Aastra NeXspan C, Руководство по установке

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AMT/PTD/PBX/0020/2/4/EN 01/2007 Page 29
2.2.2 Functional description
The DECT base station transmits and receives radio signals to and from the mobile.
4-channel base station
The D channel of the S0 BRI transports the signal between the PBX and the base station. The
2 B channels are used to transport the ADPCM encoded 4-channel voice signals at 32 Kb/S.
DECT base stations are connected to the PBX using standard S0 interface cards with a 144 kb/s
throughput and a 2-pair cable (S0 point to point pinout).
Base station synchronization
The various base stations in a radio system are synchronized. If the synchronization is faulty or
inexistent, the "handover" function is unavailable.
DECT base stations are controlled by a common clock so that they transmit synchronous radio
signals. The clock has two transmission methods:
• synchronization by "M bit" (two pair wiring): a card declared "Master" in the system
broadcasts the clock signal to all slave cards supporting base stations. These cards then
transmit the clock signal to the base stations via the "M bit" of the S frame.
• synchronization by "third pair" or sync pair, where the clock extracted from the master base
station S0 bus is relayed to the other base stations via a specific pair linked to the two pairs
carrying the PBX signal to this base station.
If more than 4 slave base stations are connected to a master base station, a repeater must be
used to connect the slave base stations to the master base station.
The master base station must be the base station closest to the distribution frame.
It is strongly recommended to connect the master base station to the first S0 equipment declared
as DECT to cell 0. This means that its RPN is 00, which facilities its subsequent identification and
simplifies wiring checks.
Downloading to the base station
The base station is delivered from the factory with a software release already loaded. During the
initialisation of the base station, the PBX checks which software release the base station
contains. If the same release is not running on the PBX, the PBX automatically downloads its
software release to the base station.
Important: new M6241 base stations are delivered with a new software release 3.2. They are
not downloadable on previous releases. If a new M6241 base station is installed on a PBX
release earlier than R3.2, during initial installation, the base station simulates the downloading of
the PBX release but is actually inhibited. To avoid downloading base stations each time the
device is started, the PBX release is stored in the memory during initial installation.
In release 3.2 and later, the PBX software contains 2 DECT catalogues, one for the new base
station, the other for the old base station. Each catalogue contains 2 files, one for the ISDN part,
the other for the DECT part. Base station downloading is automatically managed by the PBX.
Note: Old and new base stations are compatible and work on any device (from V11.6 through
R3.2).