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DDS SYSTEM INTERFACE
Connection between the DDS/MR64 and the DDS system consists of
four leads divided to form a receive data pair and a transmit data pair.
The leads are on a miniature 8-position jack (RJ48) without a shorting
bar as shown in FCC Rules and Regulations Part 68, Subpart F, Figures
68.500(d)(1) and (d)(2). The remaining pins are not used. A mating
connector is mounted on the DDS/MR64.
The sense levels, voltage levels, and impedances of these interface lines
conform to AT&T Technical Reference Pub 62310. Pin assignments are
listed in Table 3-4.
Table 3-4. Pin Assignments
Function
Transmit Tip (T1)
Transmit Ring (R1) DDS/MR64 to line
Receive Ring (R)
Receive Tip (T)
The receiver incorporates an automatic line equalizer to compensate for
any length DDS line.
SEALING CURRENT
When the DDS/MR64 is used as a Limited Distance Modem, the DDS/
MR64 has the ability to source sealing current. A dip switch (Figure 3-
1) on the stand alone unit PC board or the auxiliary jack along with the
dip switch on the shelf mount unit provides this service. Do not use this
switch or connect this jack if the unit is operating over the DDS
network. This option should only be used at one end of an LDM-type
circuit.
Dip Switch
1
2
OFF
OFF
ON
ON
Direction
DDS/MR64 to line
Line to DDS/MR64
Line to DDS/MR64
3
4
ON
ON
OFF
OFF
DDS/MR64
Line Pin
Number
2 and 5
1 and 4
8 and 6
7 and 3
Mode
Normal DDS operation
Source sealing current
Operation
UDS Wire
Color
Orange
Blue
Slate
Brown
3-7
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