Motorola MTR2000 T5544 Instruction / Field Service Manual page 207

CLN1203 Wireline Interface Board
Description of Audio/Data Signal Paths
Note
Tone Remote Control
2-wire/4-wire configurations
Figure 2.
4
For 2-wire and 4-wire configurations, phone line connections are made at
the wire-trap terminal connector on the station backplane, providing a
standard 600 Ω line matching impedance. 2-wire audio connections are
made at Line 2 Audio.
Coarse gain adjustments are provided by circuitry on the WIB for Land-
line-to-Station and Station-to-Landline audio paths. Additional fine level
adjustments are performed in software in the Station Control Module.
Model CLN1203 WIB supports tone remote control of the station. Refer to
Figure 2 for the jumper locations and correct settings for each type of re-
mote control.
2-Wire Voice Audio Path (Refer to Figure 3)
Voice audio signals sent to/from the station via 2-wire copper pair are pro-
cessed by the 2-wire audio circuit on the WIB (Line 2 Audio). The audio
transformer in this circuit may have both inbound and outbound audio
signals present simultaneously. In this case, the outbound and inbound
signals are mixed and routed via the inbound audio path to the SCM,
where an adaptive cancellation routine in the DSP isolates the inbound au-
dio. The 2-wire audio circuit operates as follows:
Landline-to-Station balanced audio is input to the primary of an audio
transformer (input has standard 600 Ω line matching impedance). The sig-
nal is induced into the transformer secondary and fed to a buffer.
The buffer sums the inbound and outbound signals and feeds this signal,
via an analog switch (not shown), to pre-emphasis and gain adjust circuit-
ry. To compensate for line losses, the gain adjust circuitry provides coarse
P10, P12, P14, P16,
P11 P13 P15 P17
out
CLN1203 Wireline Interface Board Jumpers Settings
P2
T1
C15
P11
P10
C74
P15 P14
C84
P13
P12
P17
P16
T2
P6
68P81096E29-F
09/30/05