Bt8370/8375/8376
2.0 Circuit Description
2.4 Receiver
Fully Integrated T1/E1 Framer and Line Interface
2.4.5.3 Analog Loss of
Signal
Receive Analog Loss of Signal (RALOS) is declared in analog receive mode,
[RDIGI = 0; addr 020], when RTIP/RRING input signal amplitude is less than the
programmed (VGA_MAX) threshold. In the digital receive mode, RDIGI = 1,
RALOS is declared when the Receive Clock Input (RCKI) remains low for
125 µs. RALOS real-time status is available in ALM1; RALOS interrupt is
available in ISR7.
2.4.5.4 Alarm Indication
Signal
If the line rate is T1 [T1/E1N; addr 001], the criteria for Receive Alarm Indication
Signal (RAIS) is the reception of 4 or fewer 0s in a period of 3 ms (4632 bits), and
the assertion of RLOF. If the line rate is E1, RAIS is set when 2 consecutive
double frames each contain 2 or fewer 0s out of 512 bits and FAS alignment is
lost [FRED; addr 049]. RAIS real-time status is available in ALM1; RAIS
interrupt is available in ISR7.
2.4.5.5 Yellow Alarm
The criteria for Yellow Alarm (YEL) is described in Table 3-13, Receive Yellow
Alarm Set/Clear Criteria. YEL real-time status is available in ALM1; YEL
interrupt is available in ISR7.
2.4.5.6 Multiframe YEL
The criteria for Multiframe Yellow Alarm is described in Table 3-13, Receive
Yellow Alarm Set/Clear Criteria. MYEL real-time status is available in ALM1;
MYEL interrupt is available in ISR7.
2.4.5.7 Severely Errored
Frame
A SEF is reported when the receive signal does not meet the requirements of
ANSI T1.231. SEF real-time status is available in ALM3. A 2-bit counter is also
available [SEF; addr 05A]. An interrupt is available in ISR4 to indicate that the
SEF counter overflowed.
2.4.5.8 Change of
Frame
Each COFA increments a 2-bit counter [COFA; addr 05A]. An interrupt is
available in ISR4 to indicate that the COFA counter overflowed.
Alignment
2.4.5.9 Receive
Multiframe AIS
Receive Multiframe AIS (RMAIS) is reported when the receive TS16 signal
contains 3 or fewer 0s out of 128 bits in each multiframe over 2 consecutive
multiframes according to the requirements of ITU–T Recommendation G.775.
RMAIS is checked only in E1 CAS mode. RMAIS real-time status is available in
ALM3 [addr 049].
N8370DSE
Conexant
2-19
CONEXANT [ CONEXANT SYSTEMS, INC ]
