1. Multiple transmitter signal
paths can cause nulls.
a. True
b. False
2. Diverse (Dual) antennas are
used on a receiver to:
a. extend range.
b. provide supervision.
c. reduce nulls.
d. All of the above
3. Which of the following
frequencies are used for
security wireless systems?
a. 300 MHz
b. 450 MHz
c. 900 MHz
d. All of the above
4. A fully supervised wireless
system monitors the:
a. condition of the battery.
b. status of the device
(door open/closed).
c. functionality of the
transmitter.
d. All of the above
5. As the frequency increases,
the wavelength decreases.
a. True
b. False
6. Which of the following
construction materials will
reflect RF signals?
a. Wood paneling
b. Sheetrock
c. Bulletproof glazing
d. Metal ducts
e. All of the above
7. Trees and vegetation have
no effect on RF signals.
a. True
b. False
8. A burglar alarm control
panel must be specifically
designed to accommodate
wireless devices.
a. True
b. False
9. Wireless transmitters
can include a:
a. motion detector.
b. smoke detector.
c. glass break detector.
d. door/window contact.
e. All of the above
10. The orientation of the
receiver’s antenna is
not important.
a. True
b. False
11. Which of the following
can affect the usable
life of the battery in a
wireless transmitter?
a. Environment
b. Usage
c. Device type
d. All of the above
12. All wireless systems are
fully supervised.
a. True
b. False
13. Wireless devices are
designed only for
indoor use.
a. True
b. False
14. Signal strength is the only
factor to consider when
determining the reliability
of a transmitter.
a. True
b. False
15. Wireless systems
can provide:
a. tracking and location.
b. man-down alerts.
c. a virtual fence.
d. Any of the above
What’s Wrong with This?
Wally `Larman installed a wireless system for an auto parts store. He installed the devices as shown in this diagram and tested all transmitters. A few days later, his customer called and told Wally that frequently the keypad would display trouble for some of the transmitters. Can you see what Wally did wrong and what he must do to correct the problem?
Here are the answers to the 5-Minute Tech Quiz and What's Wrong with This?
1. a
2. c
3. d
4. d – Each of these should be monitored for maximum supervision. Not all wireless systems monitor the status of the door/window, but this is important information when a user is arming the system.
5. a – As the frequency increases, the wavelength does decrease. For example, the wavelength of 300 MHz is approximately 20 feet while the wavelength for 900 MHz is approximately 1 foot.
6. d
7. b – Trees and vegetation will absorb some of the energy and reduce range.
8. b – Although some controls are specifically designed to accommodate wireless devices, it is possible to add fully supervised wireless devices to any hard-wired panel.
9. e – In addition to these types of transmitters, heat, manual fire, panic and universal transmitters also are available.
10. b
11. d
12. b – Some systems monitor only the battery condition while others do not monitor any functions at all.
13. b
14. b – The background RF “noise level” also is an important consideration, because a high level of RF noise can overpower the security transmitters.
15. d
Answer to: What’s Wrong with This?
Wally’s problem is caused by where he located the wireless receiver. Electric and HVAC rooms typically contain large metal ducts, enclosures and generally have a high level of RF noise from the motors and electric panels. Additionally, the machine shop is located in an adjacent room, which also will generate large amounts of RF interference. Wally should relocate the receiver to the closet as shown in this diagram and retest the system.
It always is a good idea when installing a wireless system to locate the receiver near the center of all transmitters to provide the best coverage. As with all security systems, you should evaluate carefully the area to be protected to uncover any possible sources of
interference and locate the equipment accordingly.
