 19.2kbps.
Trademarked by Motorola.
[more]
Async Tx
Asynchronous Transmission
A mode of data transmission in which each bit is not in sync -in respect of frequency or timing.
[more]
ATM
Asynchronous Transfer Mode
A network technology based on transferring data in cells or packets of a fixed size.
[more]
Bandwidth
The range of frequencies within which an electronic device efficiently can operate (transmit or receive).
[more]
Baseband
The band of frequencies which is modulated onto a carrier or sub-carrier in a wire or transmission medium to
form the transmitted signal.
[more]
Baud
A unit of data signalling speed in events per second. This may not always be in bits per second.
[more]
BCD
The Binary-Coded-Decimal Number System.
[more]
BER
Bit Error Rate: A ratio of the number of transmitted bits that are incorrectly received,
to the number that are correctly received.
[more]
Bit Rate
The speed at which bits are transmitted over a data channel, given in bits-per-second (bps).
[more]
BOC
Bell Operating Companies:
[BOC Introduction]
BPS
Bits-Per-Second: The speed at which 'bits' are transmitted over a data channel. The bit rate.
Bit Rate
The speed at which bits are transmitted over a data channel, given in bits-per-second (bps).
[more]
BSC
Basic Spacing Between Centers. To specify IC package mechanical dimensions.
This is a theoretical true-postion dimension and has no tolerance.
CML Package Diagrams
CAS
Dual Tone CPE Alerting Signal as defined in Bellcore spec. SR-TSV-002476.
[more]
CATV
"Cable Television": (originally called "community antenna television," now often called "community access television").
[more]
C-BUS
CML’s serial bus and control system used to communicate digital information between a µP or µC and peripheral ICs.
[more]
CCIR
International Radio Consultative Committee, a subsidiary organization of the International Telegraphic Union dealing in radio standards.
A predecessor organization of the [ITU].
CCITT
Comité Consultatif International Téléphonique et Télégraphique, an organization
that sets international communications standards. CCITT, now known as ITU.
CDMA
A form of multiplexing and a method of multiple access that encodes data with a special code
associated with each channel.
[more]
CDPD
Cellular Digital Packet Data: An industry standard for data transmission over cellular networks.
[more]
Cartesian Feedback Loop
A method of maintaining a linear transmitter output spectrum.
[more]
CID
Caller Identification or Calling Line Identifier (Type 1) (Bellcore).
[more]
CLI
Caller Identification or Calling Line Identifier (Type 1) (Bellcore).
[more]
CIDCW
Caller Identification on Call Waiting or Calling Line Identifier on Call Waiting (Type 2)
[more]
CLIP
Calling Line Identity Presentation (BT)
[more]
CMOS
Complementary Metal-Oxide Semiconductor - and integrated semiconductor manufacturing process.
C-MSG
‘C-Message Weighting’: Represents frequency response of a typical United States telephone wireline.
Codec
A single device or function comprising both Encoder and Decoder sections.
In CML documents, functions using encode/decode operations such as: Selcall, DTMF and Sub-audio are
sometimes refered to as 'codecs'.
Compandor
Compressor-Expander, a circuit that compresses the dynamic range of a (Tx) signal and
expands it (Rx) almost back to its original form on the output.
Concatenation
Combining multiple data packets or frames in a contiguous series.
CPE
Customer Premises Equipment - i.e. A telephone set, a fax machine, a modem.
CPFSK
Continuous Phase Frequency Shift Keying: A commonly-used variation of frequency-shift keying (FSK).
CPM
Continuous Phase Modulation: The carrier phase is modulated in a continuous manner.
CRC
Cyclic Redundancy Check: a type of error detecting code.
A method to detect and correct errors in data signals by adding bits derived from a data-block or
string of bits to the block.
[more]
Crosstalk
Undesired crossover of voice or audio signals from one circuit to another.
CSTDMA
Carrier Sense TDMA: The channel access scheme used by AIS Class B.
[more]
CTCSS
Continuous Tone Controlled Squelch System. Continuously superimposes any one of about 50 low-pitch audio tones
onto the transmitted radio signal. CTCSS is often called PL tone (for Private Line, a trademark of Motorola), or simply tone squelch
[more]
CVSD
Continuously Variable Slope Delta Modulation: A method by which a voice signal is digitized for
transmission, and then changed back to an analogue voice signal during reception.
[more]
DAA
Data Access Arrangement: A special interface for connecting modem ICs to a telephone line.
CML has available, for free download,
several DAA designs for its wireline telecom modems.
[more]
DAC
Digital-to-Analogue Converter: For converting
a digital code to an analogue signal (current, voltage or electric charge).
[more]
dBm
Signal Level Measurement; Decibels above or below 1 milli-watt
DC
Direct Current: Often used to refer to the static or unchanging part of a signal.
DCA
Digitally Controlled Amplifier: FX/MX019 and FX/MX029 are IC examples of such functions.
DCE
Data Communications Equipment or Data Circuit-Terminating Equipment:
This equipment functions to establish and maintain a connection, and provides signal conversion between a
terminal and data or telephone line.
DCS/CDCSS
Digital Coded Squelch: Similar to CTCSS in function but utilizes digital tones to control the same operations.
[more]
DPCM
Differential Pulse Code Modulation: A digital representation of an analogue signal where the magnitude of the
signal is sampled regularly at uniform intervals, then quantized to a series of symbols in a digital code.
DPM
Differential Phase Modulation:
dPMR/ Digital PMR/LMR
Digital Private Mobile Radio:
CML in dPMR:
[A Low-Cost Digital Successor to PMR446]
CML's dPMR products:
[dPMR - A Digital PMR/LMR Platform Processor
IC - CMX7141]
DQPSK
Differential Quadrature Phase Shift Keying: A modulation technique in which the carrier can assume one of four phases,
each change of phase, or symbol, representing 2bits. The bit combinations being 00, 01, 11 and 10.
Consequently the data stream can carry 2bits at a time.
[more]
DSC
Digital Selective Calling: An early maritime communication system.
[more]
DSP
Digital Signal Processing: Changing or analysing information which is measured
as discrete sequences of numbers.
DT-AS
Dual Tone Alerting Signal: (BT CLIP alert tone).
DTE
Data Terminating Equipment: For wireline telephone systems.
DTMF
Dual Tone Multi-Frequency: Generally, a telephone signalling system employing
four tones from a low group, and three or four tones from a high group, comprising
twelve to sixteen different unique tone pairs.
[more]
DTS
Digital Terminal Systems: For wireline telephone systems.
DVSR
Data/Voice Storage and Retrieval: Trademarked by MX-COM (CML USA) as Radio MailVoxTM.
DWDM
Dense Wavelength Division Multiplexing: A fibre-optic transmission technique that
employs light wavelengths to transmit data, parallel-by-bit or serial-by-character.
ECPA
Electronic Communications Privacy Act (1986): This amendment to Section 2510 of title 18,
United States Code, establishes the illegality of intercepting protected (i.e. scrambled) communications.
EIA
Electronics Industry Association: A United States Manufacturers’ group which, as part of its function,
sets and publishes electronics standards.
ETSI
European Telecommunications Standards Institute. The European
Telecommunications Standards Institute (ETSI) is an
independent, non-profit organization, whose mission is to produce telecommunications standards for today
and for the future. CML is currently a full member.
Eye Pattern/Eye Diagram
An oscilloscope display of the detector voltage waveform in a (GMSK) modem.
The openness of the ‘eye’ gives a representation of the bit error rate (the more open, the less distortion).
Sampling the "eye" at its center provides proper signal detection with the highest signal-to-noise ratio possible.
[more]
FCS
Frame Check Sequence: The term referring to the extra characters added to a data frame for
detecting and correcting errors.
FDMA
Frequency Division Multiple Access: An access technology that is used by radio systems to share the radio spectrum.
In FDMA the given Radio Frequency (RF) bandwidth is divided into smaller frequency bands called subdivisions.
Each subdivision has its own carrier frequency. Sharing is done by allocating users with different carrier frequencies
of the radio spectrum.
FEC
Forward Error Correction: A method of obtaining error control in data transmission in which the source (transmitter)
adds 'check bits' to the outgoing data stream; the destination (receiver) recognizes only the portion of the data
that contains no
apparent errors.
Because FEC does not require handshaking between the source and the destination,
it can be used for the broadcasting of data to many destinations simultaneously from a single source.
FFSK
Fast Frequency Shift Keying: Also known as Minimum Shift Keying(MSK).
A form of frequency modulation.
FIFO
First In - First Out: A queue-based data buffer where data is output in the same order as
it arrives. Also known as an ‘elastic buffer’.
FirmASIC®
CML’s proprietary FirmASIC® component technology reduces cost, time to market and development
risk, with increased flexibility for the designer and end application.
FirmASIC® combines Analogue, Digital, Firmware and Memory technologies in a single silicon
platform that can be focused to deliver the right feature mix, performance and price for a target application family.
FSK
Frequency Shift Keying: A form of frequency modulation used to transmit two states of a signal each as
separate frequencies. FSK is characterised by a frequency spacing of 1.
FTP
File Transfer Protocol: A standard Internet protocol employed to exchange files between computers on the Internet.
Like the Hypertext Transfer Protocol (HTTP), FTP is an application protocol that uses the Internet's
TCP/IP protocols. FTP is commonly used to transfer Web page files from their creator to
the computer that acts as their server to the Internet.
Full-Duplex
Simultaneous (wireless or wireline) two-way communication:
Fixed Wireless Phone (FWP)
A wireless communications system used to extend the range/capacity of a wireline communications system in areas where
there are no copper telecommunication cables or it is uneconomical or physically difficult to install them.
[more]
Fixed Wireless Terminal (FWT)
A wireless communications system used to extend the range/capacity of a wireline communications system in areas where
there are no copper telecommunication cables or it is uneconomical or physically difficult to install them.
[more]
Galileo
A radio satellite navigation system developed by the European Union and the European Space Agency:
Gaussian Filter
A filter having the symmetrical bell shape of a (normal distribution) Gaussian curve.
[more]
GFSK
Gaussian Filtered Frequency Shift Keying: An FSK modulation scheme with a Gausian filtered output signal.
GLONASS
Global Orbiting Navigation Satellite System: A satellite navigation system developed by the
Commonwealth of Independent States (former Soviet republics).
GMSK
Gaussian Minimum Shift Keying: A type of FSK that uses pre-modulation Gaussian filtering to achieve high data rates in an
FM communications channel bandwidth.
[more]
GNSS
Global Navigation Satellite System: A generic term for the GPS, GLONASS and Galileo satellite navigation systems.
GPS
Global Positioning System or Global Positioning by Satellite.
GSTN
General Switched Telephone Network.
Half Duplex
Communications in which both transmit and receive operations occur, but not at the same time.
HDLC
High-level Data Link Control: A synchronous data-link protocol. A bit-oriented synchronous data link layer protocol
developed by the International Organization for Standardization (ISO).
[more]
HSC
Hexadecimal Sequential Coding: An in-band tone signalling protocol comprising 16 tone states.
[more]
HSC Tonesets
Hook Switch
The switch in a telephone (type-product) which is operated when the handset is placed on (or off) the cradle.
IC
Integrated Circuit: CML designs, manufactures and markets, low-power application specific standard product
integrated circuits for communications applications worldwide.
IEEE
The Institute of Electrical and Electronic Engineers:
One of the functions of this association of technical engineers is to publish standards defining technical terms.
[IEEE website]
IMO
International Maritime Organisation: The United Nations' specialized agency responsible for improving maritime
safety and preventing pollution from ships.
ISDN
Integrated Services Digital Network: A circuit-switched telephone network system, designed to allow digital
transmission of voice and data over ordinary telephone copper wires, resulting in better quality and
higher speeds than that available with the Public Switched Telephone Network (PSTN) system.
ITU-T
International Telegraphic Union - Telecommunications: (includes the CCITT and CCIR) is an
international telecommunications standards agency.
Jitter
Small, abrupt, spurious variations in a waveform due to time, amplitude, frequency or phase.
LMR
Land Mobile Radio system. Also refered-to as Public Mobile Radio (PMR) and/or Public Land Mobile Radio (PLMR).
LSI
Large Scale Integration: Integrated circuit systems with at least a thousand gates.
LTE
Telephone-Line Terminating Equipment.
LTR
Logic Trunked Radio: An EF Johnson trademarked radio trunking system.
LTR is a method of channel management that gives all users of the system automatic access to all channels.
Mobitex
A data transmission protocol developed by Swedish Telecom (from 2004 administered by Mobitex Technology AB).
Mobitex is an OSI based open standard, national public access wireless data network; a packet-switched, narrowband,
data-only technology mainly for short burst data. The modulation scheme used is GMSK.
Modem
(Data) MODulator/DEModulator: This is a type of DCE that connects data terminal equipment (radio, wireline, optic)
to a communications line/channel. It converts data to and from the signal form needed for the communication channel.
Modulation
The process of modulation of a carrier or signal for transmission, also the result of this process.
The addition of information (or the signal) to an electronic or optical signal carrier.
Monolithic
Constructed from a single crystal or piece of material.
MSK
Minimum Shift Keying: Continuous phase FSK modulation (also called FFSK) used to transmit two states of a
signal as two separate frequencies using coherent detection and a frequency spacing of 0.5.
Multiplexing
Combining multiple signals for transmission as a group over a single transmission facility.
NMEA
National Maritime Electronics Association: The international organisation which is dedicated to the
education and advancement of the marine electronics industries.
NMT
Nordic Mobile Telephone: A Cellular communication system used primarily in Europe.
NRZ
Non Return to Zero: a simple data coding method where only two dc levels are valid using a high level to represent
a one and a low level to represent a zero.
The opposite level-to-bit mapping may also be used. Each bit is represented by one clock
period at the appropriate DC level.
NRZI
Non Return to Zero Inverted: A binary data coding scheme where 1s cause no change in a transmitted signal level,
and 0s cause a change.
NT
Network Terminator: A device within an ISDN system that accepts a two-wire signal from the phone company and converts
it to a four-wire signal that sends and receives to and from devices within the home or business.
On-Hook
The condition when the telephone customer premises equipment (CPE) is not being used - i.e.
the telephone handset is on the cradle.
Off-Hook
The condition when the telephone customer premises equipment (CPE) is in use - i.e. the telephone handset is
removed from the cradle, releasing the hook switch.
OSI
The Open Systems Interconnection Reference Model (OSI Model or OSI Reference Model)
is a layered abstract description for communications and computer network protocol design.
Developed by the European-dominated International Organization for Standardization
(ISO).
PABX
Private Automatic Branch Exchange. An automatic telephone exchange that serves a particular business or organisation.
PA
Power Amplifier. A component or system.
PAMR
Public Access Mobile Radio: A commercial service using trunking techniques in which multiple groups of
users can set up their own closed systems within a shared public network.
PBX
Private Branch Exchange: A manual telephone exchange that serves a particular business or organisation.
PCM
Pulse Code Modulation: A process by which an analogue signal is sampled and converted to a binary code for
transmission.
[more]
PCMCIA (PC Card)
Personal Computer Memory Card International Association: This association defines and promotes an interchangeable
standard for PC memory and expansion cards.
The PCMCIA standard applies to 68-pin I/O or interchange type cards.
PCMCIA (PC Card)
Personal Computer Memory Card International Association: This
association defines and promotes an interchangeable standard for PC memory and expansion cards.
The PCMCIA standard applies to 68-pin I/O or interchange type cards.
PER
Packet Error Rate: A packet data measurement.
The ratio, in percent, of the number of data packets not successfully received by a receiving access terminal (AT)
to the number of data packets sent to that terminal.
PDA
Personal Digital Assistant: A handheld (pocket or palmtop) computer that provides functions like a notepad, a messagepad
or a personal organiser.
PDAs often include data and voice transmission capabilities.
PMR
Public Mobile Radio system: Also refered-to as Land Mobile Radio (LMR) and/or Public Land Mobile Radio (PLMR).
PL
Private Line: A Motorola trademarked name for CTCSS.
POTS
Plain Old Telephone System: The original basic analogue telephone system (PSTN).
PRBS
Pseudo-Random Bit Sequence: An apparently random stream of bits typically generated by
a linear-feedback shift register.
PSK
Phase Shift Keying: A form of phase modulation requiring coherent detection.
The most straightforward type of PSK shifts the carrier by 0° or 180°.
Psophometric
A weighting curve used to represent the energy density of speech.
PTM/PTL
‘Push To Monitor’ or ‘Push To Listen’:
A control function used in two-way radios to allow channel monitoring.
PSTN
Public Switched Telephone Network: A collection of interconnected voice-oriented public telephone networks,
both commercial and government-owned. It's also referred to as the Plain Old Telephone System (POTS).
Pvt Squelch
Trademarked combination of CTCSS and voice inversion to provide over-air voice privacy.
(MX·COM (CML (USA)).
QAM
Quadrature Amplitude Modulation: A hybrid amplitude/phase modulation technique that allows the transmission of
four bits of information during a signaling interval, and requires less bandwidth than normal amplitude or
phase modulation techniques.
[more]
QPSK
Quadrature Phase Shift Keying:
[more]
Quick Call II
A Motorola trademarked 2-Tone sequential signaling format comprising 80 tones arranged in eight tone groups.
R2000
A trunked communication system used in France.
RALCWI
Robust Advanced Low Complexity Waveform Interpolation
A low bit-rate algorithm for vocoder implementation; licenced to Spirit DSP.
[more]
RAM
Random Access Memory: A type of data store used in computers that allows the stored data to be
accessed in any order.
Read/Write memory.
RD-LAP
Radio Data-Link Application Protocol: An FM radio data protocol that operates at 9.6kbps and 19.2kbps.
Trademarked by Motorola.
[more]
Repeater
A device used as an intermediate point in a communications system to receive and
retransmit signals, often for the purpose of extending (radio) signal range.
RF
Radio Frequency. Generally accepted to range from about 3 kilohertz to about 300,000 megahertz.
RSSI
Received Signal Strength Indicator: A signal or a circuit to measure/indicate the strength of an incoming signal
Rx
Receive or Receiver:
SAT
Supervisory Audio Tone: used in cellular telephone systems.
SCWID
Spontaneous Call Waiting IDentification: An enhanced telephony call waiting feature. An alert signal is
provided to supply identifying information related to a third party wishing to join with someone already engaged
in a conversation with another person.
Selective Calling
A method of signalling over a radio system using a sequence of audio tones,
usually before the voice signal (squelch) is enabled.
[more]
SiGate
Silicon Gate: A CMOS process used in manufacturing ICs that is smaller and more modern than metal gate.
Simplex
A circuit which can communicate information in a channel in one direction only.
SINAD
A ratio of the total output power to the power of noise plus distortion only:
SINAD = signal + noise + distortion ÷ noise + distortion
SIT
Special Information Tones in a telephone system; usually a series of audio tones.
SMD/SMT
Surface Mount Device / Surface Mount Technology. techology used in the encapsulation of integrated circuits.
SPI
Serial Peripheral Interface: A common inter-chip serial communications interface. Generally compatible with CML's
C-BUS serial interface.
SOTDMA
Self Organised TDMA: The channel access scheme used by AIS Class A.
SS
Spread Spectrum: The spreading of a signal over a wider bandwidth than the minimum required for transmission
of the information.
Synchronous Transmission
A type of data transmission in which the sending and receiving ends operate continuously at
the same frequency and in phase.
TACS/ETACS
Total Access Communications Systems is a cellular system used in the United Kingdom.
ETACS is used in Europe and Japan.
Talk-off
Condition where dual tone alerting signals are falsely detected because of imitation by speech or music.
Talk-down
Condition where dual-tone alerting signals are missed due to interference from speech or music.
TCP/IP
Temperature Compensated Crystal Oscillator.
TDMA
Time Division Multiple Access, a technique for sharing access to a radio channel by dividing it into
different time slots.
Tx
Transmit or Transmitter.
TE
Terminal Equipment. European equivalent for Customer Premises Equipment (CPE)
TETRA
TErrestrial Trunked RAdio: An open digital standard for radio communications defined by the European Standards
Institute (ETSI).
[more]
TCXO
Temperature Compensated Crystal Oscillator.
TIA
Telecommunications Industry Association: A United States
Manufacturer’s group which, as part of its function, sets and publishes telecommunications standards.
Type 99
A General Electric trademarked 2-Tone sequential format comprising 30 tones
Trunking
A communication system sharing communication channels.
UART
Universal Asynchronous Receiver/Transmitter. Takes bytes of data and transmits the individual bits in a sequential
fashion. At the destination, a second UART re-assembles the bits into complete bytes.
USART
Universal Synchronous-Asynchronous Receiver/Transmitter. Handles both serial synchronous
data and asynchronous data, adding start and stop bits and performing parity checks as required.
UTC
Universal Time (Coordinated), the official measure of time in the world.
Kept in synchronisation with the earth’s rotation by the introduction of occasional leap seconds.
VCO
Voltage Controlled Oscillator.
VLSI
Very Large Scale Integration: Integrated circuit systems with at least ten-thousand transistor-based circuits.
VMWI
Visual (or Voice) Message Waiting Indicator.
An FSK message sent without power ringing to a CPE to activate an LED or other visual indicator on the
receipt of voice mail at the local phone company.
[more]
VOGAD
Voice Operated Gain Adjusting Device: Similar in concept to an AGC (Automatic Gain Controlled) amplifier, used
to ensure full modulation of all speech levels.
VoIP
Voice Over IP: Any telephony application that can be enabled across a packet-switched data network via the
Internet Protocol.
VOX
Voice Operated Switching.
VSB
Variable Split Band: A type of high-level analogue voiceband scrambling which splits and inverts
the voice band frequencies.
VHF
Very High Frequency: ITU band 8, generally accepted as 30 to 300 MHz, that includes the maritime mobile band.
VQFN
Very thin profile Quad Flat No lead, an IC package type.
Wireless Local Loop (WLL)
A wireless communications system used to extend the range/capacity of a wireline communications system in areas where
there are no copper telecommunication cables or it is uneconomical or physically difficult to install them.
[more]
XTCSS Signalling
A squelch signalling format for radio systems, using both sub-audio (CTCSS) and in-band (XTC) signalling
concurrently.
[more]