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A2541R24x
– User’s Manual
Release Date 11/22/13
assessment) will enable the user to find channels with minimal interference from WLAN devices.
Figure 4 WLAN channels
2.2.2.
Classic Bluetooth
Classic Bluetooth divides the 2.402-2.480 GHz band into 79 channels, each of which is 1MHz
wide. However, since Bluetooth changes channels rapidly (up to 1600 times a second), it is
unlikely to cause continuous interference in a specific channel and can be overcome by
implementing a simple acknowledge/retransmit functionality.
2.2.3.
Microwave ovens
A typical microwave oven uses a self-oscillating magnetron with a duty cycle below 50%,
because the tube is completely off for half of every AC mains cycle (8.33 ms in 60 Hz countries
and 10 ms in 50 Hz countries). The frequency of the microwave oven changes cyclically within
each AC mains synchronized on period, and is generally not predictable.
The user is encouraged to have packet transmission durations less than half the AC mains
period and implement an acknowledge/retransmit method.
2.2.4.
Other Interference
Systems similar to the user’s system may also exist within range and may also be a source of
interference; some typical applications to consider are:
Alarm systems
o
These typically use low duty cycles and are therefore easy to avoid using
acknowledge/retransmit methods
Car alarms (internal motion sensors)
Video surveillance
o
These are typically operated on a fixed channel, determined at installation time
and can be avoided by using clear channel assessment. It may be useful to
change the channel used by the video surveillance equipment also, if possible.
