Geoscience Reference
In-Depth Information
As emergency communications systems evolved, they began to rely on “trunking” systems
followed by digital encoding to provide higher signal capacities on a limited number of chan-
nels. Similarly, the scanner technologies, selection, and programming to keep up with these
communication system changes also become more complex. The original scanners, like cell
phones, operated solely on analog signals. As scanner channels became overloaded by too
many people trying to communicate at the same time on a limited number of channels, scanner
systems developed “trunking” systems, where a computer would automatically select signal
channels for routing communications in ways that are similar to telephone trunk lines. The next
level of sophistication was introduced with digital coding and multiplexing, similar to the latest
digital cell-phone technology, allowing systems to run thousands of simultaneous communica-
tions over each individual channel.
Note:
With all of these potential complexities, don't count on taking your scanner out of its
box during an emergency and immediately tuning in to all the local dispatch communications.
Instead I suggest you practice a bit first, and learn the intricacies of your scanner and the local
communications networks, so when a true emergency does arise, you will already know exactly
how to access the information you are seeking.
A simple, relatively inexpensive analog scanner will work just fine in many locations, but
will be totally worthless in others. It all depends upon the local communication protocols and
technology used by the emergency communications systems within your area. You might as-
sume that most rural locations would use older analog technology and that the metropolitan
areas all have the latest high-tech digital technology, but you would be dead wrong. For ex-
ample, at the time I am writing this in 2011, they are still using analog technology for fire and
police communications in the greater Boston area, so your lower-cost scanners will work just
fine in and around Boston. However, in the remote Upper Peninsula area of Michigan, they are
using digital technology, so if you purchased a low-cost scanner for use in this area, it would be
worthless. How to know what technology is used in your area? Simply go to
www.policescanners.net
,
click on the link for “find a scanner for your area,” enter in your zip
code information, and this Web site will tell you what type of scanner technology is required
for your area. Of course, there are no guarantees that your local public services will not up-
grade their systems shortly after you purchase your new scanner!
If you are in an area where the scanners operate on digitally encoded signals, that usually
adds a higher level of complexity to getting your scanner programmed for operating efficiently
with the local emergency communications networks. And if you like to take your scanner on
