Albrecht AE 69-2H Bedienungsanleitung Seite 38

repeater systems). Any time one of them transmits, their
transmission always goes out on the same frequency. Up
until the late 1980's this was the primary way that radio
systems operated.
Even today, there are many 2-way radio users who operate
using a conventional system:
Aircraft (not to be received with this scanner
•
model)
• Amateur radio
PMR users
•
Broadcast AM/FM/TV stations (not to be received
•
with this scanner model)
• Many other business radio users
When you want to store a conventional system, all you need
to know is the frequencies they operate on. When you are
scanning a conventional system, the scanner stops very
briefly on each channel to see if there is activity. If there isn't,
the scanner quickly moves to the next channel. If there is,
then the scanner pauses on the transmission until it is over.
Simplex Operation
Simplex systems use a single frequency for both transmit
and receive. Most radios using this type of operation are
limited to line-of-sight operation. This type of radio is
frequently
inexpensive consumer radios such as PMR radios. The range
is typically 1.5-12 km, depending upon the terrain and many
other factors.
Repeater Operation
Repeater systems use two frequencies: one transmits from
the radio to a central repeater; the other transmits from the
repeater to other radios in the system. With a repeater-based
system, the repeater is located on top of a tall building or on a
radio tower that provides great visibility to the area of
operation. When a user transmits (on an input frequency), the
signal is picked up by the repeater and retransmitted (on an
output frequency). The user's radios always listen for activity
on the output frequency and transmit on the input frequency.
Since the repeater is located very high, there is a very large
line of sight. Typical repeater systems provide coverage out to
about a 40 km radius from the repeater location.
Where to obtain more information
By itself, this manual really only provides part of what you
need to know to have fun scanning-how to program and use
the scanner.
38
used at construction job sites,
English
and with