Fixed Receivers - ASCOM T942C System Installation

System Installation
Ascom Paging System
3

Fixed Receivers

Fixed Receivers are connected to a Receiver Interface (RI), which in turn is connected to the
A-bus. Up to four receivers may be connected to the same RI, each with a separate
twisted-pair that must not exceed 1 km. Move the RI closer to the receivers if the distance
exceeds 1 km or use modems to extend the A-, B-bus of the RI.
Note that the twisted-pair (R-line) between each receiver and its interface is not included
in the system modular bus and must therefore be connected separately, even when the
units are mounted together. When the Receiver is not activated, this line always carries a
quality tone of about 2.0 ± 0.2 Vp-p measured between L1 and L2.
When the Receiver is activated, the data signal, a sinusoidal signal of about 
5.0 ± 0.2 Vp-p, is superimposed on the quality tone. The quality tone can be generated at
four different frequencies corresponding to four quality levels.
The line is not polarized
.
Figure 4. Receivers connected to the Central Unit via the Receiver Interface.
10 October 2013 / Ver. D
Central Units
Receiver
Interface
A-bus
Fixed
Fixed
Receiver
Receiver
1 km
1 km
TD 90227GB
6