User`s guide

Positioning the Radio Modem
In order to achieve maximum operational reliability and range from your radio modems
it is important to reduce the possible effects of RF interference on them.
Each radio modem has an antenna protruding from the top of the case. This antenna
is used for both receiving and transmitting data. This antenna will provide adequate
range and reliability for most applications. However, in order to improve the range and
reliability of the radio modem RF link it is advised that the following guidelines be
understood and implemented where possible.
• Free space around the antenna is as important as the antenna itself.
• The optimum orientation of the antenna is directly upward.
• Do not mount the radio modem directly on or against metal surfaces. Close
proximity to metal surfaces can cause degradation and reflection of the radio
signal which will severely undermine the performance of the radio modem.
• Ensure the antenna is kept away from potential sources of RF interference such
as electrical wiring, transformers, batteries and other items of electronic
equipment.
• Where possible ensure the Radio Modems are placed well above head height.
The higher the better!
It is wise to try different locations and positions for the radio modem before
permanently mounting it. When trying out different positions, if you are holding the
radio modem, do not hold it by the antenna and keep it well away from your body
(preferably above your head) in order to reduce potential shielding of the radio signal.
A few centimetres difference in the location of the radio modem can sometimes
(depending on surrounding furniture, walls and equipment) make all the difference
between a reliable link and a link that is prone to constant errors and lost packets.
Potential RF Interference
The radio modem is a sensitive piece of electronic equipment, which may from time to
time be affected by other radio transmitting devices operating in close proximity. Such
devices include microwave ovens, mobile phones and radio transmitter. If erratic
behaviour or erroneous data is observed, try turning off the source of interference or
moving the radio modem away from that device.
Direct mounting of the radio modems to the case of computers, printers and monitors
is not advised due to potential RF interference.
A word of caution: Computers, printers and other microprocessor based equipment
are renown for being big generators of RF interference. Ensure the radio modem is
situated as far away from these devices as is practically possible. Keep in mind
however that running an excessively long serial cable to the radio modem can produce
unreliable communications between the terminal equipment and radio modem.
Operating Problems
A number of factors can affect the successful operation of a Radio Modem link. Most
of the problems are related to either radio interference or an inadequate radio path.
Prior to deploying a new installation, a bench test of the system is highly
recommended as a method of eliminating basic operational and system configuration
User’s Guide Installation 2-4