Lesson 2/Learning Event 5
(j) Digital services (category 10). This category was designed to
set standards for channels and circuits routed over digital transmission
facilities, Pulse Code Modulation (PCM) and Time Division Multiplex (TDM)
equipments. This type of service is more defined and explained in enclosure
8, table 1.
b. Enclosure 1, table 5 contains the cross reference between the item
number of table 1 and the parameter codes. Each type of service in table 1
is assigned an item number. When it is necessary to determine a parameter
code for a specific type of circuit/service, the item number of table 1 must
be cross-referenced with the parameter code in table 5.
EXAMPLE:
To determine the parameter code for a "nonsecure voice
circuit" (the first type of service listed in table 1).
Locate the item number for the nonsecure voice circuit in
the left column of table 1, which is 1A.
Turn to table 5 and locate 1A under the column labeled ITEM
NUMBER.
To the right of 1A in the column labeled CIRCUIT
PARAMETER CODE, is listed the parameter code for the
nonsecure voice circuit which is V1.
c. Enclosure 1, table 2 contains specific circuit parameters that
correspond to the types of services listed in table 1 for voice circuits.
This table contains the characteristics (type of test) by parameter codes.
The type of tests (frequency response, envelope delay, etc.) are listed in
the left column under characteristics. The next column contains the unit of
measurement (dB, microseconds, degree, etc.).
In the heading of the
remaining columns are listed the parameter codes for the voice circuits of
table 1.
To determine the parameters of a specific voice circuit, locate
the parameter code at the top of table 2. In the column, under the selected
parameter code will be listed the parameters for the type of test listed in
the left column.
EXAMPLE:
Determine the parameters
for
a
circuit
assigned
a
V1
parameter code.
Step 1.
Locate the V1 parameter code at the top of table
2.
Step 2.
Locate the point under the V1 column that is
parallel to the first test listed in the left
column, which is frequency response.
At that
point will be listed the parameters for frequency
response.
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