Lectrosonics UDR700, Instruction Manual

UDR700 / UM700 / UT700 

supplied with 48 Volts.  A unique 16-position sensitivity 
control at the element itself can also adjust the sensitiv­
ity over a 15 dB range.  This is in addition to the normal 
gain control in the wireless microphone.  The result is 
the widest dynamic range of any condenser mic in a 
wireless microphone. 

The VariMic

TM

 has a three-point damped rubber suspen­

sion to reduce high frequency handling noise and a 
generous sized windscreen to keep wind noise and 
breath pops away from the microphone. 

Comparing Diversity Reception and Rota-Versity

™ 

The UDR700’s new approach to diversity reception is a 
vast improvement over traditional designs.  Traditional 
analog diversity reception designs employed techniques 
ranging from simple antenna and audio signal switching 
using one or two receivers, to dual-receiver ratio 
combining systems.  In the digital realm, even more 
advanced techniques are possible to analyze and 
correct antenna phase. 

A popular phrase, “true diversity,” arose in defense of 
dual-receiver audio switching diversity designs versus 
very low cost receivers that simply had two antennas 
mounted on a single unit.  Diversity reception can be 
implemented by mixing or selecting the audio from two 
separate receivers, or by various antenna combining 
techniques ahead of the receiver.  In reality, all receiver 
designs can aptly be called “true diversity” if they make 
use of two or more antennas that are receiving diverse 
(uncorrelated) signals. 

Two diversity designs found in use today include Audio 
Switching Diversity and Ratio Diversity.  Both offer some 
improvement in 
audio reception, 
but with a 
significant 
increase in 
equipment costs 
because of the 
need for two 
receivers. 
SmartDiversity

™ 

from 
Lectrosonics is 
different. 

SmartDiversity

™ 

SmartDiversity

™

 is a microprocessor controlled tech­

nique that automatically analyzes audio content and RF 
levels to determine optimum timing for the switching 
activity.  Active analog antenna phase switching tech­
niques use both antennas at the same time, with 180 
degree phase switching to help keep the received 
signals in phase and minimize dropouts.  When the 
overall RF signal strength quickly drops, the phase of 
one antenna is switched 180 degrees.  If the switch 
increases the RF 
level, it will remain 
latched in that 
position until the 
RF level quickly 
drops again.  Both 
antennas are used 
at the same time, 
so overall operating 
range is also 
improved. 

Rota-Versity

™ 

ANTENNA PHASE

SWITCHING 

RECEIVER 

180 DEGREE PHASE 

SWITCHING 

MICROPROCESSOR 

RECEIVER A 

RECEIVER A 

SWITCH 

RECEIVER AUDIO OUTPUT

SELECTED BY RF LEVEL 

AUDIO SWITCHING

DIVERSITY 

AUDIO 
OUTPUT 

RATIO DIVERSITY 

AUDIO COMBINING 

AUDIO 
OUTPUT 

Rota-Versity

™

 is only possible in the digital realm. Rota-

Versity

TM

 uses a four-way phase shifter to combine the 

output of two antennas in any of four phase angles, 
each 90 degrees apart, regardless of RF levels.  Hun­
dreds of times per second, all of the phase angles are 
explored, with the angle offering the best reception 
used for the audio data.  The result is the diversity 
system “tracks” the phase shift between the two anten­
nas to ensure that they always add to one another (they 
are always less than 90 degrees out of phase).  Multi-
path dropouts are minimized and operating range is 
maximized by using both antennas simultaneously. 
Because it times 
phase switches 
to happen only 
during digital 
packet headers 
where no audio 
is being con­
veyed, Rota­
versity

™

 is also 

transparent and 
cost effective . 

ROTA-VERSITY™ DIGITAL 

PHASE CORRELATION 

0 

270 

90 

MICROPROCESSOR 

RECEIVER

180 

PHASE CORRECTED

COMBINING 

LECTROSONICS, INC. 

RECEIVER A 

RECEIVER A 

RECEIVER AUDIO OUTPUTS 

MIXED IN OptiBlend™ RATIO 
CONTROLLED BY RF LEVEL 

AUDIO 

PANNING 

CIRCUIT 

8