Bt8370/8375/8376
3.12 Transmitter Registers
Fully Integrated T1/E1 Framer and Line Interface
Table 3-18. Criteria for T1 Loss/Recovery of Transmit Frame Alignment
Mode
FT Only
Description
Terminal Frame Alignment is recovered when
One, and only 1 valid Ft pattern (1010) is found in 12 alternate F-bit locations (3 ms), when F-bits are
separated by 193 bits.
Transmit Loss of Frame (TLOF) alignment is declared when
Number of Ft bit errors detected meets selected loss of frame criteria [TLOFA–TLOFC; addr 071].
SF
Superframe alignment is recovered when
•
•
Terminal frame alignment is recovered, identifying Ft bits.
Depends on SF submode.
With JYEL:
If SF pattern (00111x) found in Fs bits.
If no JYEL:
SF pattern (001110) found in Fs bits.
Fs errors do not cause Transmit Loss of Frame (TLOF) alignment.
Transmit loss of frame alignment (TLOF) declared when
The number of Ft bit errors detected meets the selected reframe criteria [TLOFA–TLOFC; addr 071].
NOTE(S): Fs bit multiframe errors are reported in TMERR [ISR0; addr 00B], but do not cause a loss of
transmit frame alignment.
SLC
Superframe alignment is recovered when
•
•
Terminal frame alignment is recovered, identifying Ft bits.
The SLC pattern (refer to Table A-3, SLC-96 Fs Bit Contents) is found in 16 of 32 Fs bits according to
Bellcore TR-TSY-000008.
Fs errors do not cause Transmit Loss of Frame (TLOF) alignment.
Transmit loss of frame alignment (TLOF) declared when
The number of Ft bit errors detected meets the selected reframe criteria [TLOFA–TLOFC; addr 071].
NOTE(S): Fs bit multiframe errors are reported in TMERR [ISR0; addr 00B], but do not cause a loss of
transmit frame alignment.
ESF
Extended superframe alignment is recovered when
A valid FPS candidate is located (001011). Candidate bits are separated by 772 digits and are received
without pattern errors.
•
If only 1 valid FPS candidate and
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.
If two or more valid FPS candidates and:
•
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.
Transmit loss of frame alignment (TLOF) declared when
The number of FPS pattern errors detected meets the selected loss of frame criteria
[TLOFA–TLOFC; addr 071].
3-70
Conexant
N8370DSE
CONEXANT [ CONEXANT SYSTEMS, INC ]
