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4 Software Operation MIX 56 User Manual
4-46 Telect, Inc. 122188-10 A0
PERFORMING DIAGNOSTICS
Running Loopbacks
ALERT
!
ALERT! When a loopback is running, the low-speed channel or
high-speed circuit on which it is running is out of service.
The following loopbacks can be set from the Loopbacks screen:
Low Speed “Line”: The signal is sent through the DS1 LIU (Line Inter-
face Unit) and looped back before reaching the Encoder/Decoder. The DS1
Received signal is looped back out as the DS1 Transmitted signal.
Low Speed “Local”: The demultiplexed DS1 signal from the M13 MUX
is encoded and sent to the DS1 LIU Equalizer, where it is looped back
through the DS1 LIU Decoder, and then multiplexed and added to the DS3
stream by the M13 MUX.
High Speed “Line DS3”: The received signal is sent through the DS3 LIU
and through the M13 MUX Decoder, where it is looped back through the
Encoder and put onto the DS3 stream. The DS3 Received signal is looped
back out as the DS3 Transmitted signal.
High Speed “Local DS3”: The signal is sent through the DS1 LIUs, multi-
plexed, and looped back before reaching the M13 MUX Encoder.
High Speed “Line, DS1 Ch xx in DS3”: The signal path is the same as the
“Line, DS3” loopback, but instead of the entire DS3 signal being looped
back, an individual DS1 channel of the Muxed DS3 signal is looped back.
The illustration below shows the path of each loopback.
Line
Driver
Pulse
Shaper
Jitter
Attenuator
Encoder
DS3 LIU
M13 MUX DS1 LIU
Low-Speed Local
Low-Speed Line
High-Speed Local
High-Speed Line
MIX 56 Loopback Options
Equalizer
Peak
Detector
Clock &
Date
Recovery
Decoder
Tributary
Mapper
DS3
Framer &
M32
Demux
M12 Mux
& DS2
Framer
M23 Mux
& DS3
Framer
Decoder
Encoder
DS2
Framer &
M21
Demux
Tributary
Interface
Tributary
Mapper
Tributary
Interface
Equalizer
Noise
Crosstalk
Filter
Clock &
Data
Recovery
Pulse
Shaper
Line
Driver