
PEB 22554
Functional Description T1 / J1
Semiconductor Group
247
09.98
7.7
Framer Operating Modes T1 / J1
General
Activated with bit FMR1.PMOD = 1.
PCM line bit rate
Single frame length
Framing frequency
Organization
:
:
:
:
1.544 MBit/s
193 bit, No. 1 … 193
8 kHz
24 time-slots, No. 1 … 24
with 8 bits each, No. 1 … 8 and one preceding F bit
Selection of one of the four permissible framing formats is performed by bits
FMR4.FM1/0 . These formats are:
F4
:
4-frame multiframe
F12
:
12-frame multiframe (D4)
ESF
:
Extended Superframe
F72
:
72-frame multiframe (SLC96)
The operating mode of the QuadFALC is selected by programming the carrier data rate
and characteristics, line code, multiframe structure, and signaling scheme.
The QuadFALC implements all of the standard and/or common framing structures PCM
24 (T1, 1.544 MBit/s) carriers. The internal HDLC-Controller supports all signaling
procedures including signaling frame synchronization / synthesis in all framing formats.
After RESET, the QuadFALC must be programmed with FMR1.PMOD = 1 to enable the
T1(PCM24) mode. Switching between the framing formats is done via bit FMR4.FM1/0
for the receiver and for the transmitter.
General Aspects of Synchronization
Synchronization status is reported via bit FRS0.LFA (Loss Of Frame Alignment).
Framing errors (pulse frame and multiframe) are counted by the Framing Error Counter
FEC.
Asynchronous state is reached if
2 out of 4 (bit FMR4.SSC1/0 = 00), or
2 out of 5 (bit FMR4.SSC1/0 = 01), or
2 out of 6 (bit FMR4.SSC1/0 = 10), or
4 consecutive multiframe pattern in ESF format are incorrect
(bit FMR4.SSC1/0 = 11)
.
framing bits (terminal framing or multiframing) are incorrect. If auto-mode is enabled,
counting of framing errors is interrupted.
The resynchronization procedure may be controlled by either one of the following
procedure: