Lectrosonics UCR401 - Manual (Page 7)

UHF Digital Hybrid Wireless ® Receiver
Rio Rancho, NM 7
The UCR401 is a portable, high performance, triple-
conversion, frequency synthesized, UHF receiver fully
compatible with all Lectrosonics 400 Series transmit-
ters, Lectrosonics wideband UHF analog systems. DSP
compatibility modes also provide compatibility with
some other transmitter brands. The RF performance is
extremely stable over a very wide temperature range,
making the UCR401 perfectly suited to the rough
environmental conditions found in field production. The
combination of digital audio with analog RF produces
superb audio quality and extended operating range.
The UCR401 front panel features a menu-driven LCD
interface and three control buttons to conveniently view
and alter user settings. The main LCD window simulta-
neously displays the pilot tone indicator, phase diversity
activity, RF level, audio level, battery status for both
transmitter and receiver. It is also possible to bypass
the pilot tone squelch from the main display window for
diagnostic purposes. Other windows display operating
frequency, audio output level, battery voltage and test
tone status.
A built-in spectrum analyzer scans across the tuning
range of the receiver to locate RF signals in the vicinity
and find clear operating frequencies.
Diversity Reception
Microprocessor controlled antenna phase combining
keeps the receiver small, with low power consumption,
yet it is still able to deal effectively with multi-path drop-
outs. SmartDiversity™ analyzes both the incoming RF
level and the rate of change in RF level to determine the
optimum timing for phase switching, and the optimum
antenna phase. This adaptive technique operates over
a wide range of RF levels to anticipate dropouts before
they occur. The system also employs “opportunistic
switching” to analyze and then latch the phase in the
best position during brief squelch activity.
RF Front-End and Mixer
The UCR401 is frequency agile and can be set to
operate on any one of 256 frequencies within its tuning
range. To significantly reduce unwanted interference
and intermodulation problems, the UCR401’s front-end
is tuned to the desired frequency band and rejects or
“tunes out” unwanted out-of-band signals. Two tuned
HI-Q ceramic transmission line resonators prior to a low
noise, high current RF amplifier provide good selectiv-
ity. A LC bandpass filter after the RF amplifier provides
added insurance against strong RF interference, and
the first mixer has a very high third order intercept point.
The overall design ensures stability, selectivity and pre-
cise gain in order to handle strong RF signals without
input overload.
Microcontroller, PLL and VCO Circuits
The 8-bit microprocessor is truly the “heart” of the
UCR401 receiver. It monitors user command inputs
from the front panel control buttons and numerous other
internal signals such as RF level, audio levels, pilot tone
levels and external/internal power voltages. Outputs
from the microcontroller drive the LCD display and
backlight, control the squelch and audio output attenu-
ator, and operate the front-end tuning, the PLL/VCO
circuits and the antenna phase switch. The UCR401
design and the advanced technology of the micropro-
cessor control arguably set a new standard in wireless
microphone development.
General Technical Description
2 (HI)
1 (COMMON)
3 (LO)
50
50
5K
5K
uP
LCD
Display
Panel
PILOT TONE
DETECT
FILTER
DIGITAL SIGNAL
PROCESSOR
Attenuation
CERAMIC
FILTER
2ND
MIXER
10.7 MHZ
SAW
FILTER
244 MHz
IF AMP
A-D
CONVERTER
D-A
CONVERTER
AMP
2nd
VCO
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
UCR401
BLOCK DIAGRAM
ANTENNA
COMBINING
FILTER
E PROM 2
1st
VCO
Smart Diversity
FILTER
PLL
SYNTHESIZER
LC
Filter
Output
Level
Adjust
Digital
Attenuator