Lectrosonics VR Field (Wideband) - Manual (Page 13)

Digital Hybrid Wireless™ Modular Receiver System
Rio Rancho, NM, USA 13
Select the receiver module with Receiver Select Button
and rotate the MENU/SELECT control to the desired
mode. Listen to the audio signal as you rotate the knob
and select the mode that best fits the situation.
Note: If the selected Receiver Module is part of
a ratio or frequency diversity pair, the mode will
automatically be set for both receiver modules in
the pair.
When any Compat Mode other than Dig. Hybrid is se-
lected, FIXED will automatically be selected.
In this example, receiver modules 4, 5 and 6 are set to
the FIXED mode with no adjustment available.
Selecting Diversity Modes
Navigate to the DivMode setup screen.
Three diversity reception modes are available:
• Switched Diversity uses one receiver module per
audio channel.
• Ratio Diversity (OptiBlend TM ) uses two receiver
modules per audio channel.
• Frequency Diversity uses two receiver modules
and two transmitters per audio channel.
Press the Receiver Select Buttons to enter the setup
screens for the receiver modules.
Switched Diversity
In this mode the signals from both antennas are com-
bined into a single receiver module, with the phase of
one of them inverted back and forth so that they always
add to one another. The process reduces dropouts and
provides a stronger signal than a single antenna.
Ratio Diversity (OptiBlend
TM
)
Ratio diversity uses two adjacent receiver modules to
pick up a single transmitter. The audio outputs of the
modules are blended (mixed) together, using more or
less audio from each module based upon which module
has the stronger RF signal.
Ratio diversity anticipates dropouts before they occur,
rather than waiting until the RF signal level is very weak
and on the verge of noise or dropout. The comparison
of the RF signal levels in the modules begins when the
RF level is still high, so the circuit can blend in more
audio from the module with the stronger signal before
the signal decays enough to cause noise.
The blending action is smooth and seamless to avoid
any audible artifacts that can occur with abrupt switch-
ing. Most of the time both receiver modules have good
signals, so the audio is blended equally, which improves
the signal to noise ratio by 3 dB.
The blended audio appears at the rear panel XLR out-
puts of both modules.
Frequency Diversity
Frequency Diversity differs from the other two diversity
modes in that it uses two receiver modules and two
transmitters operating on different frequencies. The pur-
pose of this mode is to have redundancy in the system
for critical productions, such as live television, to guard
against failures caused by dead batteries and multipath
dropouts. The blending process to combine the audio
from the receiver modules is the same as that used for
OptiBlend ratio diversity.
Frequency Diversity requires that the levels of the two
audio channels to be closely matched to avoid au-
dible level changes as the blending action takes place.
In order for this blending to work properly, a special
test mode helps to get the transmitter levels exactly
matched. The test mode is automatically activated when
the DivMode Setup Screen is active and Frequency
Diversity is selected, as shown in the LCD photo above.