CLN1205 Wireline Interface Board
68P81096E31-B
5
09/20/05
Description of Audio/Data Signal Paths
8-Wire Voice Audio Data Path
(Refer to Figure 2, Lines 1 to 4)
For this 8-wire configuration:
-
phone line1 and line2 connections are made at the wire-trap terminal
connector on the station backplane, providing a standard 600
Ω
line
matching impedance.
-
line3 and line4 connections are made at the system connector on the
station backplane, providing a standard 600
Ω
line matching imped-
ance.
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 within the Station Control Module.
8-wire operation is provided through two sets of circuitry; each set pro-
vides a 4-wire voice audio data path.
4-Wire Voice Audio Data Path
(Refer to Figure 2, Lines 1 and 2)
For 4-wire configurations, phone line1 and line2 connections are made at
the wire-trap terminal connector on the station backplane. Landline-to-
Station signals are connected at Line 1 Audio. Station-to-Landline signals
are connected at Line 2 Audio.
Voice audio signals sent to/from the station via 4-wire copper pair are pro-
cessed by the 4-wire audio path on the WIB (Line 1 Audio & Line 2 Audio).
The 4-wire audio path operates as follows:
Landline-to-Station balanced audio (Line 1 Audio) is input to the primary
of an audio transformer (input has standard 600
Ω
line matching imped-
ance). The signal is induced into the transformer secondary and fed to a
buffer.
Station-to-Landline audio is input to the WIB as PCM data (WL 1/2 RXD)
and fed to a D/A converter in the PCM codec, which takes the PCM data
and converts it to an analog audio signal. The audio signal is fed to the
gain adjust circuitry. Under control of the SCM (via the SPI latch), the gain
adjust circuitry provides four coarse levels of gain adjustment (0dB, -6dB,
-12dB, and -20dB). The output of the gain adjust circuitry is fed through
a 2-pole low-pass filter and into the inputs of two amplifiers (line drivers).
The outputs of the amplifiers are fed to two transistors which are connect-
ed in a push-pull configuration to drive the primary of an audio trans-
Note
Note
Summary of Contents for MTR2000 T5544
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Page 160: ...VHF Receiver Module 6 68P81096E19 B 09 30 05 THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 167: ...VHF Exciter Module 6 68P81096E22 C 09 30 05 THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 259: ...DLN6622 500W Power Supply Module 6 68P81011Y31 O 03 10 06 THIS PAGE INTENTIONALLY LEFT BLANK ...
Page 271: ...DLN6624 250W Power Supply Module 6 68P81011Y29 O 03 10 06 THIS PAGE INTENTIONALLY LEFT BLANK ...