Codan Radio MT-4E Paging - Manual (Page 14)

USER GUIDE | MT-4E PAGING SYSTEMS
Chapter 1: Introduction to Paging Page 6
SIMULCAST
Simulcast is a signaling technique that broadcasts the same signal over multiple sites in a network with
precise control over frequency, phase (timing), and amplitude to avoid signal cancellation in the overlap
areas. The simultaneous broadcast of a signal (analog audio, digital audio or data) by a number of
transmitters on a single radio frequency from multiple transmitters can have overlapping areas. Figure
1-2 shows a simulcast system with three transmitters (Site A, B and C) on the same RF frequency.
Figure 1-2: Simulcast System
In Non-Overlap areas, Pager A receives the signal from only one transmitter, which is the preferable
condition. Pager B receives a signal from both Site B and Site C. This area is known as an Overlap (or
non-capture) area and is the critical area in a simulcast system.
Why use Simulcast?
Simulcast paging systems penetrate into buildings and offers seamless wide area coverage better than
other methods of transmission which only use one site at a time.
Simulcast can require a more complex system design, additional RF engineering, and increased
maintenance. In addition, simulcast requires more costly hardware than a conventional paging system
and some systems also run the risk of having the signal blanked out in small areas by destructive
interference such as multipath (a typical RF problem).
Overlap
Pager A
SITE A SITE B
SITE C
Overlap
Overlap
Non-Overlap Non-Overlap
Non-Overlap
Pager B
Overlap