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66 Block
A terminal block used for the interconnection of telephone wiring. Also
known as a “punch down block” or “split block”.
“A” Battery
A term used to describe a filtered talk battery or supply. This is
generally used as the power source for the audio portion of an electronic
device. “A” battery may be substituted for “B” battery, but “B” battery
may never be substituted for “A” battery. Compare: B battery.
Air Plenum
Air space above drop ceiling tiles used for air return. Usually requires
special wiring or conduit to meet local fire code specifications.
Alert Tone
Alert tone which may precede a voice announcement from a paging zone.
Alert tones are primarily used in talkback paging systems in order to
discourage unannounced monitoring of zones.
All Call
A feature of a zone paging system which allows the user to a dial a
specific code and by doing so, access all of the speakers associated with
that system. If the zone paging system features a talkback capability, the
talkback signal is inhibited during all call access.
Ambient Noise
Background noise in an area.
Amphenol
A 50 connection terminal conductor connector commonly used for telephone
equipment and overhead paging systems.
Amplifier
An electronic device used to increase signal power or amplitude.
Antiblast Control
An automatic potentiometer. This device monitors the ambient noise level
and adjusts the audio output of paging speakers or horns accordingly when
inserted between the one-way page control and the audio input to the
speakers. (a.k.a. Automatic Volume Control)
Attenuation
Reduction in magnitude of any electrical parameter of a signal, on passing
along any transmission path.
Audio Frequency
Frequencies detected by the human ear, usually between 20 and 20,000Hz.
Automatic Gain
A device for holding the output volume of a audio source substantially
constant
Control despite variations in the input signal.
“B” Battery
A term used to signify a signal battery or supply. Generally a “B”
battery’s filtering is not as refined as an “A” battery’s, this source is
usually utilized to power the relays in an electronic device. Should not
be used for page control units in most cases. Compare: “A” Battery
Backbox
Speaker housing or enclosure designed to provide coverage for the rear of
a ceiling speaker. This coverage maybe required by local building codes
for air plenum type ceilings or may be used in other type ceilings to
protect the speaker from dust and debris accumulation.
Bandwidth
The range of signal frequencies that a circuit or network will respond to
or pass.
Battery Backup
An alternate power source that is used in the event of a loss of a
system’s primary power.
Battery Feed (BF)
A circuit utilized to provide talk battery as well as audio coupling in a
telephone system. It is generally provided by applying a potential
difference between two halves of a split coil (repeat coil).
BGM
Abbreviation for Background Music.
Bridge
An optional hardware device utilized for ceiling speaker support. It is
generally placed in a drop type ceiling so that the frame of the bridge
rest on the support grid system thereby alleviating any stress to the
ceiling tile itself.
Bridging Clips
Metallic clips used for connecting the two halves of a split punch down
block.
Butt Set
A self-contained test telephone primarily used for telephone
installation trouble-shooting. Used to listen to audio signals and provide
telephone access to paging systems.
Central Office (C.O.)
The switching equipment that provides local exchange telephone service for
a
given geographical area, designed by the first three digits of a telephone
number. The main distribution center for telephone service to a particular
area. In addition to basic telephone switching, C.O.s may also provide
Centrex or Essx service and direct inward dial (DID) service.
C.O. Line Position
A key system or PBX (PABX) C.O. line circuit which can be used to access
most Valcom Page Control Interface Units.
Centrally Amplified System
An old fashion type of public address system which utilizes central
amplifiers.
Centrex
Service provided through the C.O., which provides the end user with many
or all of the features of a PBX without the expense or upkeep of a private
switch. The service is purchased from the C.O. and requires no “on
premises” equipment.
Closed Loop
DC load applied across tip & ring which completes the circuit and allows
loop current to flow. This state indicates a request for service from the
control unit, station port or central office.
Combination Paging
A paging system in which a handsfree page control unit is used in
conjunction with both talkback and one-way speakers. (a.k.a. mixed paging)
Common Battery
A system of supplying direct current for the telephone set from the C.O>
(a.k.a. Talk Battery)
Contact Closure
A device, such as a relay or pushbutton, which provides a short circuit
upon activation. Closures are used to activate various features on page
controls as well as to activate certain controllers during page port
access.
Control Unit
With respect to paging systems, a control unit provides the interface
to the telephone system and may also provide various features.
Crosstalk
Undesired voice-band energy transfer from one circuit or conductor to
another (usually adjacent).
Daisy Chaining Cable
Wiring multiple devices on one continuous wire run. Compare: Home Run
Dial Tone
The tone that is heard by the caller when a multi-zone page control is
first accessed.
Distributed Amplified System
The modern way to integrate public address announcements with a telephone
system in which each speaker has a built-in amplifier and volume control,
(a.k.a. the Valcom System). Compare: Centrally Amplified System
Dry Contact Closure
A switchable set of contacts with no potential difference between them or
to any other reference point.
Dual-Tone Multi-Frequency
Use of two simultaneous voice band tones for signaling or dialing on a
telephone keypad. (DTMF)
Electric Strikeplate
An electro-mechanical door lock.
Equalizer (EQ)
A device that modifies an audio signal through the use of multiple
adjustable filters.
Extention Port
A port on a telephone system that is intended for connection to a system
telephone or station level paging adapters.
Federal Communications Commission (FCC)
A government agency that regulates and monitors the domestic use of the
electromagnetic spectrum for communications.
Feedback
The process of returning a fraction of the output energy of an energy
converting device to the input. The circuit that transmits the feedback
signal to the input is the beta circuit; the circuit containing the active
device, which generates the output signal, is the mu circuit.
Frequency
The rate in hertz (cycles per second) at which a signal pattern is
repeated.
Frequency Response
A measure of the effectiveness with which a circuit, device or system
transmits the different frequencies applied to it. The way in which an
electronic device (mic, amp or speaker) responds to signals having a
varying frequency. This is a measurement of how well an amplifier
reproduces and amplifies a specified audible range with equal amplitude or
intensity.
FXO
Foreign Exchange Office. (see also C.O. Line
Position, trunk)
FXS
Foreign Exchange Subscriber (see also Extension Port, Station Port)
Ground
An electrical connection to the earth or to a common conductor which is at
a reference potential that serves as a reference point for all other
potentials in the circuit.
Ground Start
With ground start signaling, a telephone immediately upon entering an
offhook state, requests service from the C.O. by applying a ground to the
ring lead of the tip and ring pair. The C.O. responds and indicates
preparation to receive digits, by placing a ground on the tip lead of the
tip and ring pair.
Group Call
The ability to page a specific combination of zones within a
multi-zone paging system.
Half-duplex
A circuit that carries information in both directions, but only in one
direction at a time.
Head End Equipment
The portion of a paging or telephone installation at which all of the
system components originate.
Hertz (Hz)
A unit of measurement used to indicate the frequency of sound or an
electrical waveform.
Home Run
The practice of providing a dedicated wire run to each speaker in a PA
system.
Compare: Daisy Chaining Cable
Impedance
A measure of the response of an electric circuit to an alternating
current. The current is opposed by the capacitance and inductance of the
circuit in addition to the resistance.
Inhibit
A feature on certain page controls which cancels or inhibits the paging
speaker audio whenever two phones are offhook on the page control’s tip
and ring. This feature is activated when each of the telephones provided
an “A lead” ground to 10k resistors which are common to the inhibit
terminal.
Intermediate Distribution Frame (IDF)
An extension of the main distribution frame (MDF). The IDF, usually at
some
distance from the MDF, is the location where subelements of the telephone
or paging system are distributed to a
particular area of an installation.
Loop Start
The usual method of signaling an offhook or line seizure, where one end
closes the loop and the resulting current flow is detected by a switch at
the other end. With loop start, the telephone upon entering an offhook
state, draws loop current from the C.O. thereby signaling that service is
being requested.
Loss
Attenuation of a signal from any cause.
Main Distribution Frame (MDF)
The location in a telephone or paging installation where all of the
elements
which comprise that system originate and/or interface with the public
telephone network.
Meet Me Page
A feature where following a general page, the paged party may dial a code
at an extension telephone and by doing so, secure a private talkpath to
the paging party and subsequently, free the page path for additional use.
Nightring
A feature which provide either by a telephone system, a page control or a
peripheral common audible ringing device. Nightringing provides a signal,
usually over the paging system, to indicate that a telephone line is in a
ringing state.
Non-polarized
Not sensitive to the applied signal’s polarity.
Off-hook
The condition that indicates the active state of a customer telephone
circuit.
Off Premise Extension (OPX)
A phone extension located in a different building from common equipment.
One-way Paging
Public address announcement with out the benefit of hearing response from
the paged area.
Override Tip & Ring
This feature is usually accessed through a separate tip and ring input and
allows any audio input from this tip and ring to override all other pages
in progress. Override tip and ring does not necessarily provide automatic
access to an all call.
Page Control Lead (PC)
An output terminal on select page control units that is connected
internally
through a N.O. relay to system ground. Whenever the page control is
accessed, the page control terminal is switched to ground potential. This
terminal is useful for providing ground to external relays.
PABX or PBX
A private (automatic) branch exchange is a telephone system that provides
telephone switching services within business or private establishment.
PBX’s provide 2 or 3 digit access from station to station as well as many
other features. The telephone terminals used with a PBX are generally of
the industry standard type.
Page Port
An audio output provided by a telephone system. Usually the page port is
accessed by dialing a code or selecting a dedicated line key.
Parallel Connection
Connection of system elements such that like connection points are common.
Phantom Zone
This term is used to describe a “non-background music” zone output on a
single zone page control. Single zone page controls, which provide a
phantom zone, will always have dual speaker outputs, one with BGM and one
without BGM.
Pinout
The physical pattern of connection points for a device.
Plain Old Telephone Service (POTS
Single line residential rotary dial service. Quite often a 500 (rotary
desk) or
2500 (touch tone desk) telephone may be referred to as a “POTS
telephone”.
Potentiometer
A variable resistor. A movable sliding contact is used to vary the
potentiometer’s resistance.
Relay
An electromechanical device comprised of a coil and various sets of
contacts (determined by the relay selected). When a voltage is applied to
the coil, a magnetic field is induced around the coil. The magnetic field
attracts metallic, movable contacts and creates either a closed contact or
an open contact or various combinations.
Repeat Alert Tone
A tone heard through a talkback speaker every 15 seconds to prevent
eavesdropping.
Ring
The alerting signal to the subscriber or terminal equipment; the name of
the one conductor of a telephone wire pair, designated by R.
Ring Voltage
Voltage that is applied to a telephone or telephone system in order to
signal an incoming telephone call.
Ringback Tone (RBT)
In telephony, it is a progress tone heard by the calling party, which
indicates that signaling (ringing) is being provided to the called party.
Ringer
A device that produces audible signaling in response to ring voltage or
contact closure.
RTHF
Rotary Tone Handsfree
RTVA
Rotary Tone Voice Announce
Series Connection
Circuit elements that are connected so that current flows through each of
them.
Side Tone
The portion of the talker’s voice which is fed back to his receiver.
Signal Battery
See B Battery.
Sound Reinforcement
Amplification of a line of site speaker’s voice.
Stand Alone System
A system that does not require the support of subsequent system(s).
Splash Tone
A tone that immediately precedes a voice announcement on handsfree
talkback systems (prevents eavesdropping).
Station Level
Access Indicates that the paging equipment will be accessed via an
incoming phone line or station port rather than through a KSU or PBX page
port or trunk port. Users must dial an extension number or telephone
number in order to execute a page.
Station Port
An output on a KSU or a PBX where the actual telephone terminal is
connected.
Strikeplate
See Electric Strikeplate.
Subscriber
The telephone service customer.
Switch
A generic term for a KSU or PBX.
Talk Battery
See A Battery.
Talkback
A type of paging system in which individuals in the paged area can respond
through the paging speakers of horns.
Time Clock Tone
A single tone broadcast through the paging system when a time clock
controlled dry contact closure is applied to an appropriate signaling
device.
Tip
One conductor of a telephone wire pair, designated by T; usually the more
positive of the two.
Tip & Ring
The terms used to identify single pair telephone station wiring. The tip
conductor usually has a positive potential with respect to the ring
conductor.
Trunk
A transmission channel connecting two switching machines.
Trunk Port
The point of connection on a telephone system where the central office
lines or trunk lines, are usually connected.
UPS
Uninterruptible Power Supply.
Valcom Power Unit (VPU)
One Valcom power unit is equal to and defined as, 50mA @ 24VDC. Valcom
power units were devised in order to aid in the determination of total
system power required when configuring a Valcom paging system.
Voice-grade Line
A local loop or trunk, having a bandpass of approximately 300 – 3,000Hz.
Voice Operated Switching (VOX)
Provides the ability to activate a device simply by the presence of a
specific
level of audio signal.
Voltage
A measure of the electrical force that causes current flow in a circuit.
VSP
Valcom System Practice. Term used for a Valcom Installation Manual.
XLR Connector
A connector usually utilized for the connection of a microphone to its
associated cable. The pin count of an XLR connector may vary from three to
seven pins.
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