communication & signal

7/23/2019 Communication & Signal

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COMMUNIC TIONS ND

SIGN L SYSTEMS



3. Time Equipment

clock and program equipment

1.1.2 Parts of the

Communication & Signal

Systems

1. Detectors

2. Control Unit or Panel

3. Alarm Devices

4. Wiring or Circuitry

1.0 COMMUNICATIONS & SIGNAL SYSTEMS

1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and

Intercommunications Systems

1.1 General

1.1.1 Types of

Communication & SignalSystems

1. Surveillance and Signal

Equipment

Fire, smoke and intruder detection

and alarm systems

In general, all signal systems require

a surveillance system to process

information including transmitting it

and a means of indicating the signal,

either audibly, visually or

permanently on “hard copy”.

2. Audio and Visual

Communication Equipment

telephone, intercom, public TV and

closed circuit television (CCTV)




1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


1.2 Fire Alarm System

1.2.1 Types of Fire Alarm

Systems

1. Automatic System

uses detectors to trigger the alarm

system.

2. Manual System

uses visual detection and the alarm

is triggered by hand.

a) Non-Coded Manual Stations

the station locations are not

identifiable at the control panel when

it is manually triggered. Anannunciation panel, however, can be

added to the system, to convert

each station as a non-coded

indicating zone. Beyond 10 stations,

coding should be considered.

b) Coded Manual Stations

Each manual station is coded and

this code is received at the control

panel, processed and transmitted

audibly on the system gongs. Thecode usually comprises of 3 to 4

digits; the first number may identify

the building number, the second the

building floor and the third the

individual station.




1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


1.2.2 Detectors

1. Temperature Detector

the most common is the

Temperature Detector called the

“thermostat”

a) Fixed Temperature Unit

triggers a set of contacts when a

present temperature is reached.

This unit is available in a one-timenon-renewable design that uses a

low melting alloy fusible plug.

b) Rate-of-Rise Unit

activates when the rate of ambient

temperature differential exceeds a

predetermined amount. This unit

may be combined with the fixedtemperature unit in a single housing

such as in the case of an automatic

resetting unit.

Detectors are rated by temperatureand coverage. For example in

ordinary rooms, detectors are rated

at 135 deg F per 200 sqft. For

kitchens, attics and basements

where ambient temperature is

higher, units are rated at 190 deg to

200 deg F.




1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


projector sensor

3. Ionization Detector

These detectors operate by

detecting ionized particles in the air.

They do not detect fires producing

heavy smoke but few particles such

as alcohol and plastic fires.

Photoelectric and Ionization

Detectors are classed respectively

as early warning smoke and firedetection devices.

4. Flame Detectors

These detectors are of two types;

the Infrared (IR) and Ultraviolet (UV)

Detectors. Applications are generally

industrial and are highly sensitive.

2. Photoelectric Detector

These detectors react to the

obscuration of a light beam by

smoke. They are best applied where

fires produce considerable quantitiesof smoke and gas, such as those

caused by slow burning plastics.




1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


1.2.3 Control Unit or Panel

the function of the control panel is to

energize the audible devices (bells,

buzzers, gongs) upon receipt of a

signal from the detector. Other

functions include shut-off of oil and

gas lines, shut off of attic fans to

prevent fire spread, and turning off

of lights. Most units are serviced

with an emergency standby battery.

The typical control functions in the

Fire Alarm Panel are:

1. Non-Coded Systems

These are continuous ringing

evacuation type alarm devices,manual or automatic, which can be

zoned and identifiable by means of

an annunciator.



3. Zone Coded Systems

Manual stations are grouped bycircuit into zones which transmits to

the panel and ring the zone’s code

on the single stroke gong or chimes,

thus immediately identifying the

station.


1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


2. Master Coded Systems

This system is also called the

common coded or fixed coded

system and generates 4 rounds of

code. When the code is set to ringthe bells at 108 strokes per minute,

the alarm is known a “march time”

because of the rhythmic cadence.

This alarm best applies in the rapid

evacuation of a building and is

frequently used in schools.



5. Selective Coded Systems

This is a fully coded system in whichall manual devices are coded and all

automatic devices are arranged to

trip code transmitters at the panel.

6. Pre-signal System

When it is desired to alert only key

personnel, a system called pre-signaling is used, where it is also

selectively coded. The personnel

can immediately investigate and turn

on the general alarm manually.


1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


4. Dual Coded Systems

This system is a combination of thenon-coded and the zone coded

systems. When an alarm device

operates, it initiates two different

functions – an identifying coded

alarm located in the maintenance

office and a continuous ringing

evacuation alarm for the wholebuilding.



1.2.5 Circuit Design

A system which is usually de-

energized and functions only when

activated is called an open circuit

system. An open circuit system

which integrates a trouble light to

indicate a malfunction is called a“supervised system”.


1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


1.2.4 Alarm Devices

usually audible such as, bells,

buzzers, gongs and horns. Most

common is the a-c vibrating bell and

a weatherproof external bell to alert

neighbors and passersby



1.4 Sprinkler Alarm

Water flow switches are installed to

monitor the flow of water in a

sprinkler head and when triggered

will trip a coded transmitter, setting

off a sprinkler code to show up on a

sprinkler annunciator board (called a

sprinkler alarm panel).


1.3 Intrusion Burglar)

Alarm System

Intrusion detection is similar to thefire detection system, except that

instead of thermal detection, devices

such as metallic tape and micro-

and magnetic- switches are used to

detect door and window motion and

glass breakage. An eye or a laser

light beam may also be used todetect movement once blocked.

1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and




2. Personnel Entry Control

by use of a card reader

a) The first level is by simple

insertion of a card by the holder toan electric device which grants entry

when a card is inserted into it for

identification.


1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


1.5 Industrial Building

Security System

1. Door and Exit ControlsThese cover electrified security door

hardware that triggers an alarm

when a door is opened without

authorization, such as, in exterior

doors and doors to restricted areas.



3. Watchmen’s Tour Equipment

this type of station allows a guard to

call in through an intercom and

permits a general alarm to ring

through operation of a key.


1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


b) The second level requires the

encoding of a three-digit number

simultaneously with the insertion of

a card. This bars the entry of

unauthorized card holders.

c) The third level involves an

attendant who compares card data

through a computer screen with the

person’s appearance providing a

further check.



1.7 Sound Amplifying

Systems or Public

Address Systems

Consists of the following:

1. Microphone

to pick up the sound and convert it

to an alternative electric current.

2. Amplifiers

amplifies and controls the current.

3. Loudspeaker

converts amplified electric current

back into sound much louder than

the original sound entering themicrophone.


1.6 Television Antenna

System

The system functions by amplifyingthe signal received by the TV

antenna and by means of a special

cable, distribute these amplified

signals into the various wall outlets.

A system with two or more outlets

generally needs a booster amplifier.

1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and





1. The intercom

system comprises

one or more master

stations

(administrative) and

several remotestations (staff), one of

which monitors the

front door. The master

station allows

selective calling while

remote stations

operating through the

masters are non-

selective.

1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


1.8 Telephone and

Intercommunications

Systems

CO C O S S G S S S




1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


• direct internal and external

dialing

• consultation hold ( ability to hold

an outside call while making an

inside call)

• conference call capability for

internal and external units• call transfer and camp-on feature

• automatic call back

• call forwarding

• distinctive ringing for different

functions

• paging, executive priority,

dictation access, personnel

location and other options

2. The Private Automatic

Branch Exchange or PABX is

based on solid-state technology,

thus the entire system can handle

up to 500 lines and trunks, 4operator consoles, and over 140

simultaneous conversations plus

full intercom facilities, all

occupying a cabinet 0.60 M x

0.70M x 1.8 M. The operational

features of this system include:

COMMUNICATIONS SIGNAL SYSTEMS



2. Protectorgenerally required in residential

telephone lines to protect against

lightning. When a conduit entrance

and an interior conduit system are tobe installed, it is desirable to provide a

cabinet to accommodate the protector

usually a metal box of same type used

in electrical work. Located as close as

possible to the point of entrance, one

protector is required for each pair of

telephone wires entering the building

3. Main Terminal Cabinet or RoomThe serviced wires end at the main

terminal cabinet. Small sized wall type

terminals are mounted to metal

cabinets attached to or recessed in

walls or columns. Large sizes of walltype terminals and frame type

terminals (terminals mounted in frames

accessible from both sides) should be

located in rooms which are intended

for the purpose and constructed of fire

resisting materials.


1.8.1 Elements of the

Telephone Installation

1. Service Entrancethe service connection from a pole

or other outside terminal location to

a point of entrance into the building

The service entrance may be:

a) Overhead with overheadexposed wires.

b) Underground with concealed

underground wires in conduits. The

service conduit is usually of rigid iron

same for electrical works. Minimum

size of service conduit is ½” round.

There should be a clearance of not

less than 6” between telephone

service conduit and the electric

conduit.

1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and






1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


Protector

OVERHEAD

Protector

UNDERGROUND




Risers whether conduits or shafts,

require central locations in relation

to floor area served. Buildings with

large floor areas or with floors so

planned so as to result in two ormore distinct areas will probably

need a separate riser for each area.

5. Splicing Cabinets or Splicing

Closets

permit the riser cables in the risershaft or conduit to be spliced or

interconnected to the cables or

telephone wires to the various

floors.

6. Floor Conduits

connects the splicing closets orcabinets into the distribution terminal

cabinets and to floor ducts, wall

outlets, etc.


4. Vertical Riser Conduits or Riser

Shafts

a) Riser Conduits

are used in medium sizedinstallations and consist of a series

of metal cabinets called splicing

cabinets aligned vertically through

the building, one on each floor and

connected by a vertical conduit.

b) Riser Shafts

are required for very large

installations and consist of a series

of individual full length

interconnecting closets called

splicing closets which are aligned

vertically one on each floor and eachfitted with a fire proof access door.

Slots on the floor, forms a clear and

broken opening from top to bottom

of the building.

1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and






1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


RISER

CONDUITS

FLOOR

CONDUITS

SPLICING

CABINET

WALL

OUTLET

DISTRIBUTION

CABINET

RISER

SHAFTS

MAIN TERMINAL

TELEPHONE CABINET

COMMUNICATIONS & SIGNAL SYSTEMS




1.8.2 Types of Telephone

System

1. Single-Line Phones. These arebasic telephones, just like the ones

in an average home, that can be

bought at an appliance store and

have no additional extensions, no

transfer capabilities, and are analog

units that hook up directly into a jack

in the wall. These are best in homeoffices or businesses that do not

need multiple lines. Additional

features can be added through your

local phone company, such as call

waiting and three-way calling. If you

prefer not to utilize your phone

company's voice mail service, an

answering machine can be

purchased to handle missed phone

calls.

1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


2. Small Business Multiple-Line

Phones. A small business that has

moderate-to-large phone traffic will

need a phone system that can

handle all calls efficiently. A multiple-line phone with two or more

extensions (depending on how many

people are in the office), along with

a digital line hookup, can manage a

small office effectively. A voice mail

system with 2-10 ports can be used

to keep the office from missing

phone calls.

3. Large Business Multiple-Line

Calls. A business that has over 50

employees with a large number of

phone calls needs a large phone

system, one that can hold up tohundreds of outside lines, with an

even larger number of extensions.

Through this phone system, one or

more T1 lines (see below) are

necessary to effectively handle the

load, and the voice mail system will

need a large number of ports.

COMMUNICATIONS & SIGNAL SYSTEMS




1.8.2 Types of Phone Lines

Analog. An analog line has four

grooves on the center of the connector,

in which the middle two conductors,known as the "tip" and the "ring",

connect a phone line, while the outer

two would be for a second line.

All modems require an analog line.

Phone lines that are in an industrial

building will connect to a PBX, a

telephone switch within the building,and analog lines always work on a

PBX. If you are using phones that do

not have multiple lines or digital

displays, then an analog line will work

for your system.

Digital. A digital line has 6-8 grooveson its connector, and is used for

phones with multiple lines and phones

with digital status indicators.

1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


If your phone system has either of

these, and your business is not big

enough to merit the use of a T1 line,

then a digital line is for you. In an

industrial building, however, most (notall) PBX's can connect to digital lines,

so confirm this with building operations

before trying to run a digital line.

T1. This is a powerful phone line that

acts as a tube to funnel information at

a fast rate. A T1 line consists of 24channels, each channel handling

64,000 bits per second. Each channel

can be configured to your

specifications, whether it is for voice

mail or data traffic. In business, T1's

are popular as a leased line, which

means that they are a permanenttelephone connection set up between

two points (for example, if your

business has offices in different

buildings in a business complex, a T1

connection would be necessary for

direct access). T1 leased lines are

always an active line between the twoplaces.

0 COMMUNICATIONS & SIGNAL SYSTEMS




1.8.2 Phone System

Hardware

PBX Server. The PBX server is aprivate telephone switchboard that

serves a designated group of users

(like a building). The server provides

on-premises dial service and can

provide local and trunked

communication network connections.

The Control Unit. A control unit is

the nerve center of a phone system

within your office, where all of the

individual lines connect and all calls

get routed. While a residential phone

line may be hooked up to an analog

service, a small business server isusually handled digitally, with larger

businesses requiring a T1 line.

Depending on the size of your

company and the telephone usage of

your business, this will decide whether

analog or digital would be best.

1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


Individual Units. For each person

who will have an extension in your

office, an individual phone will be

needed. An individual unit can have

multiple lines, but depending on thenumber of employees your company

has, each unit may not have all of the

lines available to them. Everybody in

the company does not need to have a

phone unit that has all incoming lines

available, as this could reach up to

several hundred lines in a largecompany.

IP Telephony. This is the latest

technology in phone systems, where

your server would run through your

computer network. One of the options

of this is a PBX server on a disk. Oneof the early problems with this system

is that other systems on your network

(e.g., a printer) may clog up your

system, causing phone calls to be

missed because they can not get

through the system. This is a problem

that should be fixed within the nextcouple of years.

1 0 COMMUNICATIONS & SIGNAL SYSTEMS




1.8.2 Phone System

Features

Call Waiting Or MultipleLines. Depending on the system that

you use, your phone may either have

call waiting or multiple lines. If

individual units only have one line,

then call waiting is necessary to keep

lines clear. Multiple lines avoid this

problem, as long as calls on each linecan be put on hold.

Conference Calling. Conference

calling gives a person the ability to add

a third party to a phone call. This gives

the user the ability to hold long-

distance meetings without the need tohave two of the parties in the same

place. When two people are on the

phone and a third is on hold, the third

can be entered into the conversation

through this service. The service can

also allow the first party to disconnect

and let the second and third partiescontinue talking. .

1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


Call Attendant. A call attendant

handles all phone calls directly before

transferring the calls to extensions.

Through this, a list of all employees'

extensions can be given (allowingcallers to transfer to the right

extension), calls can be put on hold if

all lines are busy, or could send calls to

voice mail if the extension transferred

to does not answer. A call attendant is

set up to even play background music

while callers are on hold.

Hands Free Calling. Hands free, or

speaker phones, give a person the

opportunity to talk on the phone

without holding the receiver, not only

giving the user the option of moving

around the office while talking, but alsoallows for several people to hear a

phone call at once.





1.8.2 Phone System

Features

Speed Dialing. This feature allowsthe user to keep multiple phone

numbers saved, allowing one-button

dialing. Speed dialing is best for

domestic long distance and

international numbers, where

additional codes must be dialed, but it

also is great for numbers that aredialed constantly.

Redial. Like speed dial, redial saves

time by allowing you to simply press

one button to make a call to the last

number dialed.

Caller ID. Know who is calling before

you pick up the phone. Caller ID willtell you who is calling by showing

what phone number or extension the

call is coming from, on a digital display

usually within the phone unit itself. If it

is important to have knowledge of

outside phone numbers, make that an

extra that must be on the system.

1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


Number Blocks. Number blocks

keep employees from taking

advantage of the phone. A number

block will block out calls to specific

area codes (such as 900 toll calls), andcan keep phone calls limited to

interoffice if necessary.

Voice Mail. Along with a company

voice mail on the control unit, each

individual unit has its own personal

voice mail. These voice mailboxes can

be coded to keep other employeesfrom hearing messages, and both the

control unit and the individual units can

transfer messages directly into a

mailbox. Individual voice mailboxes

gives employees the ability to check

their individual messages from outside

of the office, and also allows theemployee to leave a personalized

message for incoming calls. Another

option to voice mail is a call log, which

keeps a numeric log of calls you

missed and allows the user to return

the missed call with the press of a

button.





1.8.2 Phone System

Features

Call Transfer. This feature allowscalls to be sent directly to specific

extensions. This way, only one phone

number is needed for the company,

and if there is no single person at the

company to answer phones, anyone

can answer the line and transfer the

call to the appropriate person. It also ishelpful when one person needs to

speak to several people within your

company. On a control unit, a "night"

switch can be used to directly send

calls to voice mail when there is no

one in the office.

Remote Door Entry. This allows the

phone user to allow access to the front

door from the phone with the push of a

button. This is best for companies that

do not want open access to their

business, or one where valuables

need to be protected.

1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


Surge Protection. Like a computer,

an electrical surge can damage a

phone system, causing memory and

important codes to be lost. Surge

protection prevents this fromhappening.

Battery Backup. This allows the

phone system to operate for a short

period of time if power leaves the

building. Usually a backup will keep

phone use for anywhere between 30minutes to an hour.





1.8.2 Accessories

Headsets. An option to hands-free

calling is headset equipment, which

allows the user to keep the

conversation private without having

to hold the receiver. Headsets are a

health advantage as well, as they

have also been known to decrease

neck pain for users who bend

awkwardly to rest the phonereceiver on their shoulder.

Intercom System. An intercom

system can page employees away

from their own phone. This is

popular for in service-oriented

businesses, where employees mightnot be sitting in an office in reach of

a telephone.

1.1 General

1.2 Fire Alarm

System

1.3 Intrusion

(Burglar) Alarm

System

1.4 Sprinkler Alarm

1.5 Industrial

Building Security

System

1.6 Television

Antenna System

1.7 Sound

Amplifying Systems

or Public Address

System

1.8 Telephone and


Message Keyboard. This is a tool

used to send messages from one

employee to another when the

receiving party is on another call or

in a meeting. Through a codesystem and a regular keyboard,

users can send text messages

instantly and receive replies without

interrupting their call.



END

COMMUNICATIONS

AND SIGNAL

SYSTEMS

communication & signal

Documents