4
UCR301
Professional Audio Products Since 1971
INTRODUCTION
The UCR301 is a portable, high performance, triple-
conversion, frequency synthesized, UHF receiver fully
compatible with all Lectrosonics 300 series transmitters.
The RF performance is extremely stable over a very
wide temperature range, making the UCR301 perfectly
suited to the rough environmental conditions found in the
field. The proprietary audio processing includes a dual-
band compandor for very low distortion and a superior
signal to noise ratio. The Smart Squelch™ system is
operated by a separate pilot tone and mutes the audio
output directly at the output connector.
The UCR301 features a menu-driven LCD and a three
button control panel (MENU, SELECT Up and SELECT
down). The combination of icons and text in the display
provides convenient and efficient access to system
functions and status using the menu button. For
example, the Main Window alone shows the pilot tone
indicator, antenna diversity phase, RF level, audio level,
receiver battery status and transmitter battery status. It
is also possible to bypass the pilot tone from the Main
Window. Other windows show operating frequency,
audio output level, battery status in tenths of volts, test
tone, and provide for selection of levels or functions
using the SELECT buttons. The frequency scan mode
provides a graphic means to observe all signals “on the
air” within the unit’s frequency range in order to find
useable operating frequencies free of interference.
SMART DIVERSITY™
The Smart Diversity™ antenna phase switching
technique keeps the receiver compact enough for
camera mounted or shoulder bag applications. Smart
Attenuation
IF
FILTER
2 (HI)
1 (COMMON)
3 (LO)
50
50
2K
2K
u P
L C D
D i s p l a y
P a n e l
PILOT TONE
DETECTOR
FILTER
AMP
2nd
VCO
2:1
EXPANDER
TREBLE
2:1
EXPANDER
BASS
23 KHZ
LP
FILTER
XLR
OUT
HI-LEVEL
MIXER
RF MODULE
3RD MIXER
AND
IF AMP
50KHz
LP FILTER
XTAL
CONTROLLED
3rd
OSCILLATOR
SAW
FILTER
244 MHz
IF AMP
COUNTING
DETECTOR
AUDIO
AMP
UCR201
BLOCK DIAGRAM
VARIABLE
CUT-OFF
LP FILTER
ANTENNA
SWITCHING
FILTER
E PROM
2
1st
VCO
Smart Diversity
Smart Squelch
2ND
MIXER
10.7 MHZ
FILTER
SYNTHESIZER
LC
Filter
Digital
Squelch
Output
Level
Adjust
Squelch
Digital
Attenuator
GENERAL TECHNICAL DESCRIPTION
Diversity™ effectively minimizes dropouts in situations
where multi-path reflections can cause serious
problems.
RF MODULE
The UCR301 RF Module retains the stability of fixed
frequency designs with the added flexibility of a
frequency agile designs. This is done with a robust
wideband RF section (30 MHz at -3 dB) with good third
order intermodulation performance.
The problem of frequency agility is further compounded
because “on the fly” frequency changes cannot be made
on any type of wireless system. For example, if there is
suddenly an interference problem with a system in use
(on stage for instance) a frequency change cannot be
made without interrupting the program. In multichannel
applications, changing the frequency of one system will
usually produce all kinds of new intermodulation
problems with the other systems operating in the same
location. The UCR301 offers a new approach to
frequency agile receiver design.
DOUBLE BALANCED DIODE MIXERS
In all wireless receivers, a mixer is used to convert the
carrier frequency to an intermediate frequency, or IF,
where most of the filtering and signal amplification (gain)
takes place. The UCR301 uses a low noise GaAs mixer
having a robust 3
rd
order of +25 dBm to overcome
intermodulation problems common with less
sophisticated designs. The unusually high IF frequency
output from the first mixer (244 MHz) offers increased
image rejection and is followed by low noise amplifiers,
SAW filters and two more levels of IF mixing to preserve
the superior RF performance
UCR301
Block Diagram
