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PEB 2255
FALC-LH V1.3
Functional Description T1/J1
Data Sheet
112
2000-07
Frame alignment between system frame and receive route frame
Reporting and controlling of slips
Controlled by special signals generated by the receiver, the unipolar bit stream is
converted into bit-parallel, time slot serial data which is circularly written to the elastic
buffer using the internally generated Receive Route Clock (RCL
K
).
Reading of stored data is controlled by the System Clock sourced by SCL
K
R and the
Synchronous Pulse (S
Y
PR) in conjunction with the programmed offset values for the
receive time slot/clock slot counters. After conversion into a serial data stream, the data
is given out via port RDO. If the receive buffer is bypassed, data is clocked off with RCL
K
instead of SCL
K
R.
If
8
.1
9
2 MHz reference frequency is used, one of two channel translation modes has to
be selected. The 2
4
received time slots (T1/J1) can be translated into the 32 system time
slots (E1) in two different channel translation modes (selected by FMR1.CTM).
U
nequipped time slots are set to ‘FF
H
’. Refer to
Table 26
.
In one frame or short buffer mode the delay through the receive buffer is reduced to an
average delay of
9
6 or
48
bits. In this case S
Y
PR to be programmed as input is not
allowed. Slips are performed in all buffer modes except the bypass mode. After a slip is
detected the read pointer is adjusted to one half of the current buffer size. The following
table gives an overview of the receive buffer operating mode.
.
Table 25
Receive Buffer Operating Modes (T1/J1)
SIC1.RBS1...0
Buffer Size
TS Offset programing (RC1...0)
Slip
performance
no slips
11
bypass
1)
1)
In bypass mode the clock provided on pin SCL
K
R is ignored. Clocking is done with RCL
K
.
RFM (S
Y
PR
=
output) must be
selected
;
value of RC1...0
determines the position of RFM
RFM (S
Y
PR
=
output) must be
selected
;
value of RC1...0
determines the position of RFM
RFM (S
Y
PR
=
output) must be
selected
;
value of RC1...0
determines the position of RFM
10
short buffer
yes
01
1 frame
yes
00
2 frames
S
Y
PR is input and determines the
frame position together with
RC1...0 offset.
yes
Slips are
performed on the
frame boundary