Lectrosonics UCR411 User Manual
UCR411
UHF RECEIVER
OPERATING INSTRUCTIONS
and trouble-shooting guide
LECTROSONICS, INC.
Rio Rancho, NM
www.lectrosonics.com
TABLE OF CONTENTS
DIGITAL HYBRID WIRELESS ............................................................................. 2
GENERAL TECHNICAL DESCRIPTION ............................................................ 3
FRONT PANEL CONTROLS AND FUNCTIONS ................................................ 6
REAR PANEL FEATURES ................................................................................... 7
MENU SELECTIONS FROM MAIN WINDOW.................................................... 8
FREQUENCY SCAN MODE.............................................................................. 10
ANTENNA USE AND PLACEMENT ................................................................. 11
INSTALLATION AND OPERATING INSTRUCTIONS ....................................... 12
UCR411 REPLACEMENT PARTS AND ACCESSORIES ................................ 12
TROUBLESHOOTING ....................................................................................... 13
SPECIFICATIONS AND FEATURES ................................................................ 14
SERVICE AND REPAIR ..................................................................................... 15
RETURNING UNITS FOR REPAIR................................................................... 15
WARRANTY ......................................................................................... Back cover
LOCKING AND UNLOCKING THE UCR411 .................................................. 6
DIGITAL HYBRID WIRELESS
(US Patent Pending)
The Lectrosonics Digital Hybrid WirelessTM uses innovative technology to combine
the new advantages of digital audio with the classic advantages of analog RF
transmission, thus delivering the superior sound quality of a digital system and the
excellent range of an analog system. A proprietary algorithm encodes the digital
audio information into an analog format which can be transmitted in a robust
manner over an analog FM wireless link. The receiver employs the latest filters, RF
amplifiers, mixers and detector to capture the encoded signal and a DSP recovers
the original digital audio.
This digital/analog hybrid technique has some very beneficial properties. Because
the information being transmitted is digitally encoded, immunity to noise is much
higher than a compandor can offer. Because the encoded audio is sent in analog
format, spectral and power efficiency and operating range are not compromised.
Under weak RF conditions, the received signal degrades gracefully, like an analog
system, delivering as much usable audio as possible at maximum range. Because
the audio is not companded, no compandor artifacts are present at any audio or RF
signal level. This greatly reduces the pumping and breathing problems commonly
found in wireless systems with compandors.
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UHF Wireless Digital HybridTM Receiver
GENERAL TECHNICAL DESCRIPTION
The UCR411 is a portable, high performance, tripleconversion, frequency synthesized, UHF receiver fully
compatible with all Lectrosonics 400 series transmitters.
The RF performance is extremely stable over a very
wide temperature range, making the UCR411 perfectly
suited to the rough environmental conditions found in the
field. The proprietary audio processing includes a digital
signal processor for very low distortion and a superior
signal to noise ratio.
The UCR411 features a menu-driven LCD graphic
display and a three button control panel as a convenient
means of viewing and altering user settings. The main
window, for example, 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 display
window. Other display windows show operating frequency, audio output level, battery status in tenths of
volts and test tone status. The frequency scan mode
provides a spectrum analyzer for a graphical means of
observing all signals “on the air” within the frequency
range of the receiver in order to find operating frequencies that are free of interference.
DIVERSITY RECEPTION
The UCR411 technology with SMART Diversity
minimizes dropouts in situations where multi-path
reflections can cause serious problems. The phase
diversity network and PIN diode RF switches are controlled by the microprocessor using a sophisticated
algorithm to use both antennas simultaneously. This
design keeps the receiver compact enough for camera
mounting or shoulder bag applications, yet provides
effective diversity reception.
TM
RF FREQUENCY TRACKING FRONT-END
AND MIXER
The receiver 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 UCR411 has a frequency
selective front-end section that tracks and tunes to the
desired signal frequency and rejects or “tunes out”
unwanted interfering signals. The design consists of four
varactor tuned ceramic transmission line resonators
controlled by the microprocessor to provide good selectivity. The low noise high current RF amplifier was
designed with feedback regulation for stability and
precise gain in order to handle stronger RF signals
without output overload. The first mixer is of new GaAs
technology that has a very high third order intercept
point. This produces a robust front-end that is as selec-
tive as fixed single frequency designs and is suitable for
use in close proximity to other receivers and transmitters
commonly used in field production “bag” systems.
MICROCONTROLLER, PLL AND VCO
CIRCUITS
The 8-bit microprocessor is truly the “heart” of the
UCR411 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 attenuator, and operate the front-end tuning, the PLL/VCO
circuits and the antenna phase switch. The UCR411
design and the advanced technology of the microprocessor control arguably set a new standard in wireless
microphone development.
IF AMPLIFIERS AND SAW FILTERS
The first IF low noise amplifier is controlled with feedback regulation and drives the first of two quartz SAW
(Surface Acoustical Wave) filters. The 244 MHz SAW
filters combine sharp tuning, constant group delay, wide
bandwidth and excellent temperature stability, far superior to conventional LC filters. The 244 MHz first IF
signal is converted to 10.7 MHz, filtered through two
ceramic filters for sharp selectivity, then converted to 300
kHz in one integrated circuit.
DIGITAL PULSE COUNTING DETECTOR
The UCR411 receiver uses an elegantly simple, yet
highly effective digital pulse detector to demodulate the
FM signal, rather than a conventional quadrature detector. This unusual design eliminates thermal drift, improves AM rejection, and provides very low audio
distortion.
DSP-BASED PILOT TONE
The 400 Series system design utilizes a DSP generated
ultrasonic pilot tone to control the receiver audio muting
(squelch). Brief delays at turn-on and turn-off eliminate
thumps, pops or other transients that can occur when the
power is switched on or off. The pilot tone frequency is
different for each of the 256 frequencies in the tuning
range of a system (frequency block.) This eliminates
squelch problems in multichannel systems where a pilot
tone signal can appear in the wrong receiver via intermodulation products. The DSP generated pilot tone also
eliminates the need for fragile crystals allowing the
receiver to survive shocks and mishandling much better
than older analog-based pilot tone systems.
Rio Rancho, NM – USA
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SMART SQUELCH
TM
The UCR411 employs a sophisticated squelching system
in an attempt to deliver the cleanest possible audio during
marginal conditions of reception. Any squelching system
faces inevitable trade-offs: squelch too much and valuable audio information may be lost, squelch too little and
excessive noise may be heard; respond too rapidly and
the audio sounds “choppy,” respond too sluggishly and
syllables or entire words can be cut off.
The UCR411 combines several techniques to achieve an
optimal balance, removing distracting noise, without the
squelching action itself becoming a distraction. One of
these techniques involves waiting for a word or syllable
to complete before squelching. Another incorporates
recent squelching history and recent signal strength,
adjusting squelching behavior dynamically for the most
serviceable result under variable conditions. Using these
and other techniques, the UCR411 can deliver acceptable audio quality from otherwise unusable signals.
In the PILOT TONE BYPASS mode, the squelch system
is disabled. Received audio remains unmuted at all
times with this setting.
SMART NOISE REDUCTION (SmartNRTM)
The UCR411 has been meticulously designed using the
best available low noise components and techniques.
Nonetheless, the wide dynamic range of digital hybrid
technology, combined with flat response to 20 kHz,
makes it possible to hear the -120 dBV noise floor in the
mic preamp, or the (usually) greater noise from the
microphone itself. (To put this in perspective, the noise
generated by the recommended 4k Ohm bias resistor of
many electret lavaliere mics is –119 dBV and the noise
level of the microphone’s electronics is much higher.) In
order to reduce this noise and thus increase the effective
dynamic range of the system, the UCR411 is equipped
with a Smart Noise Reduction algorithm, which removes
hiss without sacrificing high frequency response.
The Smart Noise Reduction algorithm works by attenuating only those portions of the audio signal that fit a
statistical profile for randomness or “electronic hiss”.
Because it isn’t simply a sophisticated variable low pass
filter as in Lectrosonics’s 195 and 200 series designs,
much greater transparency is thus obtained. Desired
high frequency signals having some coherence such as
speech sibilance and tones are not affected.
The Smart Noise Reduction algorithm has three modes,
selectable from a user setup screen. When switched
OFF, no noise reduction is performed and complete
transparency is preserved. All signals presented to the
transmitter’s analog front end, including any faint microphone hiss, will be faithfully reproduced at the receiver.
When switched to NORMAL, the factory default setting,
enough noise reduction is applied to remove most of the
hiss from the mic preamp and some of the hiss from
lavaliere microphones. The noise reduction benefit is
dramatic in this position, yet the degree of transparency
maintained is exceptional. When switched to FULL,
enough noise reduction is applied to remove most of the
hiss from nearly any signal source of reasonable quality,
assuming levels are set properly at the transmitter. This
additional noise reduction comes at the cost of some
transparency for low-level room noise, yet the algorithm
remains undetectable under most circumstances.
RF MODULE
ANTENNA
COMBINING
4
FILTER
uP uP
SYNTHESIZER
LCD
Display
Panel
Smart Diversity
UCR411 Block Diagram
PLL
uP
AMP
Filter
FILTER
LC
E PROM
CERAMIC
FILTER
2ND
MIXER
10.7 MHZ
MIXER
SAW
FILTER
244 MHz
IF AMP
SAW
FILTER
244 MHz
IF AMP
FILTER
HI-LEVEL
1st
VCO
2
FILTER
Attenuation
2nd
VCO
XTAL
CONTROLLED
3rd
OSCILLATOR
3RD MIXER
AND
IF AMP
COUNTING
DETECTOR
50KHz
LP FILTER
DIGITAL SIGNAL
PROCESSOR
PILOT TONE
DETECTOR
AUDIO
AMP
Output
Level
Adjust
Digital
Attenuator
XLR
OUT
50
2 (HI)
2K
1 (COMMON)
2K
3 (LO)
50
UHF Wireless Digital HybridTM Receiver
RF-CONTROLLED DIGITAL NOISE FILTER
In addition to SmartNR, the UCR411 contains an RF
sensitive variable frequency filter, which reduces high
frequency response under extremely weak RF conditions. This filter does nothing until the RF signal strength
drops below 3 uV at which point it begins to roll off high
frequencies. Usable audio remains unaffected, but
noise-ups or “hits” occurring near the fringe of reception
sound much less harsh.
OUTPUT LEVEL ADJUST
One of several setup screens is provided for adjusting
the audio output level in 1dB steps from -50 to +5dBu
using the UP and DOWN buttons on the front panel.
TEST TONE
The UCR411 provides a 1kHz audio test tone at the XLR
connector for level adjustment of connected equipment.
The level is adjustable from -50 to +5 dBu in 1 dB steps
to allow a precise match.
BATTERIES
The UCR411 operates on two 9V alkaline or lithium
batteries. Access to the battery compartment is gained
by lifting one end and turning the rear panel door. NOTE:
Do not use an alkaline and a lithium in the same unit.
Standard or “heavy duty” batteries are not recommended.
POWER SUPPLY
The UCR411 may be operated from an external DC
power source (see Specifications and Features section
for allowed voltages.) The receiver has a built-in PolyFuse to protect the unit. This fuse resets if the power
supply is disconnected for about 15 seconds. The power
section also has protection circuits that prevent damage
to the receiver if a positive ground power source is
applied.
LCD DISPLAY
The display has four main windows. Pressing the MENU
button rotates through each of these windows.
If the battery gets low on either transmitter or receiver, a
message will interrupt the display every few seconds and
flash a low battery warning.
After power is turned off and back on again, the unit
defaults to the main window and to the most recent
frequency, audio level, transmitter battery type and
locked/unlocked status settings. These settings are
retained even if the batteries are removed.
POWER UP SEQUENCE
The power-up sequence consists of four messages that
appear automatically over a period of a few seconds
after the power is switched on.
1) LOCKED or UNLOCKED status
2) The name LECTROSONICS
3) The model number and firmware revision numbers
4) The frequency block of operation
After these introductory messages are displayed, the
main window will appear.
The UCR411 is fully operational during the power up
sequence and will immediately respond to button pushes
made before the automatic sequence is completed. If a
valid transmitter signal is already present when the
receiver is turned on, the audio output will typically be
engaged somewhere in the middle of the power-up
sequence, following a brief delay to allow the audio
circuits to stabilize.
(See LOCKING AND UNLOCKING THE UCR411.)
POWER OFF
When the power switch is moved to the OFF position the
audio output is instantly muted (squelched) and the
message “POWERING OFF...” is displayed briefly before
switching off.
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