RADIO PAGING SYSTEMS

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15 Νοε 2013 (πριν από 3 χρόνια και 6 μήνες)

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RADIO PAGING SYSTEMS




MAY 8, 2013

Presented by: Rey Freeman

Agenda


The Need for Paging


Paging System Challenges


Types of Paging Systems


Technical Overview


Case Studies


Summary


The Need for Radio Paging


All Public Safety agencies have the need for an
immediate, easy to operate, wide area “One to
Many” emergency radio alerting system


This can be accomplished through the agency’s
primary voice system, or through a separate,
independent system:


Private (customer
-
owned, usually analog Tone & Voice)


Commercial (typically “Digital” Alpha
-
Numeric)


Pagers are cheaper than radios, and easier to carry
on a day
-
to
-
day basis than portable radios

The Need for Radio Paging


Historically, this paging has been conducted on the
city or county’s “Fire Main” radio channel


However, busier agencies have found that this often
interferes with the voice traffic from responding
agencies and other dispatch calls


As agencies move to the ARMER network, this
presents a new challenge, because the ARMER system
does not
support paging capabilities


What are the options and solutions?


The Need for Radio Paging


Most public safety agencies have a specific
geographical service area to be addressed:


Typical city: 5 to 60 square miles


Typical county: 170 to 6,000 square miles


For many years, the most common type of system was
to send “Tone and Voice” paging tones and voice
broadcasts over the agencies Fire or Fire/EMS main
radio channel


The Need for Radio Paging


Tone and Voice systems can be “Low Tech” (1


3
individual tower sites) or “High Tech” (Simulcast, many
tower sites)


These methods have served agencies reasonably well,
but user’s needs and expectations have changed, and
the use of 800 MHz for dispatch requires that
changes be made


The ARMER system is not capable of Tone & Voice or
Alpha
-
Numeric paging…but why?

Paging System Needs and Challenges


A paging systems needs to provide reliable
coverage throughout its intended service area:


Outdoors/On
-
Street


In
-
Building


It also needs to achieve a balance between cost and
performance for the system’s users


Most paging networks are a one
-
way system; the
pager is a radio receiver only…it has no transmitter,
and cannot “talk back” to a tower site


Typical Tone & Voice Radio Paging System

Tower A

Tower B

Why Can’t We Use ARMER?


The ARMER network is an 800 MHz, P25 digital,
two
-
way

radio system. It is “two
-
way” in terms of
the “data exchange” between the system and
radios, as well as the actual voice traffic


All radios on the ARMER network are constantly
communicating with the network (via the control
channel) about signal strength, talk groups, & other
data


Pagers are receive
-
only (with minor commercial
exception)


Control Channel continuously
transmits system data to all radios

PD

CH 1

ARMER

Controller

TX

RX

CH 2

RX

TX

CH 3

RX

TX

CH 4

RX

TX

CH 28

RX

TX

Control

Channel

FD

EMS

CH 1

ARMER

Controller

TX

RX

CH 2

RX

TX

CH 3

RX

TX

CH 4

RX

TX

CH 28

RX

TX

Control

Channel

FD

Radio user presses TX button, and radio information
is sent via control channel to ARMER Controller

ARMER Controller processes inbound request, and sends repeater
channel command (CH 3) back to all radios selected on same Talk Group

CH 1

ARMER

Controller

TX

RX

CH 2

RX

TX

CH 3

RX

TX

CH 4

RX

TX

CH 28

RX

TX

Control

Channel

FD

FD

CH 1

ARMER

Controller

TX

RX

CH 2

RX

TX

CH 3

RX

TX

CH 4

RX

TX

CH 28

RX

TX

Control

Channel

FD

FD

Originating radio user’s radio automatically switches to correct voice channel
and begins transmitting; All radios selected on same Talk Group do the same
and hear the voice transmission

When transmission is completed, all units revert
back to Control Channel


CH 1

ARMER

Controller

TX

RX

CH 2

RX

TX

CH 3

RX

TX

CH 4

RX

TX

CH 28

RX

TX

Control

Channel

FD

FD

Why Can’t We Use ARMER?


Because the pagers are receive
-
only, they have no
way to talk back into the network


The ARMER system would not know which tower sites
to activate for paging of field units


The type of digital modulation used in the P25
ARMER system
is not the same

as Alpha
-
Numeric
systems


No manufacturer makes 800 MHz digital pagers


As such, another solution must be implemented…

Types of Paging Systems


The two primary options for public safety paging are:


Tone and Voice (analog VHF, UHF)


Alphanumeric (digital VHF, UHF)


When considering the design of a paging system, the
two
coverage technologies

to be considered are:


Multicast (less expensive)


Simulcast (more expensive)


What are the pros and cons of each system type, and
which is best for your operation?


Tone and Voice Paging


The Tone and Voice paging systems are by far the
most common in public safety


Each agency is assigned a unique “tone group”, which
allows the dispatch center to alert only the specific
agency or personnel needed for the event


Until the newer pagers (
Minitor

5) came along, special
code plans were needed to allow large “Group Calls”


Fire
Dept
: “A” tone 652.5 Hz, “B” tone 787.5 Hz


Rescue: “A” tone 607.5 Hz, “B” tone 787.5 Hz


Group: 787.5 Hz “Long Tone”

Tone and Voice Paging


The newer pagers now allow multiple codes, so this
level of planning is not necessarily required


The master Code Plan for the City or County pagers is
typically incorporated into the radio consoles in the
dispatch center


The dispatch console can be programmed to
automatically select the correct tower site closest to
the agency being paged



…which is not needed if a Simulcast system is being
used

Tone and Voice Paging: Pros & Cons


Generally speaking, it is the simplest and most basic
type of system; a 2
-
tone tone code alerts a group of
pagers, and the voice broadcast is heard by all
members of the group


Voice Storage built into newer pagers resolves much
of previous concerns with missing pages


Pagers can be used to monitor other radio channel
activity…until ARMER has been implemented


Pagers are priced in the $450 range, depending on
options; multiple vendor options available



Tone and Voice Paging: Pros & Cons


Most paging systems were significantly affected by
FCC “
Narrowbanding
” conversion (~20% range loss)

Motorola
Minitor

5


8
-
tone code capability


2
-
group call capability


8 minute voice storage (option)


2
-
frequency operation (option)


Loud audio!!


Other brands are available


Apollo VP100/200


Sceptar
?

Alpha
-
Numeric “Digital” Paging


Pagers provide a alert tone and text display of the
emergency call information, rather than voice
broadcast from the dispatcher


The dispatcher enters the call data into a computer
workstation


Most of these systems are hosted by a commercial
vendor, although private systems are possible


Each agency is assigned a unique address, which
allows the dispatch center to alert only the specific
agency or personnel needed for the event


Group calls are a standard feature

Alpha
-
Numeric Paging: Pros & Cons


The text messages are routed from the dispatch center
via the internet or other method to the paging system’s
host “terminal”, and then routed to the system’s tower
sites


Some dispatchers prefer Alphanumeric systems
because it allows them to enter and send the call data
while talking on the phone with the caller


Some agency personnel prefer these systems because
the call data is stored and can easily be read again
when enroute to the call


These commercial systems have wide area, and often
Statewide coverage

Alpha
-
Numeric Paging: Pros & Cons

Range Paging of
Minnesota

Alpha
-
Numeric Paging: Pros & Cons


Because these systems are usually hosted by a
commercial vendor, the public safety pages may not
be sent through the network immediately


Some providers will allow public safety “Priority”


Monthly service fee is required…


…but the city/county does not have to build their own
paging system


Pagers are typically less expensive than Tone and
Voice pagers (~$150)

Alphanumeric Pagers

Motorola Advisor Elite

Apollo Pilot

Paging System Technology


When designing a paging system, the two radio
coverage technologies to be considered are:


Multicast (less complex and expensive)


Simulcast (more complex and expensive)


We will focus on how these work for Tone & Voice
systems


Each technology relies on VHF or UHF transmissions
from multiple tower sites

Multicast Paging Technology


A Multicast system uses two or more tower sites,
operating on the same VHF or UHF frequency, to send
Tone and Voice transmissions to field units


Though each site operates on the same frequency, they
cannot transmit at the same time
, as this would cause
interference


The tower sites are usually selected to cover a specific
geographical service area


The tower sites may be manually selected by the
dispatcher, or automatically programmed into console

Multicast Paging Technology


The tower sites need to be linked back to the dispatch
center, which can be done through:


VHF on
-
channel RF control stations


UHF RF links


Microwave radio links


Other technologies?


Much lower cost than Simulcast (~$20,000 per tower
site)

Multicast Case Study: Lyon Co MN


Lyon County migrated public safety agencies to
ARMER operation in late 2012


A new VHF Paging System was needed to replace old
wideband system


UHF Link system installed to connect Paging sites


Five tower sites:


Marshall (ARMER tower)


Minneota

(local ARMER tower)


Cottonwood (water tower)


Russell (ARMER tower)


Tracy (ARMER tower)

Multicast Case Study: Lyon Co MN

Simulcast Paging Technology


A Simulcast system uses two or more tower sites,
operating on the same VHF or UHF frequency, to send
Tone and Voice transmissions to field units


Each site operates on the same frequency, and
transmits at the same time
, with little or no interference


No tower site “selection” is needed


Provides much greater overall coverage, as pagers
will often receive signals from multiple sites


Greatly simplifies dispatcher operations

Simulcast Paging Technology


So…how do the sites transmit on the same frequency
at the same time without interference??


Technology:


GPS timing at each tower site


High
-
stability frequency reference


Audio timing (delay) at each site to “align” the audio from
the towers


Management of the signals and audio timing are
extremely critical to avoid problems in “overlap” areas


$60,000 equipment cost per tower site

Simulcast Paging Technology

Tower A

Tower B

Overlap Zone

18 miles (max)

Simulcast Case Study: Aitkin Co MN


Aitkin County migrated public safety agencies to ARMER
operation in March 2013


A new VHF Paging System was needed to replace old
wideband system


Paging sites connected via ARMER microwave network


Seven tower sites:


Glenn (ARMER tower)


GRE (local Utility tower)


Lawler


Logan (ARMER tower


Quadna

(ARMER tower)


Sandy Lake(ARMER tower)


White Pine (ARMER tower)

Simulcast Case Study: Aitkin Co MN

Paging Summary


Paging systems can be either Tone & Voice or
Alpha
-
Numeric


Either Multicast or Simulcast technology can be used


Multicast: Less complex, less expensive, less coverage


Simulcast: More complex, more expensive, more
coverage


800 MHz ARMER does not support paging


What about Cellular text options? Now being used
as a backup by some agencies


Discussion

and

Questions

Radio Paging Systems