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920MHz Band Wireless Device (Korea) USERS MANUAL EM-9121 Rev. 1
9.5 INTERFERENCE TO RADIO WAVES
(1) NATURAL NOISES CAUSED BY LIGHTNING, STATIC ELECTRICITY, OR SOLAR RADIATION
• Noise caused by lightning may affect radio communications.
• Because of radio property, rain has little influence on radio communications.
However, radio reachability can be affected when a water layer is formed by rainwater or snow accumulated on the metal
plate surface to which the rooftop antenna is attached.
(2) RADIO WAVE INTERFERENCE
• Interference from a third party:
Reception sensitivity may be deteriorated or interference may occur due to radio waves emitted from third party wireless
devices.
For example, radio interference may occur when other wireless devices using the same radio frequencies are present in the
vicinity.
• Self-interference (multipath fading):
Radio propagation path (diffracted wave, reflected wave, transparent wave) can affect radio communication.
Radio wave can travel directly to a receiver but often reaches the receiver after being reflected by surrounding objects.
So-called 'multipath fading' occurs when radio waves which have arrived at the receiver through respective paths interfere
with each other, resulting in affecting the reception level of the radio waves.
'Fading' is a phenomenon in which the reception level varies due to movement of a wireless device and/or with time.
(3) INFLUENCE OF OBSTACLES
• Radio wave status can change significantly due to the location of antenna within the installation site and objects in the vicin-
ity which may shield radio waves.
• Radio wave transmission/reception environment may change due to new obstacles (trees, constructions, etc.) which were
not present when wireless devices were initially installed.
(4) SPURIOUS RADIATION FROM ELECTRONIC EQUIPMENT
• A source of electromagnetic waves or magnetized object in the vicinity can cause noise and may affect radio communica-
tion.