Lectrosonics UCR201 User Manual

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UCR2

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DIVERSITY UHF RECEIVER

OPERATING INSTRUCTIONS

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Professional Audio Products Since 1971

Rio Rancho, NM

www.lectrosonics.com

UCR201

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Professional Audio Products Since 1971

UHF Wireless Diversity Receiver

TABLE OF CONTENTS

GENERAL TECHNICAL DESCRIPTION .................................................................. 4

INTRODUCTION ................................................................................................ 4

SMART DIVERSITY™ ........................................................................................ 4

RF MODULE....................................................................................................... 4

DOUBLE BALANCED DIODE MIXERS .......................................................... 4

SURFACE ACOUSTIC WAVE (SAW) FILTER ................................................. 5

DIGITAL PULSE COUNTING DETECTOR ..................................................... 5

TRI MODE DYNAMIC FILTER .................................................................................. 5

PILOT TONE MUTE........................................................................................... 5

SMART SQUELCH™ ......................................................................................... 5

OUTPUT LEVEL ADJUST .................................................................................. 5

POWER SUPPLY ................................................................................................ 5

LCD..................................................................................................................... 6

POWER UP SEQUENCE ................................................................................... 6

POWER OFF SEQUENCE ................................................................................. 6

FRONT PANEL CONTROLS AND INDICATORS .................................................... 7

LCD SCREEN..................................................................................................... 7

MENU BUTTON.................................................................................................. 7

REAR PANEL FEATURES ....................................................................................... 7

XLR AUDIO OUTPUT JACK ............................................................................... 7

POWER INPUT JACK ........................................................................................ 7

SELECT UP/DOWN BUTTONS.......................................................................... 7

POWER ON/OFF SWITCH................................................................................. 7

MAIN WINDOW (LCD) .............................................................................................. 8

MENU SELECTIONS FROM MAIN WINDOW.......................................................... 9

FREQUENCY WINDOW ..................................................................................... 9

BATTERY LEVEL WINDOW ............................................................................... 9

SETUP WINDOW ............................................................................................... 9

LEVEL ............................................................................................................. 9

TONE .............................................................................................................. 9

TXBAT ............................................................................................................. 9

FREQUENCY SCAN MODE ................................................................................... 10

ANTENNA USE AND PLACEMENT ...................................................................... 11

INSTALLATION AND OPERATING INSTRUCTIONS ............................................ 12

FINDING CLEAR FREQUENCIES ................................................................... 12

LOCKING AND UNLOCKING THE UCR201 FRONT PANEL CONTROLS ..... 13

REPLACING THE BATTERY .................................................................................. 14

UCR201 REPLACEMENT PARTS and ACCESSORIES ....................................... 15

TROUBLESHOOTING ............................................................................................ 16

SPECIFICATIONS AND FEATURES ..................................................................... 17

SERVICE AND REPAIR .......................................................................................... 18

RETURNING UNITS FOR REPAIR ........................................................................ 18

Rio Rancho, NM – USA

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UCR201

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GENERAL TECHNICAL DESCRIPTION

INTRODUCTION

The UCR201 is a portable, high performance, triple­conversion, frequency synthesized, UHF receiver fully
compatible with all Lectrosonics 200 series transmitters.
The RF performance is extremely stable over a very
wide temperature range, making the UCR201 perfectly
suited to the rough environmental conditions found in the
field. The proprietary audio processing includes a dual­band 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 UCR201 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

Diversity™ effectively minimizes dropouts in situations
where multi-path reflections can cause serious
problems.

RF MODULE

The UCR201 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 UCR201 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 UCR201 uses a low noise GaAs mixer
having a robust 3rd 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

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RF MODULE

ANTENNA

SWITCHING

L C D

D i s p l a y

P a n e l

Smart Diversity

FILTER

SYNTHESIZER

UCR201

SAW

FILTER

244 MHz

IF AMP

AMP

u P

FILTER

LC

Filter

2

E PROM

1st

VCO

Smart Squelch

Attenuation

2nd

VCO

FILTER

IF

FILTER

2ND

MIXER

10.7 MHZ

HI-LEVEL

MIXER

CONTROLLED

OSCILLATOR

Professional Audio Products Since 1971

3RD MIXER

AND

IF AMP

XTAL

3rd

PILOT TONE

DETECTOR

COUNTING
DETECTOR

50KHz

LP FILTER

23 KHZ

LP

FILTER

VARIABLE

CUT-OFF

LP FILTER

EXPANDER

EXPANDER

BLOCK DIAGRAM

2:1

TREBLE

AUDIO

AMP

2:1

BASS

Output

Level

Adjust

Digital

Attenuator

Squelch

Digital

Squelch

XLR
OUT

50

2 (HI)

2K

1 (COMMON

2K

3 (LO)

50

UHF Wireless Diversity Receiver

SURFACE ACOUSTIC WAVE (SAW) FILTER

A state-of-the-art SAW filter on the 244 MHz IF amplifier
offers sharp skirts, constant group delay, and wide
bandwidth in one filter. Though expensive, this special
type of filter allows primary filtering as early as possible,
at as high a frequency as possible and before high gain
is applied to the signal. Since these filters are made of
quartz, they are very temperature stable. (Conventional
LC filters at these frequencies don’t begin to perform as
well and in addition would drift unacceptably in the
elevated temperatures of an equipment rack or in the
field where temperatures are in constant flux.) After the
SAW filter, the 244MHz 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. 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 to produces an
excellent noise improvement at low signal strengths
(capture ratio).

DIGITAL PULSE COUNTING DETECTOR

The UCR201 receiver uses an advanced digital pulse
detector to demodulate the FM signal, rather than a
conventional quadrature detector. The common problem
with quadrature detectors is thermal drift, particularly
those that operate at higher frequencies like 10.7 MHz.

The UCR201 design presents an elegantly simple, yet
highly effective solution to this age old problem. A
stream of precision pulses is generated at 300kHz and
locked to the FM signal coming from the 300 kHz IF
section. The pulse width is constant, but the timing
between pulses varies with the frequency shift of the FM
signal. The integrated voltage of the pulses within any
given time interval varies in direct proportion to the
frequency modulation of the radio signal. Another way of
describing it is that as the FM modulation increases the
frequency, the circuit produces more pulses and as the
modulation decreases the frequency, the circuit
produces fewer pulses. More pulses produce a higher
voltage and fewer pulses a lower voltage. The resultant
varying voltage is the audio signal.

This type of detector eliminates the traditional problems
with quadrature detectors and provides very low audio
distortion, high temperature stability and stable audio
level. The counting detector also adds additional AM
rejection. Since the detector pulse amplitudes are
constant, level differences in the IF signal do not affect
them.

TRI MODE DYNAMIC FILTER

The detected audio signal is passed through a “dynamic
noise reduction circuit,” which automatically adjusts the
filter’s cutoff frequency by measuring the amplitude and
frequency of the audio signal and the quality of the RF
signal. The audio bandwidth is held only to that point

necessary to pass the highest frequency audio signal
present at the time. If the RF level is weak, then the filter
becomes more aggressive. This results in a dramatic
reduction of “hiss” at all times. During passages with a
high frequency content, this filter gets completely “out of
the way” and passes the signal with no decrease in high­frequency response.

PILOT TONE MUTE

The UCR201 uses a pilot tone muting technique in order
to protect against the reception of stray signals. The
Lectrosonics transmitter adds an inaudible signal, known
as the pilot tone, to the transmitted signal. The receiver
detects (and removes) the pilot tone, and is thus able to
identify the desired signal and mute all others.

When the receiver is powered up, receive audio is muted
unless a proper pilot tone is detected. The pilot tone
must be present for approximately one second before
the signal is accepted.

A PILOT TONE BYPASS mode is available. In this
mode, the received audio remains unmuted regardless of
the presence or absence of a pilot tone. This mode is
useful for locating a clear frequency, since any potential
interference may be heard. Because this mode disables
the squelch, it may also be used in situations where
squelching behavior is undesirable.

SMART SQUELCH™

The UCR201 employs a sophisticated squelching system
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 are cut off.

SmartSquelchTM achieves an optimal balance of these
trade-offs by combining several techniques that remove
distracting noise without the squelching action itself
becoming a distraction. Thse include: waiting for a
complete word or syllable before squelching, assessing
recent squelching history and RF signal strength and
assessing audio content to determine available masking.

By adjusting squelching behavior dynamically for the
optimal result under varying conditions, the receiver can
deliver acceptable audio quality from otherwise unusable
signals.

OUTPUT LEVEL ADJUST

Convenient front panel controls allow adjusting the audio
output in 1dB steps from -50 to +9 dBu.

POWER SUPPLY

The UCR201 may powered by a 9 VDC battery, or from
an external DC source (see Specifications and Features
section for allowed voltages.) A built in Poly-Fuse

Rio Rancho, NM – USA

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UCR201

protects the unit when an external power source is used.
This fuse resets if the power supply is disconnected for
15 seconds or longer.

LCD

The front panel LCD offers four primary windows.
Pressing the MENU button rotates through each of these
windows.

If the battery gets low on either the UCR201 or the
associated transmitter, a message will interrupt the
display every few seconds stating “LOW RX BATTERY”
or “LOW TX BATTERY.”

Regardless of which window or setup screen is active
during operations, after power is removed, the unit
defaults to the Main Window and to the most recent
frequency and audio settings. These settings are
retained even if the battery is removed.

The display backlight is always on when the unit is
plugged into an external power source. It will turn off
after five minutes if no keypress activity is detected when
operating on the internal battery.

POWER UP SEQUENCE

It takes about two seconds after the UCR201 is initially
turned on for it to become fully operational; however,
audio will pass through during the start up phase if there
is an active transmitter on the same frequency as the
UCR201.

At power-up, the LCD will automatically scroll through a
series of messages to confirm proper operation and
inform you of its state. First it will show if the unit is
LOCKED or UNLOCKED. (See LOCKING AND
UNLOCKING THE UCR201) Following messages will
state Lectrosonics (we like our name), UCR201, the
firmware revision of the internal programming and the
frequency block assigned to the receiver. The Main
Window displays after these introductory messages.

Note

UCR201s with Firmware Verson 4.1 or later have a

quick tune shortcut. See Menu Selections From Main

Window, Frequency Window for details.

POWER OFF SEQUENCE

When the unit is turned off, the audio output is instantly
muted (squelched) and a window displays “POWERING
OFF” just before actually switching off the power.

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Professional Audio Products Since 1971