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m@ Multipath reception
Multipath reflections result from the nature of radio waves in
the FM band. They travel in straight lines and are reflected
from hills, large meta! structures and the like. When a signal
is received after bouncing off a building, it arrives at the an-
tenna later than the signal that came by a direct route. The
addition of the direct and reflected signals produces com-
plex variations
in amplitude
and
phase
throughout
the
broadcasting signal.
The result can be audible distortion
even though signal strength is high and tuning is correct.
If audible distortion occurs on a particular channel even
though the SIGNAL and TUNING meters indicate proper re-
ception conditions, the cause may be multipath reception.
To correct this condition
a directional
outdoor
antenna
should be installed following the suggestion given earlier in
this manual. To adjust the antenna, proceed as follows:
Adjustment using an oscilloscope
2. Tune in the affected station.
might be necessary
to use
a more
directional
antenna,
Adjustment using an amplifier
Broadcast
transmitting station
Fig. 7 Direct signal and reflected signal
KT-3300D
Rear panel
a
Oscilloscope
Fig. 8 Oscilloscope connection
(a) Undesirable
(b) Desirable waveform
Fig.9 Multipath waveform
KT-3300D (M)
9
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