11
LDM-144LR
An RS-422/V.36 terminal can be connected through the RS-530 interface
using an adaptive cable, as detailed in
Appendix B
.
The LDM-144LR incorporates a built-in Bit Error Rate Tester (BERT). The
internal BERT enables complete testing of both modems and the line without
external test equipment. A CCITT/V.52, 511-bit pseudo-random test pattern
is generated through a front-panel switch for testing end-to-end connectivity.
When a bit error is encountered, the ERR indicator flashes.
2.2 Physical Description
The LDM-144LR is available as a standalone unit (LDM-144LR), or as a rack-
mounted unit (LDM-144LR Card) within a 19" rack. A 19" rack can carry up
to 14 cards and provides DB25 connectivity to digital interfaces. Optional
V.35 and X.21 interface adapters are available.
2.3 Functional Description
This section contains the functional descriptions of the LDM-144LR circuit
blocks, primarily those circuits that are required to set the correct
configuration of the modem. For the block diagram, see
Figure 2-1.
