Figure 1-1 Communication… In a Nutshell
1. An alarm occurs at the
protected premises.
2. Moments later, the Security
System’s Digital Communicator
(which is connected to the
telephone network) goes “off-
hook” and automatically dials
the phone number of the Digital
Receiver at the Central Station
(with which it has been
programmed).
3. When the Digital Receiver
answers the call, it produces a
“Handshake” tone that invites
the Digital Communicator to
transmit the alarm (or other
information),
4. Once the “Handshake” is
received, the communicator
transmits the required data.
5. When received at the Central
Station, the information is checked
for accuracy.
6. If found to be “legitimate,” the
Digital Receiver produces a
“Kissoff” tone that instructs the
Digital Communicator to go “on
hook” and release the line.
7. If the Central Station has a
computer-based Automation
System, the raw data processed
by the Digital Receiver is utilized
to access a Database and provide
meaningful information to the
Central Station’s operators.
Digital Communicators and
Communication Formats
Unfortunately, manufacturers of security equipment have
not always been able to agree on the best way to
communicate data between a protected premises and a
Central Station. As a result, a variety of different
communication formats or "protocols" have emerged
–
each
claiming to have particular distinctions or advantages over
the others. To be effective, the CP-220A Digital Receiver
must be able to process communications from a wide range
of security products produced by many different
manufacturers. Fortunately, Digital Receivers like the
CP-220A have the "intelligence" to recognize the different
communication protocols it receives and make the proper
adjustments so it can correctly interpret the data
–
all
automatically and transparently to the operator.
Page 1-2
Section 1: Getting Acquainted CP-220A Central Station Receiver
Hook-Up
and
Installation
Manual
The Communication Process
A Digital Communicator
(also known as a
Digital Dialer
) is a device incorporated into
security systems and used to report alarms
and other information – over the standard
telephone network – to Central Station
Receivers, such as the
FBI CP-220A
.
Typically, when activated by the security
system, its
Digital Communicator will
automatically call one of the phone lines
assigned to the Central Station’s Receiver.
Once the CP-220A senses the telephone
company’s
ring signal, it waits for the pre-
programmed number of rings, answers the
active phone line, pauses for a pre-
programmed time interval, and then causes
the corresponding
Line Card to deliver a pre-
programmed
handshake tone(s), which invites
communication from the subscriber’s
premises. At the point that the CP-220A
“picks up” the line, the “On-Line” LED (see
page 1-9) lights, indicating which of the (up to
8)
Phone Lines/Line Card combinations is
processing the call.
Once it receives the appropriate handshake,
the Digital Communicator proceeds with the
data transmission. After the CP-220A
verifies
the data (see
Appendix B), it delivers the
appropriate
Kissoff tone, causing the
communicator to shut down unless there is
more data to be communicated. In such
cases, additional “rounds” of data and
subsequent
Kissoff tones may occur. After the
final
Kissoff, the CP-220A releases the phone
line and passes the data on to its display
and/or to any peripheral device(s) to which it
may be connected.
Note that each of the
Line Cards can stack up
to 12 subscriber phone calls in the event that
multiple Line Cards are accepting data at the
same time. All incoming data is processed on
a
first come, first served basis.
Because such information is in “raw” form and
must be interpreted, most Central Stations
employ an
Automation System, which, through
means of a computer, uses this data to access
a customer Database that converts such “raw”
information into a readable format that can be
easily understood and acted upon by the
Central Station’s operators.
Each CP-220A provides an
Automatic and a
Manual mode of operation (see page 2-103).
In the
Automatic Mode, the transmitted data
will
not be displayed by the receiver, but will
be passed on to an attached
Printer and/or
Automation System (see below) if it exists. If
operated in
its Manual Mode, the CP-220A will
display all the data it receives, but requires
operator intervention.
The CP-220A can be programmed to display
English Language (see PARAMETER 28 on
page 2-19), including the subscriber’s
Account
Number and the wording used to represent
various alarm and trouble conditions.
