4RF Aprisa XE, Руководство пользователя

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In-service commissioning | 169
Synchronizing the terminals
After you have completed the alignment of the two antennas, you must ensure the two terminals are
synchronized.
The terminals are synchronized when:
ƒ the OK LED is green, which indicates that no system alarms are present, and
ƒ
the RX LED is green, which indicates a good signal with no errors, and
ƒ the TX LED is green, which indicates that there are no transmitter fault conditions.
Checking performance
The amount of testing performed on the completed installation will depend on circumstances. Some
customers may need to prove to a local licensing regulatory body that the link complies with the
license provisions. This may require special telecommunications test equipment to complete these
tests. Most customers simply want to confirm that their data traffic is successfully passing over the link,
or that the customer interfaces comply with known quality standard.
However, the most important performance verification checks are:
ƒ Receive input level
ƒ Fade margin
ƒ Long-term BER
Checking the receive input level
The received signal strength at the local terminal is affected by many components in the system and
has a direct relationship with the resulting performance of the link. A link operating with a lower than
expected signal strength is more likely to suffer from degraded performance during fading conditions.
The receive input level of a link is normally symmetrical (that is, similar at both ends).
1. Compare the final RSSI figure obtained after antenna alignment with that calculated for the link.
2.
If the RSSI figure is in excess of 3 dB down on the predicted level, recheck and correct problems
using the table below and then recheck the RSSI. Alternatively, recheck the link budget
calculations.
Possible cause Terminal(s)
Is the terminal operating on the correct frequency? Local & remote
Is the remote terminal transmit power correct? Remote
Are all the coaxial connectors tight? Local & remote
Is the antenna the correct type, that is, gain and frequency of operation? Local & remote
Is the antenna polarized? Local & remote
Is the antenna aligned? Local & remote
Is the path between the terminals obstructed?
Note: If following the above steps does not resolve the situation, contact Customer Support for
assistance.
3.
Record the RSSI figure on the commissioning form.
4. Repeat steps 1 to 2 for the other end of the link.