Lectrosonics UMC16a - Manual (Page 5)

ANTENNA USE AND PLACEMENT
Position the antennas so that they are not within 3 or 4 feet of large metal surfaces. If this is not possible, try to
position the antennas so that they are as far away from the metal surface as is practical. It is also good to
position the receiver so that there is a direct “line of sight” between the transmitter and the receiver antenna. In
situations where the operating range is less than about 50 feet, the antenna positioning is much less critical.
A wireless transmitter sends a radio signal out in all directions. This signal will often bounce off nearby walls,
ceilings, etc. and a strong reflection can arrive at the receiver antenna along with the direct signal. If the direct and
reflected signals are out of phase with each other a cancellation may occur. The result would be a “drop-out.” A
drop-out sounds like either audible noise (hiss), or in severe cases, may result in a complete loss of the carrier
and the sound when the transmitter is positioned in certain locations in the room. A drop-out normally sounds like
“hum” or “hiss.” Moving the transmitter even a few inches will change the sound of the hum or hiss, or eliminate it.
A drop-out situation may be either better or worse as the crowd fills and/or leaves the room, or when the transmit­
ter or receiver is operated in a different location.
Lectrosonics receivers offer a sophisticated design which overcomes drop-out problems in almost any imaginable
situation. In the event, however, that you do encounter a dropout problem, first try moving the antenna at least 3
or 4 feet from where it was. This may alleviate the drop-out problem on that antenna. If drop-outs are still a
problem, try moving the antenna to an entirely different location in the room or moving the antennas in closer to
the transmitter location. By observing the LEDs on the front panel, you can determine which antenna is suffering
weak signals.
Lectrosonics transmitters radiate power very efficiently, and the receivers are very sensitive. This reduces drop­
outs to an insignificant level. If, however, you do encounter drop-outs frequently, call the factory or consult your
dealer. There is probably a simple solution.
REFLECTIVE SURFACE
DIRECT SIGNAL
INDIRECT SIGNAL
DIRECT SIGNAL
INDIRECT SIGNAL
TRANSMITTER
PHASE
CANCELLATION
Multi-Coupler
Figure 4 - Multi-path dropout
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