Specifications

RF Products Crestron Best Practices

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Best Practices – RF Products Reference Guide – DOC. 6689E

phones ring and the lines are active; there may also be interference on the

2.4 GHz.

NOTE: As long as Bluetooth does not consist of the majority of RF

devices in the system, any Bluetooth device kept beyond a meter from any

access point does not pose much interference in the 802.15.4 network.

4. If the wireless equipment is to be used in a room greater than 1,000 square

feet, repeat steps 2 and 3 in various locations within the room.

5. If the wireless equipment is to be used in multiple rooms, repeat steps

1 through 4 in each room.

When the reading is complete, Chanalyzer shows the results in a clean and

easy-to-read view of the signal over the entire 2.4 GHz band as shown in the

following example.

Sample Chanalyzer Capture of Total RF Interference

In the graph above, the range of wireless signals is roughly -110 dBm up to -20 dBm

(-20 dBm indicates a very strong signal).

NOTE A good rule to follow is that if almost the entire signal is below -80 dBm, the

channel is good.

Wi-Fi channels 1, 6, and 11 are highlighted in the sample site survey above. The

sample shows that Wi-Fi networks are operating on channel 1 and channel 11, and

that the channel 11 network is farther away. By visual inspection of the graph, note

that channel 6 is the most free, followed by channel 11. Wi-Fi channel 1 has some

minor signals above -80 dBm, which may be fine, but may cause reliability issues for

any Wi-Fi devices using that channel or any 802.15.4 devices using channels 11–14.

The following sections provide examples of various types of interference.

Cordless Phone Interference

The following is an example of 2.4 GHz cordless phone interference. There are very

high peaks of interference at levels of -40 dBm and above. This level of interference

affects all three non-overlapping Wi-Fi channels significantly and causes

interference issues with any equipment installed in the 2.4 GHz range. In this

scenario, the offending device should be removed or should be replaced with a

comparable device that operates in a different band (900 MHz or 5.8 GHz) to

provide a reliable installation. Wireless performance in the 2.4 GHz range cannot be

guaranteed with outside devices that create such a large amount of interference.