User's Manual Part 1

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5.7.9 Aligning the ODUs
The following is a description of the steps taken to establish a radio link between the two
units
forming the bridge and align the units for the best signal strength.
OS-Gemini uses audible tones during installation to assist the installer with alignment. The
tones and their meanings are as follows:
State Name Tone
Description
State Description Pitch
Indication
(Higher pitch =
higher power)
Band Scan Regular beep Executing band scan N/A
Scanning Slow broken
tone
Not demodulating the wanted signal Rx Power
Synchronised Fast broken tone Demodulating the wanted signal Rx Power
Registered Solid tone Both Master and Slave units
exchanging Radio layer MAC
management messages
Rx Power
Table 4 Audio indications from the ODU
The term ‘wanted signal’ refers to that of the peer unit being installed.
In each of the states detailed above the unit should be aligned to give the highest pitch tone. It
should be noted that if, when in the Synchronised or Registered state the tone varies wildly,
you may be suffering from interference or a fast fading link. Installing in this situation may not
give a reliable link. The cause of the problem should be investigated.
For the ease of alignment both Master and Slave units use the install tones in the same way
but with some small behavioural differences. This allows the installer to install the Slave unit
first and carry out the initial alignment with the Master unit if desired. However due to the
Behavioural differences of Master and Slave units it is recommended that the Master unit is
installed first and the initial alignment carried out at the Slave unit.
The following behaviour should be noted:
When first started up and from time to time the Master unit will carry out a band scan to
determine which channels are not in use. During this time, between 10 and 15 seconds, the
Master unit will not transmit and as a consequence of this neither will the Slave unit. During this
time the installation tone on the master unit will drop back to the band scan state and the Slave
unit will drop back to Scanning state with the pitch of the tone set be the background noise
level. Alignment of the unit should cease during this time.