10 Tips to Reliable Wireless Systems

5. Keep the receiver above ground if possible to avoid attenuation

Another consideration when choosing a mounting location for the wireless panel or receiver is its relative position to the Earth’s surface. The RF radio energy that security transmitters commonly emit is classified as a surface wave, which is actually a ground wave. Surface waves can experience attenuation when they travel any distance over the Earth. This is because RF energy will induce a slight voltage over its surface.

Objects positioned between the transmitter and receiver also attenuate radio waves. This is especially true at the frequencies most commonly used in today’s short-range wireless systems. The bottom line is to install the receiver above ground whenever possible. Also, as mentioned earlier, select a location as near to the center of the transmission field as possible.

6. Understand how low and high temperatures can affect transmission range

Not only can low or high ambient temperatures adversely affect transmission range, but they can also endanger battery-operated equipment. Batteries are not always agreeable with low temperatures. Operating voltage can drop when the temperature drops, but it can also rise above design parameters when the temperature rises above normal.

To avoid problems, always check the manufacturer’s installation instructions to determine the operating temperature of the wireless equipment you intend to use. By not exceeding the temperature rating of the transmitter, your systems will likely continue to operate trouble-free for years to come.

Such locations include freezer panic alarms and low-temperature sensors. When using wireless for these applications, always locate the radio transmitter outside of the cold area. The best solution is to place it in the rafters above the freezer unit, but never fasten it to the outside shell, which can exceed the suggested operating parameters of the transmitter.

High temperatures can also adversely affect transmitter operation. This is made possible when the electronic components inside the transmitter begin to change their electrical characteristics. This can cause the transmitter to go off frequency, leading to the receiver not “hearing” the RF transmissions.

7. Intermittent transmitter reception due to excessive range

Among the most serious problems encountered by security dealers is an intermittent transmitter problem due to excessive distance between a transmitter and receiver. This can result in the receiver missing radio transmissions or prematurely activating a trouble or alarm condition when there are none to report.

To solve the issue of excessive range, always review the manufacturer’s installation instructions to establish the accepted distance between the wireless panel/receiver and transmitters. As stated earlier, try to position the receiver above ground in the middle of the building for optimal signal reception.

To make certain you do not have to remount transmitters in the field, test for signal strength and signal-to-noise when the wireless alarm system you’re usi
ng offers this handy utility.

8. Align transmitter and receiver antennas for proper reception.

Intermittent reception can also be caused when the transmitter and receiver antennas are misaligned. To solve the issue of antenna orientation, try testing the transmitter before you fasten it to the window or door trim. If it’s already fastened, remove and test it in the opposite position. In other words, if the transmitter is mounted in an upright (vertical) position, hold it in a horizontal plane when testing it again.

Physical position can and will adversely affect transmission characteristics. So, if the receiver’s antenna is not in alignment with the transmitter antenna it may not receive enough energy to excite the initial stages inside the receiver. Whatever you do, do not move the receiver or you could jeopardize the correct operation of the other transmitters.

Antenna alignment is related to wave polarization. For more on polarization, see sidebar.

9. Avoid metal construction when installing transmitters and receivers

Try not to install your transmitters or the receiver/control panel next to metal construction. When positioning the alarm panel, avoid the metal ductwork used in forced air heating systems.

Transmitters should be installed on nonmetallic surfaces, such as wood or aluminum. Aluminum will not adversely affect signal strength as steel construction does. Always test your transmitters with the wireless control panel before mounting them physically to the structure. This will ensure reception before drilling holes and fastening them.

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