AVT MAGIC ISDN, Описание аппаратуры

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PA G E 2 5
S Y S T E M D E S C R I P T I O N
Network interfaces
The following network interfaces are available:
– 1
×
X.21, n
×
64-kbit/s to 1920-kbit/s
– 3
×
So (ISDN)
Data interfaces
The MAGIC ISDN Audio codec has two different data interfaces available for
the transmission of additional data. All interfaces are implemented as DCEs.
– HSD for High Speed Data, 64 kBit/s
– LSD for Low Speed Data between 300 and 38400 Baud.
Operator interfaces
The following four operator interfaces are available for the control of the MA-
GIC ISDN Audio Codec:
– User I/O
– RS.232C
– RS232-AUX (on request)
– RS 485 (on request)
FIGURE 2.6 shows the block diagram of the interface unit. The main elements
are the
,2TQ\GUUQT
and the
&GOWZ &52
The J.52 DSP handles the implimen-
tation of the J.52 as well as control of the complete system. The Demux signal
processor handles the complete data multiplexing including the delay com-
pensation for ISDN connections.
To retain the maximum flexibility, extensive use is made of
2TQITCOOCDNG .QIKE
EQORQPGPVU
The
2..
Block
RTQXKFGU VJG KORQTVCPV ENQEMU UWEJ CU VJG
48-kHz sampling clock for
the Audio Codec and the different clocks that are necessary for X.21 opera-
tion.
The
#WFKQ &52
provides the coding according to the ITU-T-Standards G.711,
G.722 and G.728. Based on the use of an individual
#&&# %QPXGTVGT
the Com-
mand channel can operate in parallel with the ISO/MPEG Layer II/III Audio
Codec.
The
&1
block generates the control signal for the
1RGTCVQT
block. in this
block, exactly as in the
.KPG &CVC
and
'ZVGPUKQP $W
s blocks, the necessary inter-
face adaptations are implimented. The only exception to be noted is the
.KPG
$NQEM
. In this block an individual processor is incorporated to handle the access
of up to six ISDN B channels. Here however, only the evaluation of the D chan-
nel protocol is carried out. The actual user data is routed via the programma-
ble logic to the signal processor for processing.