Lectrosonics UCR401-21 User manual

UCR401

Compact Wireless Receiver

INSTRUCTION MANUAL

Featuring

Digital Hybrid Wireless® Technology

U.S. Patent 7,225,135

Fill in for your records:

Serial Number:

Purchase Date:

Rio Rancho, NM, USA
www.lectrosonics.com

UCR401

2

LECTROSONICS, INC.

UHF Digital Hybrid Wireless® Receiver

Digital Hybrid Wireless

TM

The Lectrosonics Digital Hybrid WirelessTM uses in­novative technology to combine the new advantages of
digital audio with the 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 state-of-the-art 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 being­transmitted 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.
Since the audio is free of compandor artifacts, pumping
and breathing problems are also greatly reduced.

Rio Rancho, NM

3

UCR401

4

LECTROSONICS, INC.

UHF Digital Hybrid Wireless® Receiver

Table of Contents

General Technical Description ..............................................................................................................................................................7

Diversity Reception ...............................................................................................................................................................................7

MIicrocontroller, PLL and VCO Circuits.................................................................................................................................................7

IF Amplifiers and SAW Filters ...............................................................................................................................................................8

Digital Pulse Counting Detector ............................................................................................................................................................8

DSP-Based Pilot Tone ...........................................................................................................................................................................8

Smart Squelch

Smart Noise Reduction (SmartNR™) ....................................................................................................................................................8

Supersonic Noise-Based Dynamic Filter and Squelch .........................................................................................................................9

RF-Controlled Digital Noise Filter .........................................................................................................................................................9

Audio Output Level ............................................................................................................................................................................... 9

Test Tone ...............................................................................................................................................................................................9

Batteries ................................................................................................................................................................................................ 9

Power Supply ........................................................................................................................................................................................ 9

LCD Display ..........................................................................................................................................................................................9

Power Up Sequence .............................................................................................................................................................................9

Power Off ..............................................................................................................................................................................................9

Front Panel Controls and Functions ...................................................................................................................................................10

LCD Screen ........................................................................................................................................................................................10

MENU Button ......................................................................................................................................................................................10

SELECT Up/Down Buttons .................................................................................................................................................................10

Power ON/OFF Switch ........................................................................................................................................................................ 10

Rear Panel Features .............................................................................................................................................................................10

XLR Audio Output Jack .......................................................................................................................................................................10

Power Input Jack .................................................................................................................................................................................10

Main Window (LCD) .............................................................................................................................................................................. 11

Menu Selections from Main Window ...................................................................................................................................................12

Frequency Window..............................................................................................................................................................................12

Battery Level Window .........................................................................................................................................................................12

Setup Window .....................................................................................................................................................................................13

LEVEL .................................................................................................................................................................................................13

TONE ..................................................................................................................................................................................................13

TXBAT .................................................................................................................................................................................................13

PHASE ................................................................................................................................................................................................13

SmtNR ................................................................................................................................................................................................13

TUNING ..............................................................................................................................................................................................14

COMPAT .............................................................................................................................................................................................14

Frequency Scan Mode .........................................................................................................................................................................15

Scan & View Window Elements ..........................................................................................................................................................15

Fine View Window Elements ............................................................................................................................................................... 15

Antenna Use and Placement ...............................................................................................................................................................16

Setup and Operating Instructions .......................................................................................................................................................17

Installing/Replacing Batteries..............................................................................................................................................................17

Adjusting Audio Output .......................................................................................................................................................................17

Finding Clear Frequencies ..................................................................................................................................................................18

Locking and Unlocking the UCR401 ...................................................................................................................................................19

Pre-coordinated Frequencies ..............................................................................................................................................................20

Compatible Frequency Table ...............................................................................................................................................................20

Compatibility Diagram .........................................................................................................................................................................21

Diagnostics ...........................................................................................................................................................................................22

Multi-channel System Checkout..........................................................................................................................................................22

Pilot Tone Bypass ................................................................................................................................................................................22

Replacement Parts and Accessories ..................................................................................................................................................23

Troubleshooting ....................................................................................................................................................................................24

Specifications and Features ................................................................................................................................................................26

Service and Repair ...............................................................................................................................................................................27

Returning Units for Repair ..................................................................................................................................................................27

™

.......................................................................................................................................................................................8

Rio Rancho, NM

5

UCR401

6

LECTROSONICS, INC.

General Technical Description

UHF Digital Hybrid Wireless® Receiver

RF MODULE

ANTENNA

COMBINING

LCD

Display

Panel

Smart Diversity

FILTER

PLL

SYNTHESIZER

AMP

FILTER

uP

2

E PROM

LC

Filter

1st

VCO

SAW

FILTER

244 MHz

IF AMP

2nd

VCO

FILTER

The UCR401 is a portable, high performance, triple­conversion, frequency synthesized, UHF receiver fully
compatible with all Lectrosonics 400 Series transmit­ters, 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 simulta­neously 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 drop­outs. 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.

HI-LEVEL

MIXER

SAW

FILTER

244 MHz

IF AMP

PILOT TONE

DETECT

Attenuation

CERAMIC

FILTER

2ND

MIXER

10.7 MHZ

XTAL

CONTROLLED

3rd

OSCILLATOR

3RD MIXER

AND

IF AMP

COUNTING

DETECTOR

50KHz

LP FILTER

A-D

CONVERTER

DIGITAL SIGNAL

PROCESSOR

D-A

CONVERTER

UCR401

BLOCK DIAGRAM

Output

Level

Adjust

AUDIO

AMP

Digital

Attenuator

XLR

OUT

50

5K

1 (COMMON)

5K

50

2 (HI)

3 (LO)

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 selectiv­ity. 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 pre­cise gain in order to handle strong RF signals without
input overload.

MIicrocontroller, 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 attenu­ator, and operate the front-end tuning, the PLL/VCO
circuits and the antenna phase switch. The UCR401
design and the advanced technology of the micropro­cessor control arguably set a new standard in wireless
microphone development.

Rio Rancho, NM

7

UCR401

IF Amplifiers and SAW Filters

The first IF stage at 244 MHz employs two state-of-the­art SAW (surface acoustic wave) filters. The use of two
filters significantly increases the depth of filtering while
preserving sharp skirts, constant group delay, and wide
bandwidth. Though expensive, this special type of filter
allows primary filtering as early as possible, at as high a
frequency as possible before high gain is applied to the
signal for maximum image rejection.

Since these filters are made of quartz, they are very
temperature stable. After the SAW filter, the 244 MHz IF
signal is converted to 10.7 MHz IF and then to the low
frequency of 300 kHz. Only then is the majority of the
gain applied, just before the signal is converted to audio
with a pulse counting detector. Although 300 kHz is very
unconventional for an IF in a wide deviation (±75 kHz)
system, it offers outstanding AM rejection figure over
a very wide range of signal strengths and produces an
excellent noise improvement at low signal strengths.

Digital Pulse Counting Detector

The UCR401 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 Digital Hybrid system design uses a DSP gener­ated ultrasonic pilot tone to control the receiver audio
muting (squelch). Brief delays are applied to eliminate
thumps, pops or other transients that can occur when
the power is turned 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 fragile crystals, allowing the receiver to
survive shocks and mishandling much better than older
analog-based pilot tone systems.

Note: This description applies only in 400 Series
mode. In 200 Series mode, only one pilot tone
frequency is used on all channels, emulating
the original crystal-based system. In other
compatibility modes, no pilot tone is used.

Smart Squelch

Any squelching system faces inevitable trade-offs:
squelch too aggressively and valuable audio information
may be lost. Squelch too little and excessive noise may
be heard. Respond too rapidly and the audio will sound
“choppy.” Respond too sluggishly and syllables or entire
words can be cut off.

The UCR401 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 technique

™

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 UCR401 can
deliver acceptable audio quality from otherwise unus­able signals.

Smart Noise Reduction (SmartNR™)

Note: The SmartNR setting is user selectable
only in 400 Series mode. In other modes, noise
reduction is applied in such a way as to emulate
the original analog system as accurately as
possible and is not user adjustable.

The UCR401 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 4 k 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 the UCR401 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 analog de­signs, much greater transparency is obtained. Desired
high frequency signals having some coherence are not
affected, such as speech sibilance and tones.

The Smart Noise Reduction algorithm has three modes,
selectable from a user setup screen: OFF, NORMAL,
and FULL. 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,
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
significant 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, and some high frequency environmental noise. The
optimal setting for each application is subjective and
selected while simply listening.

8

LECTROSONICS, INC.

UHF Digital Hybrid Wireless® Receiver

Supersonic Noise-Based
Dynamic Filter and Squelch

In addition to SmartNR, all hybrid receivers are
equipped with a supersonic noise-based dynamic filter
and squelch system. The incoming audio is monitored
for energy above 22 kHz, pilot tone excepted. Excessive
high frequency energy indicates that the received signal
is too weak to achieve an acceptable signal-to-noise
ratio. Under marginal conditions, a variable low pass
filter is rolled in dynamically, masking the noise while
preserving as much of the transmitted signal as pos­sible. When the channel is too noisy even for the filter,
the audio is squelched.

This noise-based filter and squelch system replaces a
more or less equivalent system used for many years,
which based its operation on RF signal strength. Perfor­mance of the two systems is virtually identical, but the
noise-based system requires no calibration and there
is no better way to track the signal-to-noise ratio than to
measure it directly.

RF-Controlled Digital Noise Filter

In extremely weak signal conditions, an RF sensitive
variable frequency filter is applied to reduce the high
frequency response of the receiver. 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.

Audio Output Level

A setup screen is provided for adjusting the audio out­put level in 1 dB increments from -50 to +5 dBu using
the front panel SEL Up and Down buttons.

Test Tone

To assist in matching the audio levels of equipment con­nected to the UCR401, a 1 kHz audio test tone, adjust­able from -50 to +5 dBu in 1 dB increments, is available
at the XLR connector. This tone is available through the
TONE display window.

Batteries

The UCR401 operates on two AA 1.5 Volt alkaline,
lithium or NiMH batteries. Access to the battery com­partment is gained by lifting one end and turning the
rear panel door.

Note: Do not mix battery types in the same unit.
Also, standard or “heavy duty” batteries are not
recommended.

Power Supply

The UCR401 may be operated from an external DC
power source. The power supplies are protected from
damage to the receiver that could occur if a positive
ground power source is applied.

LCD Display

The display has four primary windows. Pressing the
Front Panel MENU button steps 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 other
user settings. These settings are retained even if the
batteries are removed. After five minutes of no key ac­tivity, the LCD backlight goes off and the display reverts
back to the main window.

Power Up Sequence

The power up sequence consists of four messages that
appear automatically after the power is switched on.

1) UCR401
BLK xx (xx is the frequency block number)

2) VERSION
R.R/A.A (R.R is the RF board firmware version,
A.A is the audio board firmware version)

3) COMPAT
mode (mode is one of the following:
400 - Native 400 Series mode
100 - Lectro 100 Series compatibility
200 - Lectro 200 Series compatibility
MODE 3 - compatible with certain
non-Lectrosonics transmitters)
IFB - compatible with all Lectrosonics IFB
transmitters.
MODE 6 - compatible with certain
non-Lectrosonics transmitters)

4) TUNING
mode (mode is one of the following:
NORMAL - tune in single channel increments
GRP x - tune in precoordinated intermod-free
frequencies (x is A, B, C, D, U or V))

The Main Window appears after the introductory mes­sages are displayed.

The UCR401 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.

Power Off

When the Front Panel Power ON/OFF switch is moved
to the OFF position, the audio output is instantly muted
(squelched) and the message “POWERING OFF...” is
displayed briefly before the receiver switches off.

Rio Rancho, NM

9