Realistic PRO-43 - Page 23

hear an emergency call. Never go to the scene of an emer¬
gency. It is the most dangerous thing you could do.
Find out if there is a local club that monitors your
community’s frequencies. Perhaps a local electronics repair
shop that works on equipment similar to your scanner can
give you channel frequencies used by local radio services. A
volunteer police or fire employee can also be a good source
for this information.
As a general rule on VHF, most activity is concentrated be¬
tween 153.785 and 155.98 MHz and then again from 158.73
to 159.46 MHz. Here you find local government, police, fire,
and most emergency services. If you are near a railroad or
major railroad tracks, look around 160.0 to 161.9 for signals.
You can hear commercial aircraft transmissions between
118 and 136.975 MHz. Military aircraft operate between 225
and 400 MHz.
In some large cities, the UHF bands are used for emergency
services. Here, most of the activity is between 453.025 and
453.95 MHz and between 456.025 and 467.925 MHz.
In the UHF band, frequencies between 456.025 and 459.95
MHz and between 465.025 and 469.975 MHz are used by
mobile units and control stations associated with base and
repeater units that operate 5 MHz lower (that is, between
451.025 and 454.95 MHz and between 460.025 and
464.975 MHz). This means if you find an active frequency
inside one of these spreads, you can look 5 MHz lower (or
higher) to find the base station/repeater for that service.
A newer technology is now available that uses the 800 MHz
band for many services. Trunked radio, introduced to busi¬
ness systems in 1975, is now used by public safety agen¬
cies. With up to twenty channels available, the transmitter
automatically selects an unused frequency each time it is
activated. Several agencies can share such a system with¬
out interfering with each other. This system can provide se¬
cure communications for selected units, with unselected
units unable to hear the message.
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