Lectrosonics LR Users Manual
LR
Compact Wireless Receiver
INSTRUCTION MANUAL
Digital Hybrid Wireless
US Patent 7,225,135
Fill in for your records:
Quick Start Summary
1) Install receiver batteries (p.8).
2) Select frequency step size in the receiver (p.12).
3) Select the compatibility mode in the receiver (p.12).
4) Find a clear operating frequency (p.12,13).
5) Set up transmitter to match receiver (p.14).
6) Adjust transmitter input gain (p.14).
7) Adjust receiver audio output level for the connected
device (p.15).
®
Serial Number:
Purchase Date:
Rio Rancho, NM, USA
www.lectrosonics.com
LR
2
LECTROSONICS, INC.
Table of Contents
Introduction ............................................................................4
Three Block Tuning Range ...................................................4
RF Front-End with Tracking Filter .........................................4
IF Amplifiers and SAW Filters ..............................................4
Digital Pulse Counting Detector ...........................................4
DSP-Based Pilot Tone ..........................................................4
SmartSquelch™ ...................................................................5
SmartDiversity™ ..................................................................5
Turn On and Turn Off Delays................................................5
Test Tone .............................................................................. 5
LCD Display .........................................................................5
Smart Noise Reduction (SmartNR™) ...................................5
Panels and Features ..............................................................6
IR (infrared) Port ..................................................................6
Balanced Audio Output ........................................................6
Antenna Inputs .....................................................................6
Battery Compartment...........................................................6
USB Port ..............................................................................6
Keypad and LCD Interface ...................................................7
Battery Status and RF Link LED Indicators .........................7
LCD Main Window ...............................................................8
Installing Batteries ................................................................8
Navigating the Menus ...........................................................9
About Frequency Blocks ......................................................9
LCD Menu Tree .....................................................................10
Menu Item Descriptions ......................................................11
The Power Menu ..................................................................11
System Setup Procedures ..................................................12
Firmware Update .................................................................15
Antenna Orientation ............................................................15
Accessories .........................................................................16
Specifications ......................................................................17
Service and Repair ..............................................................18
Returning Units for Repair .................................................18
Compact Portable Receiver
FCC Notice
NOTE: This equipment has been tested and found to comply with the limits for a Class
B digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. The
equipment generates, uses and can radiate radio frequency energy and, if not installed
and used in accordance with the instructions, may cause harmful interference to radio
communications. However, there is no guarantee that interference will not occur in a
particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is
encouraged to try to correct the interference by one or more of the following measures:
• Reorient or relocate the receiving antenna
• Increase the separation between the equipment and receiver
• Connect the equipment into an outlet on a circuit different from that which the
• Consult the dealer or an experienced radio/TV technician for help
Changes or modifications to this equipment not expressly approved by Lectrosonics, Inc.
could void the user’s authority to operate it.
Rio Rancho, NM
receiver is connected
3
LR
TUNING RANGE
Introduction
Three Block Tuning Range
The LR receiver tunes across a range of over 76 MHz.
This tuning range covers three standard Lectrosonics
frequency blocks. See page 9 for more information.
BLOCK
Four tuning ranges are available covering standard
blocks as follows:
Range Blocks Covered
A1 470, 19, 20
B1 21, 22 23
C1 24, 25, 26
D1 27, 28, 29
To simplify backward compatibility with earlier Digital
Hybrid Wireless® equipment, block numbers are presented along with frequencies in LCD screens.
BLOCK
RF Front-End with Tracking Filter
A wide tuning range is helpful in finding clear frequencies for operation, however, it also allows a greater
range of interfering frequencies to enter the receiver.
The UHF frequency band, where almost all wireless
microphone systems operate, is heavily populated
by high power TV transmissions. The TV signals are
immensely more powerful than a wireless microphone
transmitter signal and will enter the receiver even when
they are on significantly different frequencies than the
wireless system. This powerful energy appears as
noise to the receiver, and has the same effect as the
noise that occurs with extreme operating range of the
wireless system (noise bursts and dropouts). To alleviate this interference, front-end filters are needed in the
receiver to suppress RF energy below and above the
operating frequency.
The LR receiver employs a variable frequency, tracking filter in the front-end section (the first circuit stage
following the antenna). As the operating frequency is
changed, the filters re-tune to stay centered over the
selected carrier frequency.
BLOCK
IF Amplifiers and SAW Filters
The first IF stage employs two 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 deliver maximum image rejection. Since these filters are made of
quartz, they are very temperature stable.
The signal is converted to 243.950 MHz in the first
mixer stage, then passed through two SAW filters. After the SAW filter, the IF signal is converted to 250 kHz
and then the majority of the gain is applied. Although
these IF frequencies are unconventional in a wide
deviation (±75 kHz) system, the design provides excellent image rejection.
Digital Pulse Counting Detector
Followign the IF section, the receiver uses an elegantly
simple, yet highly effective digital pulse counting
detector to demodulate the FM signal to generate the
audio, rather than a conventional quadrature detector.
This unusual design eliminates thermal drift, improves
AM rejection, and provides very low audio distortion.
The output of the detector is fed to the microprocessor
where a window detector is employed as part of the
squelch system.
DSP-Based Pilot Tone
The Digital Hybrid system design uses a DSP generated ultrasonic pilot tone to reliably mute the audio
when no RF carrier is present. The pilot tone must be
present in conjunction with a usable RF signal before
the audio output will be enabled. 256 pilot tone frequencies are used across each 25.6 MHz block within
the tuning range of the system. This alleviates erroneous squelch activity in multichannel systems where a
pilot tone signal can appear in the wrong receiver via
IM (intermodulation).
Pilot tones are also provided for legacy equipment and
some models from other manufacturers.
Note: This description applies only to the Digital
Hybrid mode. In Lectrosonics 200 Series, IFB
and Mode 6 compatibility, only one pilot tone
frequency is used on all frequencies, emulating
the original crystal-based system. In other
compatibility modes, no pilot tone is used.
BLOCK
In the front-end circuitry, a tuned filter is followed by an
amplifier and then another filter to provide the selectivity needed to suppress interference, yet provide a
wide tuning range and retain the sensitivity needed for
extended operating range.
4
BLOCK
BLOCK
LECTROSONICS, INC.
Compact Portable Receiver
SmartSquelch
A DSP-based algorithm named SmartSquelchTM optimizes the receiver performance in very weak signal conditions. The RF level and supersonic noise in the audio
are continuously monitored to determine the appropriate
noise reduction needed and the point at which squelch
(complete muting of the audio) is necessary.
As the RF level decreases and supersonic noise in the
signal begins to increase, a variable knee, high frequency
roll-off filter is applied to suppress high frequency noise.
The filtering action moves in and out smoothly to avoid
abrupt changes that could be audible. When the RF
signal becomes so weak that the receiver can no longer
deliver usable audio, the squelch will activate.
SmartDiversity
Microprocessor controlled antenna phase combining
is used for diversity reception. The firmware analyzes
RF level, the rate of change of RF level and the audio
content to determine the optimum timing for phase
switching and the optimum antenna phase. The system
also employs “opportunistic switching” to analyze and
then latch the phase in the best position during brief
squelch activity.
™
™
Turn On and Turn Off Delays
A brief delay is applied when the receiver is powered
up or down to prevent audible noise such as a thump,
pop, click or other transient noise.
Test Tone
To assist in matching the audio levels of equipment
connected to the receiver, a 1 kHz audio test tone generator is provided, with an output level adjustable from
-50 to +5 dBu in 1 dB increments.
The tone simulates the audio output with a steady signal at full modulation, making it easy to adjust the level
to precisely match the optimal level for the connected
device and maximize the signal to noise ratio of the
system.
LCD Display
Setup and monitoring is done through the LCD display
on the control panel. The LCD image can be inverted
as desired for personal preference or maximum visibility in direct sunlight. The built-in backlight for viewing
in dimly lit environments can be set to remain on for 30
seconds, 5 minutes or to remain on constantly.
Smart Noise Reduction (SmartNR™)
Note: The SmartNR setting is user selectable
only in the Digital Hybrid compatibility 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 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 bias resistor of
many electret lavaliere mics is –119 dBV and the noise
level of the microphone’s electronics is even higher. In
order to reduce this noise the receiver is equipped with
a “smart” noise reduction algorithm called SmartNR®,
which removes hiss without sacrificing audio high
frequency response.
SmartNR® works by attenuating only those portions of
the audio signal that fit a statistical profile for randomness or “electronic hiss.” Because it is much more than
a sophisticated variable low pass filter, the transparency of the audio signal is preserved. 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. The
optimal setting for each application is subjective and is
normally selected while simply listening.
• OFF defeats noise reduction 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 output.
• NORMAL applies enough noise reduction to
remove most of the hiss from the microphone
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.
• FULL applies enough noise reduction to remove
most of the hiss from nearly any signal source of
reasonable quality and some high frequency environmental noise, assuming the input gain is set
properly at the transmitter.
Rio Rancho, NM
5
LR
Panels and Features
Belt clip
mounting
hole
USB Port
CAN ICES-3 (B)/NMB-3(B)
Model: LR-XX Made in the USA
Serial No. XXXXX
Frequency block XXX (XXX.X - XXX.X MHz)
This device complies with part 15 of the FCC rules.
Operation is subject to the condition that this device
does not cause harmful interference.
CAN RSS-Gen/CNR-Gen
IR (infrared)
Port
IR PORT
Balanced Audio
Antenna Inputs
AUDIO
OUT
Output
Battery polarity
IR (infrared) Port
Settings for compatibility mode and frequency can be
transferred from the receiver via this port to an IR enabled transmitter to simplify setup. The receiver is used
to scan for a clear frequency, and the new frequency
can be sent to the transmitter via the IR ports.
Balanced Audio Output
Balanced or unbalanced audio from mic to line level
is provided on the TA3 output jack; adjustable in 1 dB
steps from -50 dBu to +5 dBu.
6
Battery
Compartment
Door
Antenna Inputs
Two standard 50 ohm SMA connectors can be used
with whip antennas or coaxial cable connected to
remote antennas.
Battery Compartment
Two AA batteries are installed as marked on the rear
panel of the receiver. The battery door is hinged and
remains attached to the housing.
USB Port
Firmware updates are made easy with the USB port
on the side panel.
LECTROSONICS, INC.
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