Nortel CS 1000 Manual page 22

22 Site planning and hardware deployment
If more than one synchronization source is present, each one forms a
separate hierarchy of DAPs called a synchronization island.
Automatic synchronization occurs within each synchronization island using
the following rules.
•
After a DAP starts, it searches for existing DAPs. If it finds one with a
lower RPN, it synchronizes with it. If no other DAP exists with a lower
RPN, the new DAP becomes the synchronization source.
•
If a DAP detects more than one other DAP, it synchronizes with the
DAP with the shortest path to the synchronization master. If two or
more DAPs have the same path length separating them from the
master, the new DAP synchronizes to the DAP with the lowest RPN.
ATTENTION
After you install SIP DECT, wait at least 15 minutes until you see the results of
the automatic synchronization.
To make a DAP a synchronization master or to give a DAP a higher
position in the synchronization structure, you can manually assign a lower
RPN number to a DAP. You can manually assign RPNs using the DAP
Manager Web interface. Automatically assigned RPNs start at 010. If you
manually assign a new RPN, ensure that it is in the range 000 to 00F.
ATTENTION
You must determine the position of the Synchronization Master before you start
site planning. Place the synchronization master, which is the DAP with the
lowest RPN, in the middle of your site, building, or buildings.
Signal strength and frame errors
Signal strength is important for DAP-handset communication (voice quality)
and synchronization between DAPs. The following items are relevant for
the signal strength for synchronization.
•
To achieve a good voice quality, the minimum signal strength at the
receiver in the handset and DAP must be --72 Decibels (referenced to
milliwatts) (dBm). This includes a margin of --10 dBm for fast fading
dips.
•
Synchronization is possible if the strength of the received signal from
another DAP is --80 dBm to --85 dBm. This is adjustable.
•
In an open area, the distance is doubled if the received signal strength
is 6 dB lower. This means that at a minimum signal strength for good
voice quality of --72 dBm and a distance X, the signal strength at the
ATTENTION
Extra DAPs can be required to establish a synchronization path.
Nortel Communication Server 1000
SIP DECT Fundamentals
NN43120-123 02.02 30 March 2010
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