BT8375 CONEXANT [Conexant Systems, Inc], BT8375 Datasheet - Page 52

• Manufacturer Part Number: BT8375
• Description: single chip transceivers for T1/E1 and Integrated Service Digital Network (ISDN) primary rate interfaces
• Manufacturer: CONEXANT [Conexant Systems, Inc]

2.0 Circuit Description
2.4 Receiver
Table 2-3. Criteria for Loss/Recovery of Receive Framer Alignment (2 of 2)
2-24
SF
SLC
FSLOF
ESF
T1DM
Mode
Superframe alignment is recovered when terminal frame alignment is recovered, identifying Ft bits.
Depends on SF submode: if JYEL, only Ft bits are used; Fs bits are ignored. If no JYEL, SF pattern (001110) found
in Fs bits.
During any SF mode, loss of frame alignment (FRED) is declared when the number of frame errors detected, either
Ft or Fs bit errors, meets selected loss of frame criteria [RLOFA–RLOFC; addr 040]. FS_NFAS [addr 045]
determines whether Fs bits are included in error count.
Superframe alignment is recovered when
During SLC modes without FSLOF, loss of frame alignment (FRED) is declared when the number of Ft bit errors
detected meets selected reframe criteria [RLOFA–RLOFC; addr 040].
FSLOF instructs the online framer to monitor 16 of 36 Fs bits (SLC multiframe pattern) for loss of frame alignment
criteria. FS_NFAS [addr 045] must also be set to include Fs bits in loss of frame. FSLOF does not affect the offline
framer's search criteria.
Extended Superframe alignment is recovered when
without pattern errors.
If there is only 1 valid FPS candidate and the mode is 1 of the following:
If there are two or more valid FPS candidates and the mode is 1 of the following:
During any ESF mode, loss of frame alignment (FRED) is declared when:
During T1DM mode, frame alignment is recovered in two steps:
1. A 6-bit T1DM pattern (10111xx0) is found.
2. A valid F-bit pattern (Ft, Fs, or FPS) is found in the first six consecutive frames of the 12-frame cycle aligned to
During T1DM mode, loss of frame alignment (FRED) is declared when the number of frame errors detected, either
Ft, Fs, or T1DM errors, meets selected loss of frame criteria [RLOFA–RLOFC; addr 040].
Fs_NFAS; addr 046] does not affect T1DM mode.
NOTE(S):
reframe criteria, and FS_NFAS inactive.
A valid FPS candidate is located (001011). Candidate bits are each separated by 772 digits and are received
No CRC mode—align to FPS, regardless of CRC6 comparison.
Mimic CRC mode—align to FPS, regardless of CRC6 comparison.
Force CRC mode—align to FPS, only if CRC6 is correct.
No CRC mode—do not align (INVALID status).
Mimic CRC mode—align to first FPS with correct CRC6.
Force CRC mode—align to first FPS with correct CRC6.
Number of FPS pattern errors detected meets selected loss of frame criteria [RLOFA–RLOFC; addr 040].
the T1DM pattern.
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Terminal frame alignment is recovered, identifying Ft bits.
SLC pattern (refer to
TR-TSY-000008 .
To meet Bellcore TA-TSY-000278, the processor must select SF + T1DM framer mode, RLOFC (2 of 6)
Table A-3, SLC-96 Fs Bit Contents
Conexant
Description
Fully Integrated T1/E1 Framer and Line Interface
) is found in 16 of 36 Fs bits, according to Bellcore
Bt8370/8375/8376
N8370DSE