Nuvo NV-WCPS Installation And User Manual page 23

Two numeric values will appear. The first is the LQI, Link Quality Index. This is a
measurement of the Bit Error Rate (BER) associated with the current packet being
received by the Coordinator from the WCP. The number value will range from 0 to 255,
with 255 being the best possible connection. This is a good measurement of the WCP
communication at any given time.
The second number is the RSSI, Received Signal Strength Indication. This could range
from approximately -100, being the optimal measurement, to +127. The RSSI
measurement is based on the peak (highest)energy level detected by the Coordinator
on the current frequency. Remember that signal energy at a given frequency can come
from any transmitter/interferer on that frequency. This can be a non-ZigBee, 802.15.4
interferer such as a WiFi transmitter or microwave.
LQI is measuring the reliability of a link to a particular Coordinator based on the bit
error rate of the current packet. Link reliability will decrease drastically as the bit error
rate increases. RSSI readings simply measure peak amounts of radio energy on the
channel over a given period, regardless of where that radio energy comes from.
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