QuadFALC
TM
PEF 22554 E
Functional Description E1/T1/J1
Data Sheet
104
Rev. 1.2, 2006-01-26
The function of B7ZCS in the transmit direction can be selectively defeated on a channel by channel basis by using
the QuadFALC
TMs clear channel capability. Registers CCB(3:1) are used to disable B7ZCS and insertion of
robbed bit signaling.
3.5.1
Bipolar Violation Detection
If the register bit BFR_E.BPV is set to 0 and after execution of the sequence described below, Bipolar Violations
(BPV) consisting on single 1 pulses (separated from the previous 1 pulse by at least one 0 pulse) or on two
consecutive 1 pulses are detected correctly and thus counted by the bipolar violation counter. Bipolar Violations
(BPV) consisting on more than two consecutive 1 pulses are not detected correctly and thus not counted by the
bipolar violation counter.
Compatibel to the QuadFALC V2.1, Bipolar Violations (BPV) are not detected correctly and thus not counted by
the bipolar violation counter, if BFR_E.BPV is set to 1 (default after reset).
If the second of two consecutively received Alternate Mark Inversion (AMI) pulses is a BPV (second pulse has the
same polarity as the first pulse) and BFR_E.BPV is set to 1, the receiver converts the second AMI pulse to a
logic zero. This conversion will cause a bit error and will mask detection and counting of the BPV. In contrast, any
BPV separated from the previous 1 pulse by at least one 0 pulse is detected, counted, and recorded correctly
This BPV conversion is not expected to cause any system level problems. BPV counts, bit errors counts, and CRC
counts may be slightly inaccurate, depending on the BPV rate. Note that the special B8ZS and HDB3 substitution
do not contain consecutive BPV pulses so the conversion described above will not occur when receiving these
patterns
The behaviour of the Bipolar Violation Detection is illustrated in Figure 23.
Figure 23
Behaviour of Bipolar Violation Detection
Independent from the setting of BFR_E.BPV all BPVs will be detected
In patterns with alternate 1 and 0 (50 % 1 density)
In all fixed patterns with no consecutive 1 (less than 50 % 1 density)
For BFR_E.BPV = 1 and execution of the sequence described below, variable or fixed patterns with at least two
consecutive 1 pulses will show reduced BPVs. Reduction of BPVs depends on densitiy of 1 pulses. As 1 pulse
density increases, BPV rate decrease until the limiting case of “all-one”. In framed “all-one” pattern no BPVs will
be detected, except a BPV following a frameing bit that is 0.
BPV
+1
0
0 -1
0 +1 -1 +10 +10-1 +1 -1 -1
0 +1
P
N for
BFR.BPV
= 1
Data bits set to 0,
BPV not detected
RL1
RL2
Internal Signals:
BPV always
detected
BPV detected if
BFR.BPV = 0
N for
BFR.BPV
= 0
BPV for
BFR.BPV
= 1
BPV detected if
BFR.BPV = 0
BPV not
detected
BPV for
BFR.BPV
= 0
-1