4RF Aprisa XE, Руководство пользователя

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In-service commissioning | 171
7.
Record the fade margin and SNR results on the commissioning form.
Note: If the transmit power is reduced using SuperVisor rather than an external attenuator, the
fade margin should be recorded as “Greater than x dB” (where x = the power reduction).
8.
Restore the remote terminal transmit power to normal.
9. Repeat steps 1 to 7 for the other end of the link.
Note: If following all the guidelines above does not resolve the situation, contact Customer
Support for assistance.
Checking long-term BER
The BER test is a measure of the stability of the complete link. The BER results of a link can be
asymmetrical (that is, different at each end).
1.
Select Link > Performance > Summary and check the current BER and error counters of the link.
(If necessary, clear out any extraneous errors by selecting Reset Counters).
2. Wait 15 minutes, and check the BER display and error counters again. If there are a small number
of errors and the BER is still better than 10
-9
, continue the test for 24 hours. If there are a
significant number of errors, rectify the cause before completing the 24 hour test.
Note: It is normal to conduct the BER test in both directions at the same time, and it is important
that no further work be carried out on the equipment (including the antenna) during this period.
3. The BER after the 24 hour test should typically be better than 10
-8
.
4.
Record the BER results on the commissioning form.
Bit Error Rate tests
A Bit Error Rate (BER) test can be conducted on the bench, (see “Bench setup” on page 37).
Attach the BER tester to the interface port(s) of one terminal, and either another BER tester or a
loopback plug to the corresponding interface port of the other terminal.
This BER test can be carried out over the Ethernet, E1/T1, V.24 or HSS interfaces. It will test the link
quality with regard to user payload data.
Caution: Do not apply signals greater than -20 dBm to the antenna as they can damage the receiver.
In a bench setup, there must be 60 - 80 dB at up to 2 GHz of 50 ohm coaxial attenuation (capable of
handling the transmit power) between the terminals’ antenna connectors.