Harris Intraplex STL-160 Series, Руководство по установке и эксплуатации

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ACS-160 Series & STL-160 Series T1 Multiplexer Installation & Operation 2 – Functional Description
Version 2.11, August 2011
2-4 Harris Corporation
Intraplex Products
2.1.3.1 Channel Multiplexing to Form T1 Aggregate
The CM-5RB common module develops midplane bus synchronization signals. The transmit section of
each channel module synchronizes to these signals and places its data onto the selected bus. The CM-
5RB module then forms the aggregate signal, using either the ESF (extended superframe) or SF (D4
superframe) framing format. ESF is the preferred format and you should use it in all cases except
when the network or CSU cannot support it. Section 2.2.1.1 –
T1 Frame Formats gives more details on
these two formats.
The CM-5RB module uses tri-state bus drivers and receivers to permit routing the multiplexer and
demultiplexer bus signals to either midplane bus (Bus A or Bus B). This versatile bus capability
enables simple multiplexer configuration for terminal or drop and insert use (Section 2.1.2 -
Drop and
Insert Operation: the Signal Bus Role ).
2.1.3.2 T1 Line Driver
Line coding can be set to either B8ZS (Bipolar with 8 Zero Substitution) or AMI (alternate mark
inversion). B8ZS is the preferred format; you should always use B8ZS, unless the network or channel
service unit cannot support it. Section 2.2.1.2 –
T1 Line Coding gives a description of these line coding
methods.
Equipment and monitor test jacks on the front of the module accept input of miniature bantam plugs.
They allow the T1 output of the multiplexer to be connected to a T1 transmission test set or to be fed
directly into the input of another multiplexer during bench testing.
The T1 line output connection is via the MA-215 module adapter. Inserting a plug into the T1
equipment out jack breaks the outgoing connection to the MA-215 module adapter. Terminating
impedance should be 100 ohms balanced. The T1 monitor out jack permits test access to the line
output without breaking the T1 line connection. Equipment connected to this jack should also provide
a 100 ohm termination impedance. The signal level at this point is approximately 20 decibels below
the line output level.
2.1.3.3 T1 Line Receiver
T1 input should be at the standard DS-1 digital cross connect level (DSX-1). T1 frame format can be
either ESF or SF. The line code can be either B8ZS (bipolar with 8-zero substitution) or AMI (alternate
mark inversion). The line receiver
● Accepts the input signal.
● Recovers receive timing.
● Decodes the bipolar signal.
A jitter buffer follows to smooth out the timing jitter usually present on an incoming signal.
The CM-5RB module receives T1 line input via the MA-215, MA-216, MA-217B, MA-235-1, or MA-235-
2 module adapter. Equipment and monitor T1 in jacks function like the T1 out jacks described
previously. All equipment connected to them should provide 100 ohms termination. The equipment in
jack breaks the connection to the T1 line input; the monitor in jack does not, but the signal level at
the monitor jack is about 20 decibels below the input level.
2.1.3.4 T1 Aggregate Demultiplexing to Individual Channels
The decoded line receive signal feeds the demultiplexer circuitry. First, the demultiplexing circuitry
achieves frame synchronization, using a proprietary robust framing algorithm that assures fast frame
acquisition and a high tolerance to errors once a frame is acquired. The average frame time for the SF
format is 4 milliseconds and for the ESF format is less than 18 milliseconds. Mean time to lose frame
in the presence of a high (10
-3
) random bit error rate exceeds several hours (Figure 2-5).