Advance Information MT88E46
CPE goes off-hook
CPE mutes handset, disables keypad
CPE unmutes handset
and enables keypad
and performs MEI check (See TIA/EIA-777)
CPE sends
TIP/RING
Speech
G
Mark
E
Data
CAS
ACK
C
A
B
D
F
Note 5
PWDN
25ms
Note 1
(Note 6)
30-40ms
Off Hook CASen
(Note 6)
FSKen
Note 2
Note 3
Note 4
(Note 6)
t
PU
OSC2
t
DET2
DET
(Note 7)
t
t
t
CA
DW
CP
CD
A = 75-85ms
B = 0-100ms
C = 55-65ms
D = 0-500ms
E = 58-75ms
F = feature specific
G ≤ 50ms
DR
(Note 7)
DCLK
DATA
Data
Figure 17 - Application Timing: Bellcore Off-Hook Data Transmission, e.g. CIDCW
Notes:
1)In a CPE where AC power is not available, the designer may choose to switch over to line power when the CPE goes off-hook and
use battery power while on-hook. The CPE must also be CID (on-hook) capable because a CIDCW CPE includes CID functionality.
2)Non-FSK signals such as CAS, speech and DTMF tones are in the same frequency band as FSK. They will be demodulated and give
false data. Therefore the MT88E46 should be taken out of FSK mode when FSK is not expected.
3)If the CPE is the ACK-Sender, the MT88E46 may be put into FSK mode right after ACK has been sent. If the CPE is not the ACK-
Sender, the MT88E46 should be put into FSK mode at 30ms (min ACK delay) + 55ms (min ACK duration) = 85ms after the line
HIGH transition. In that case the FSK carrier detector may be activated by the ACK if both the ACK delay and the ACK duration are
at maximum. TR-NWT-000575 specifies that ACK = DTMF ‘D’ for non-ADSI CPE, ‘A’ for ADSI CPE.
4)The MT88E46 should be taken out of FSK mode when CD has become inactive, or when more than 5 framing errors have been
detected in the message, or when more than 150ms of continuous Mark or Space has been detected.
5)In an unsuccessful attempt where the central office does not send the FSK signal, the CPE should unmute the handset and enable
the keypad after interval D has expired.
6)PWDN, Off Hook CASen and FSKen are internal signals decoded from CB0/1/2.
7)The DR/DET output pin is the DET signal when CAS detection is selected, the DR signal when FSK is selected.
21
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
