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Signal strength and radio frequency range
receives data, the LED is solid during the configured time.
Note
Received Signal Strength (DB) parameter
The RSSI value can also be obtained by reading the XBee DB parameter value. It represents the RSSI
absolute value of the last received data packet expressed in hexadecimal notation.
Is RSSI the best indication of link quality?
One thing to keep in mind is that the RSSI is only an indication of the RF energy detected at the
antenna port. The power level reported could be artificially high because it may include energy from
background noise and interference as well as the energy from the desired signal. This situation is
worse in an interference-prone environment where it is possible to get consistently high RSSI
readings, yet still have communication errors.
If the application is attempting to measure "link reliability" and not just "signal strength," it may be
helpful to factor in "% packets received" or similar data.
Tip
A range test is always a good idea, as it allows you to measure link performance in terms of
signal strength and packet success rate. This will help you determine the reliability of your RF system.
For more information, see
Range test
Since the communication between XBee modules takes place over the air, the quality of the wireless
signal can be affected by many factors: absorption, reflection of waves, line-of-sight issues, antenna
style and location, etc.
A range test demonstrates the real-world RF range and link quality between two XBee modules in the
same network. Performing a range test will give an initial indication of the expected communication
performance of the kit components.
When deploying an actual network, multiple range tests are recommended to analyze varying
conditions in your application.
XCTU allows you to perform a range test with at least one XBee module connected to your computer
(local) and another remote XBee module, both in the same network. The range test involves sending
data packets from the local XBee module to the remote and waiting for the echo to be sent from the
remote to the local. During this process, XCTU counts the number of packets sent and received by the
local module and measures the signal strength of both sides (RSSI):
RSSI is the Received Signal Strength Indicator value.
n
Every sent packet from the local XBee module should be received again as an echo by the same
n
local XBee module.
XBee-PRO 900HP DigiMesh Kit User Guide
Example: perform a range
test.
Range test
137
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