Alarm Basics, Part 4
The security of the line that carries your store's alarm signal to
your alarm company is the linchpin of the whole system
by DAVID SEXTON, CPCU
JEWELERS MUTUAL INSURANCE CO.
The transmission of alarm signals is perhaps the most complicated, least
understood component of burglar alarm systems. Sophisticated electronic
surveillance is worthless if your system fails to inform the proper parties
of an intruder.
While some jewelers in less-populated areas may use security systems
that trigger a bell heard only inside or immediately outside the store,
many use systems that also transmit signals to a monitoring facility, such
as a police department or UL central station.
Following is an overview of the alarm transmission methods UL recognizes.
You may find this information helpful when speaking with your alarm company
representative or insurance agent.
UL certifies seven alarm signal transmission methods. The following methods
send signals over regular telephone lines: direct wire, McCulloh transmitter,
multiplex, digital alarm communicator and derived channel. Alarm signals
also can be transmitted by radio waves or cellular telephone. Some security
systems use two transmission methods to reduce the chance of a burglar interrupting
the alarm signal.
Here is a brief description of each transmission method (the first three
also should have separate line security to achieve maximum results - see
- Direct wire. A separate, dedicated telephone
wire connects the protected premises with the monitoring facility. Its
sole purpose is to carry the alarm signal. If you use a direct wire system,
be sure it includes line security. Otherwise, a skilled technician can
defeat it by approximating existing signals or substituting his own electrical
signals. This method may be sufficient for jewelry stores in non-urban
- McCulloh transmitter. Though not in widespread
use, this method uses a "party line" that connects several businesses
to a monitoring facility. When an alarm signal is received via the dedicated
party line, the monitoring facility checks a code to identify which business
was compromised. Unfortunately, this system can be compromised easily.
- Multiplex. This system also operates like
a "party line," using one dedicated telephone line to connect
several businesses to a monitoring facility. But the multiplex system is
not compromised as easily as the McCulloh.
- Derived local channel system. This system,
which inherently provides line security because of the way it operates,
uses the regular telephone company network and a dedicated telephone line
to carry signals. This arrangement provides continuous supervision of the
communication channel without interfering with normal telephone use. If
the telephone line is cut, an alarm signal is transmitted to a monitoring
- Radio system. This security system transmits
status signals via radio wave to a receiving antenna, which relays the
signal to the monitoring facility. In a two-way radio system, the monitoring
facility can receive the alarm system's status signal as well as send a
signal to ask for the status or confirm an alarm condition, thus, providing
line security. One-way radio does not provide line security and is used
less often for jewelry operations.
- Digital alarm communicator transmitter.
The alarm signal is transmitted over the business's regular telephone lines
(rather than over a dedicated line), which transmit them to the monitoring
facility. An intruder can compromise this system easily by cutting the
line. This is the most basic transmission method, but it may be enough
for stores in non-urban areas.
- Cellular alarm transmission system. This
system uses low-power cellular telephone transmission to send a signal
from the alarm system to the telephone company network. This can be an
effective transmission method in some parts of the country. While occasionally
used for primary transmission, it's more often a backup to transmission
by telephone lines.
There is no "right" choice for alarm transmission. To select
the best method for you, consider a variety of factors:
- The transmission methods available from alarm companies in your area.
- Your insurer's recommendations and requirements. Will one method reduce
your premium more than another?
- Your physical and procedural security.
- Your inventory and crime in your area.
David Sexton leads the large accounts underwriting department at Jewelers
Mutual Insurance Co., Neenah, WI. He also is a corporate member of UL's
Burglary Protection Council and the Central Station Alarm Association.
Many alarm systems incorporate line security to supervise the communication
channel, which transmits signals between your store and the UL central station
or remote monitoring facility. The line is supervised to detect a burglar's
attempt to compromise the signal and enter your store undetected.
The more advanced level of line security works on an "interrogate
and response" concept. The central station computer interrogates (sends
a message that asks what's happening). The alarm system at the store responds
with an appropriate message, such as:
- System is armed; everything is fine.
- System is not armed.
- System is armed and something is wrong.
If the central station does not receive a response, it interprets that
as an alarm condition.
There are two levels of line security: standard and encrypted. With encryption,
the signal is "scrambled" and a decoder is needed to read the
signal. The level of encryption available from alarm companies has yet to
be tested by independent third parties such as Underwriters Laboratories.
But encryption offers promise for the future.
Line security is available for direct wire, McCulloh and multiplex signaling
systems. Your insurance agent or an insurance company specializing in
jewelers block insurance coverage can help you evaluate the alternatives
and select the most cost-effective method.
Copyright © 1999 by Bond Communications.