CTI Products EXB-232 Asynchronous Serial System Extender - Manual (Page 29)

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Appendix D Application Notes
Using the EXB-TELCO Module with Motorola STARPLEX Microwave System
This application note describes how Motorola’s STARPLEX microwave system can be used to
extend the range of an MCN network. The two MCN networks are connected to the STARPLEX
system using a pair of MCN Extender (EXB) Modules as shown in the diagram below.
CA-80329-100
EXB
TX
RX
RX
13dB PAD
TX
1OdB PAD
RX
TX
-16dBm
-16dBm
-26dBm
-3dBm
4-WIRE
TERMINATION
CARD MODEM
EXB
TX
RX RX
TX
MODEM
RX
13dB PAD
TX
1OdB PAD
4-WIRE
TERMINATION
CARD
-26dBm
-3dBm
-16dBm
-16dBm
Figure 12 EXB Modules used with Starplex Multiplex
Multiplex Level Considerations
The levels recommended in this application note are 10 dB below microwave test tone levels.
Based upon the standard alignment for modems, the levels into and out of the modem are as
shown below:
Modem Test Tone Operating Level
Transmit Input. -16 dBm -26 dBm
Receive Output +7 dBm -3 dBm
It is highly recommended that you keep your modems set to the standard alignment and make any
required adjustments by changing the attenuator pads on the termination cards. This allows you
to standardize on your modem settings and use common modems for spares, without having to
re-set levels when changing modems.
Test Tone Level
The test tone level is the level used when the modems are aligned. Modems must not be
operated at test tone level for any purpose other than testing. Operating at test tone level will
cause distortion in the modems, cross-talk, and possibly microwave system over-deviation.
Operating Level
The operating level is set to 10 dB below test tone level to keep the signal out of distortion,
prevent cross-talk and prevent over-deviation. Do not run the system at less than 10 dB below
test tone level. Lower levels will result in degraded signal to noise ratio and will cause reduced
performance.