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Data Sheet
141
Rev. 1.2, 2006-01-26
QuadFALC
TM
PEF 22554 E
Functional Description E1
4.4.2.1
Transmit Transparent Modes (E1)
In transmit direction, contents of time slot 0 frame alignment signal of the outgoing PCM frame are normally
generated by the QuadFALC
TM. However, transparency for the complete time slot 0 can be achieved by selecting
the transparent mode XSP.TT0. With the Transparent Service Word Mask register TSWM the S
i-bits, A-bit and
the S
a-bits can be selectively switched through transparently.
4.4.2.2
Synchronization Procedure (E1)
Synchronization status is reported by bit FRS0.LFA. Framing errors are counted by the Framing Error Counter
(FEC). Asynchronous state is reached after detecting 3 or 4 consecutive incorrect FAS words or 3 or 4 consecutive
incorrect service words (bit 2 = 0 in time slot 0 of every other frame not containing the frame alignment word), the
selection is done by bit RC0.ASY4. Additionally, the service word condition can be disabled. When the framer lost
its synchronization an interrupt status bit ISR2.LFA is generated.
In asynchronous state, counting of framing errors and detection of remote alarm is stopped. AIS is automatically
sent to the backplane interface (can be disabled by bit FMR2.DAIS).
Further on the updating of the registers RSW, RSP, RSA(8:4), RSA6S and RS(16:1) is halted (remote alarm
indication, S
a/Si-Bit access).
The resynchronization procedure starts automatically after reaching the asynchronous state. Additionally, it can
be invoked user controlled by bit FMR0.FRS (force resynchronization, the FAS word detection is interrupted until
the framer is in the asynchronous state. After that, resynchronization starts automatically).
Synchronous state is established after detecting:
A correct FAS word in frame n,
The presence of the correct service word (bit 2 = 1) in frame n + 1,
A correct FAS word in frame n + 2.
Frame not Containing the Frame
Alignment Signal or
Service Word
S
i
1A
S
a4
S
a5
S
a6
S
a7
S
a8
1)
2)
3)
4)
1) S
i-bits: reserved for international use. If not used, these bits should be fixed to 1B. Access to received information trough
bits RSW.RSI and RSP.RSIF. Transmission is enabled by bits XSW.XSIS and XSP.XSIF.
2) Fixed to 1
B. Used for synchronization.
3) Remote alarm indication: In undisturbed operation 0; in alarm condition 1
B.
4) S
a-bits: Reserved for national use. If not used, they should be fixed at 1B. Access to received information trough bits
RSW.RY0…4. Transmission is enabled by bits XSW.XY0…4. HDLC signaling in bits S
a4 to 8 is selectable. As a special
extension for double frame format, the S
a-bit registers RSA4 to 8/XSA4 to 8 can be used optionally.
Table 37
Transmit Transparent Mode (Doubleframe E1)
Transmit Transparent Source for
Enabled by
Framing
A-Bit
S
a-Bits
S
i-Bits
– XSP.TT0
TSWM.TSIF
TSWM.TSIS
TSWM.TRA
TSWM.TSA(8:4)
(int. gen.) via pin
XDI
1)(int. gen.)
(int. gen.) (int.
gen.) (int. gen.)
1) Pin XDI or XSIG or XFIFO buffer (signaling controller)
XSW.XRA
2)via
pin XDI
XSW.XRA
XSW.XRA via
pin XDI
XSW.XRA
2) Additionally, automatic transmission of the A-bit is selectable.
XSW.XY0…4
3)via
pin XDI
XSW.XY0…4
XSW.XY0…4 via
pin XDI
3) As a special extension for double frame format, the S
a-bit register can be used optionally.
XSW.XSIS, XSP.XSIF via pin
XDI via pin XDI via pin XDI
XSW.XSIS, XSP.XSIF
Table 36
Allocation of Bits 1 to 8 of Time Slot 0 (E1) (cont’d)
Bit Alternate Number Frames
1
2
3
4
5
6
7
8