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© 2021 Enphase Energy. All rights reserved. Enphase, the Enphase logo, IQ8 microinverters,
and other names are trademarks of Enphase Energy, Inc. Data subject to change.
ZRT-UM-0001-01-EN-US-2021-12-29
Section IV: Range Test pass criteria
Range Test measures Zigbee RF quality using two metrics. Received Signal Strength
Indicator (RSSI) and Packet Error Rate (PER). The Transmitter (TX) in each Zigbee device
has an ability to transmit RF power at +19dBm or 79mW in North America and +8dBm or
6.3mW in Europe. All devices have a Receiver (RX) sensitivity of -102dBm.
The total RF budget is the difference in TX power and RX sensitivity.
RF signals attenuate as one goes further from the TX location or if there are any kind of
obstruction between the TX and RX. Besides distance and obstructions, there are other
sources of errors that affect RF link quality. This includes noise and interference from any
transmitter that is emitting RF power close to the same frequency band, people walking by
or obstructing objects such as cars, environmental conditions, as well as multipath effects.
To account for these sources of errors, the Range Test pass/fail criteria is more stringent
than implied by the RX sensitivity of -102dBm. The table below shows the criteria used for
passing/failing Range Test.
Section V: Selecting the right Range Extender
Range extension is recommended whenever the Range Test fails. It is very important to
select the right Range Extender based on the results of Range Test and specific details of
location of equipment at a site. Enphase has considered two types of range extension.
Zigbee Wireless Range Extender (ZWRE)
Wired USB Extender (WUE)
The ZWRE works as a repeater and provides a path for a “hop” between the equipment.
Since the “hop” can reduce the effective distance between Zigbee nodes by a factor of
2, ZWRE can be expected to have a theoretical RSSI improvement of ~6dBm. More than
one ZWREs is not recommended as there is diminishing return in tradeoff between RSSI
improvement and increase in latency.
ITK DISPL AY
RSSI THRESHOLD
PER THRESHOLD
RANGE TEST PASS/FAIL
Excellent
-50dBm
1%
Pass
Strong
-55dBm
2%
Pass
Average
-60dBm
3%
Pass
Weak
-65dBm
4%
Fail
Unacceptable
< -65dBM
> 4%
Fail
