Diagnostics; Multi-Channel System Checkout - Lectrosonics DSR4 Instruction Manual

DSR4

Diagnostics

Multi-channel System Checkout

Interference can result from a wide variety of sources
including TV station signals, other wireless equipment in
use nearby, or from intermodulation within a multi-chan-
nel wireless system itself. Regardless of how the fre-
quencies were coordinated, a final checkout procedure
is always a good idea.
Scanning with the RF spectrum analyzer built into the
DSR4 system will identify external RF signals, but it does
not address the compatibility of the selected frequen-
cies.
The pre-coordinated frequencies address in-system
intermodulation, but obviously cannot take into account
RF signals from external sources that may be present in
the location where the system will be operating.
1. Set up the system for testing.
Place antennas in the position in which they will be
used and connect to the receivers. Place trans-
mitters about 3 to 5 feet apart, about 25 to 30
feet from the receiver antennas. If possible, have
all other equipment on the set, stage or location
turned on as well, especially any mixing or record-
ing equipment that will be used with the wireless
system.
2. Set all receivers on clear channels.
Turn on all receivers, but leave the transmitters
off. Observe at the RF signal strength indicator
for each receiver module. If a signal is present,
change the frequency to a clear channel where
no signal is indicated. If a completely clear chan-
nel cannot be found, select the frequency with the
lowest RF level indication. Once all receiver mod-
ules are on clear channels, go to step 3.
3. Turn each transmitter on one at a time.
Start with all transmitters turned off. As you turn
on each one, look at the matching receiver to
verify a strong RF signal is received. Then, look at
the other receivers and see if one of them is also
picking up the signal. Only the matching receiver
should indicate a signal. Change frequencies on
either system slightly until all channels pass this
test, then check again to see that all channels are
still clear as done in step 2.
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4. Turn each transmitter off one at a time.
With all transmitters and receivers turned on, turn
each transmitter off one at a time, in turn, and look
at the RF level indicator on the matching receiver
module. The RF level should disappear or drop to
a very low level. If it does not, change frequency on
that receiver and transmitter and try it again. When
a clear frequency is found, turn the transmitter on
and move on to the next channel.
IMPORTANT: Any time a frequency is changed
on any of the systems in use, you must start at
the beginning and go through this procedure
again for all systems. With a little practice, you
will be able to do this quickly and save yourself
some "multi-channel grief."
LECTROSONICS, INC.