Lectrosonics VRFIELD (Narrowband) - Manual (Page 24)

VR Field
The following guidelines should be observed when
selecting compatible frequencies:
1.. Set.1.and.Set.2.are.NOT.compatible.
Proper coordination requires that all frequencies be
taken from either Set 1 or Set 2, but not a combina­
tion of the two.
(The remaining guidelines make the assumption
that you are choosing frequencies within one
frequency set.)
2.. Frequencies.within.an.individual.frequency.
block.in.the.same.Set.are.compatible..
(Example: All 16 frequencies in
Block 25, Group A and B)
3.. Frequencies.from.adjacent.blocks,.but.different.
Groups.are.compatible.
(Example: Block 21, Group C frequencies
are compatible with
Block 22, Group D frequencies)
4.. Frequencies.from.adjacent.blocks.and.the.same.
Group.are.NOT.compatible.
(Example: Block 26, Group B frequencies
are NOT compatible with
Block 26, Group B frequencies)
It is highly recommeneded that you choose frequencies
that are in the same set and same group.
By following these guidelines, it is possible to locate a
number of operating frequencies early in the production
that are free from intermodulation, then refine the list
during system setup.
Using the Scan Function
Refer to the section titled “Using Scan to Find Clear
Channels” for details on how to use the built-in spec­
trum scanner.
Interference can result from a wide variety of sources
including TV station signals, other wireless equipment
in use nearby, or from intermodulation within the VR
Field System itself. The RF spectrum analyzer built into
the VR Field System uses a receiver in each frequency
block to scan the tunable spectrum and find clear chan­
nels with little or no interference. After scanning and
finding the needed number of clear channels, one final
procedure is necessary to verify the compatibility of the
chosen frequencies.
Turn on all transmitters and receivers and verify there
is a strong RF signal for each receiver. Turn each
transmitter off one at a time and observe the RF level
indicator on the matching receiver. 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.
Any time a frequency is changed on any of the systems
in use, you must start at the beginning and go through
this procedure for all systems. This will test for higher
order intermodulation from all signal sources and avoid
interference.
Checking Compatibility of New Frequencies
Found with the Scan Function
First, make sure that the frequencies you have selected
are at least 400 kHz apart. This is four steps of the right
hand switch if you are using the two character settings,
or 0.400 MHz on the frequency display.
The following steps must be conducted in the site
where the unit will be used. Also try to have all other
equipment that will be used turned on.
1. Leave transmitters OFF. Turn on the VR Field and
check that all receivers are shown on the Overview
Screen. Set up antennas the way they will be used
in the actual production.
2. Look for RF activity on any of the receivers and
change frequencies on those that indicate some
activity. If completely clear frequencies cannot be
found, set each receiver to a frequency with the
least RF activity.
3. Set the transmitter frequencies to match the receiv­
ers in the VR Field.
4. Turn each transmitter ON one at a time and check
to see that a strong RF signal is indicated at the
matching receiver, and that audio is produced
through each transmitter/receiver system. Make fine
adjustments as needed so that each system oper­
ates by itself.
5. Turn all transmitters ON, then turn them OFF one at
a time and look to see if the RF signal disappears
on the matching receiver.
6. If an RF signal is still indicated on the receiver when
its transmitter is turned off, turn the other transmit­
ters OFF one at a time to see if one of them is gen­
erating the RF signal indicated. It is also possible
that two other transmitters can combine to generate
an interfering RF signal on another frequency.
7. Make fine adjustments to the frequencies on either
the offending or affected system as needed so the
system will pass the tests in steps 4 and 5.
Call Lectrosonics
Lectrosonics uses a proprietary computer program to
perform thousands of calculations and identify vari­
ous interfering signals. Potential problems and trouble
areas can be identified in advance, and proposed new
frequencies or other solutions can be suggested. This
service is offered to authorized Lectrosonics dealers
and other customers who are using Lectrosonics ® wire­
less microphone and wireless IFB systems.
LECTROSONICS, INC.