Lectrosonics R400 User Manual
R400
UHF DIVERSITY
RECEIVER
(Includes IFB Mode)
Featuring Digital Hybrid Wireless
™
Technology
(US Patent Pending)
OPERATING INSTRUCTIONS
Rio Rancho, NM, USA
www.lectrosonics.com
R400
2
Portable Wireless Sound System
The Lectrosonics Digital Hybrid WirelessTM (US Patent Pending) 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 (Digital Signal Processor) 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. Unlike traditional analog compandor systems, no artifacts are introduced under strong RF conditions.
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.
TABLE OF CONTENTS
GENERAL TECHNICAL DESCRIPTION ...................................................................................................... 4
INTRODUCTION ............................................................................................................................................................ 4
DIVERSITY RECEPTION .............................................................................................................................................. 4
RF FRONT-END AND MIXER ........................................................................................................................................ 4
FREQUENCY TUNING GROUPS ................................................................................................................................. 4
MICROPROCESSOR, PLL AND VCO CIRCUITS ........................................................................................................ 4
IF AMPLIFIERS AND SAW FILTERS ............................................................................................................................. 5
DIGITAL PULSE COUNTING DETECTOR .................................................................................................................... 5
DIGITAL SIGNAL PROCESSOR.................................................................................................................................... 5
COMPATIBILITY MODES ............................................................................................................................................... 5
DSP-BASED PILOT TONE ............................................................................................................................................. 5
SMART SQUELCH™ ..................................................................................................................................................... 5
SMART NOISE REDUCTION (SmartNR™) .................................................................................................................. 5
LCD SCREEN ................................................................................................................................................................ 6
POWER SUPPLY ........................................................................................................................................................... 6
FRONT PANEL CONTROLS AND FUNCTIONS ......................................................................................... 7
LCD SCREEN ................................................................................................................................................................ 7
POWER/PREV MENU BUTTON .................................................................................................................................... 7
REAR PANEL FEATURES ............................................................................................................................ 7
BAL AUDIO OUTPUT JACK .......................................................................................................................................... 7
PUSH FOR MENU/ROTATE TO SELECT CONTROL ................................................................................................... 7
POWER INPUT JACK .................................................................................................................................................... 7
MAIN ANT and DIV ANT ................................................................................................................................................ 7
R400 MENU SELECTIONS ........................................................................................................................... 8
MENU FUNCTIONS ....................................................................................................................................................... 9
SetUpRx .................................................................................................................................................................... 9
Freq ........................................................................................................................................................................ 9
Level ....................................................................................................................................................................... 9
Tuning ..................................................................................................................................................................... 9
Compat ................................................................................................................................................................... 9
Tone ........................................................................................................................................................................ 9
PilotBP .................................................................................................................................................................... 9
Phase ..................................................................................................................................................................... 9
TxBatt ................................................................................................................................................................... 10
SmartNR ............................................................................................................................................................... 10
BACK .................................................................................................................................................................... 10
LockSet .................................................................................................................................................................... 10
SmrtTun (Firmware version 1.5 and later) ............................................................................................................... 10
Scan ......................................................................................................................................................................... 10
ANTENNA USE AND PLACEMENT ........................................................................................................... 12
INSTALLATION AND OPERATING INSTRUCTIONS ............................................................................... 13
PROGRAMMING USER GROUPS .............................................................................................................................. 13
ADDING USER GROUP FREQUENCIES .............................................................................................................. 14
ERASING USER GROUP FREQUENCIES ............................................................................................................ 14
R400 REPLACEMENT PARTS AND ACCESSORIES .............................................................................. 15
Compatible Frequency Chart ........................................................................................................................................ 16
Frequency Coordination ............................................................................................................................ 16
Rule No. 1 ................................................................................................................................................................ 16
Rule No. 2 ................................................................................................................................................................ 18
Rule No. 3 ................................................................................................................................................................ 18
Using the Scan Function .............................................................................................................................................. 18
Call Lectrosonics .......................................................................................................................................................... 18
TROUBLESHOOTING ................................................................................................................................. 19
SPECIFICATIONS AND FEATURES .......................................................................................................... 21
SERVICE AND REPAIR ............................................................................................................................... 22
RETURNING UNITS FOR REPAIR ............................................................................................................. 22
LIMITED ONE YEAR WARRANTY .............................................................................................................. 24
Rio Rancho, NM – USA
3
R400
GENERAL TECHNICAL DESCRIPTION
INTRODUCTION
The R400 is a high performance, triple-conversion,
frequency synthesized UHF receiver fully compatible
with all Lectrosonics 400 Series Digital Hybrid Wireless
TM
transmitters, 200 and 100 Series analog transmitters,
plus analog transmitters from other manufacturers (call
Lectrosonics for details). The R400 features 256 user
selectable frequencies and its proprietary audio processing includes a digital signal processor (DSP) for very low
distortion and a superior signal to noise ratio with audio
output adjustable from -50 dBu to +5 dBu in 1 dB increments.
The R400 features a menu-driven LCD graphic display,
a pushbutton POWER/PREV MENU control and a dual
function (push/rotate) PUSH FOR MENU/ROTATE TO
SELECT control (hereafter called the MENU control) as
a convenient means of viewing and altering user settings. For example, the Main Window displays the pilot
tone indicator, antenna diversity phase, RF level, audio
level, operating frequency, transmitter Frequency Select
Switch settings and transmitter battery status.
The MENU control provides simple and intuitive access
to change and adjust settings and operating levels.
Pushing the MENU control from the Main Window enters
the Top Menu which displays a choice of four submenu
selections: SetUpRx, LockSet, Scan, and Exit. Each
subsequent push of the MENU control moves into
another menu layer. Rotating the MENU control either
selects a submenu or sets a functional parameter.
DIVERSITY RECEPTION
SMART DiversityTM 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.
RF FRONT-END AND MIXER
The R400 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 R400 has a front-end section
that tunes to the desired frequency band and rejects or
“tunes out” unwanted out of band signals. Two tuned HIQ 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. The
first mixer uses new GaAs technology that 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.
FREQUENCY TUNING GROUPS
The R400 provides four "factory set" compatible frequency groups (A through D) and two user programmable frequency groups (U and V).
The factory groups have been selected to avoid intermodulation problems. Each group includes eight frequencies.
The user programmable frequency groups can have up
to 16 frequencies per group.
MICROPROCESSOR, PLL AND VCO CIRCUITS
An 8-bit microprocessor 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 power voltages. The microprocessor
also drives the LCD display, controls the squelch and
audio output attenuator, and operates the PLL/VCO
circuits and the antenna phase switch.
RF MODULE
ANTENNA
COMBINING
LCD
Display
Panel
Smart Diversity
FILTER
PLL
SYNTHESIZER
PILOT TONE
DETECT
Attenuation
CERAMIC
FILTER
2ND
MIXER
10.7 MHZ
HI-LEVEL
MIXER
SAW
FILTER
244 MHz
IF AMP
SAW
FILTER
244 MHz
IF AMP
AMP
FILTER
uP
Filter
2
E PROM
LC
VCO
1st
2nd
VCO
FILTER
XTAL
CONTROLLED
3rd
OSCILLATOR
3RD MIXER
AND
IF AMP
COUNTING
DETECTOR
50KHz
LP FILTER
A-D
CONVERTER
DIGITAL SIGNAL
PROCESSOR
D-A
CONVERTER
R400
BLOCK DIAGRAM
Output
Level
Adjust
AUDIO
AMP
Digital
Attenuator
XLR
OUT
50
2 (HI)
5K
1 (COMMON)
5K
3 (LO)
50
4
Portable Wireless Sound System
IF AMPLIFIERS AND SAW FILTERS
The first IF low noise amplifier is controlled with feedback regulation and drives a quartz SAW (Surface
Acoustical Wave) filter. The 244 MHz SAW filter combines sharp tuning, constant group delay, wide bandwidth and excellent temperature stability, far superior to
conventional LC filters. The second mixer converts the
244 MHz first IF signal down to 10.7 MHz. The second
IF is filtered through two ceramic filters for sharp selectivity, then converted down to 300 kHz and fed to the
Digital Pulse Counting Detector.
DIGITAL PULSE COUNTING DETECTOR
The R400 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. The
output from the Digital Pulse Counter is an analog signal
containing the digital audio information. This signal is
fed through a low pass filter to an A-D Converter in the
Digital Signal Processing section.
DIGITAL SIGNAL PROCESSOR
The DSP reconstructs the original digitized audio from
the A-D Converter and detects the ultrasonic Pilot Tone
used to control the receiver's squelch (only in 400 Series
and 200 Series Compatibility Mode with the Pilot Tone
enabled – see DSP-Based Pilot Tone).
The DSP also incorporates an RF-controlled digital
noise filter (in addition to SmartNR™). This RF sensitive
variable frequency filter reduces high frequency response under extremely weak RF conditions. The 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.
The reconstructed original analog audio signal is then
sent to the audio output section.
COMPATIBILITY MODES
The R400 receiver was designed to compatible with
Lectrosonics 400 Series transmitters and will yield the
best performance when doing so. However, due to the
flexibility of digital signal processing, the R400 is also
able to operate with Lectrosonics 200 Series,
Lectrosonics 100 Series, IFB and certain nonLectrosonics transmitters in special compatibility modes.
(Contact the Lectrosonics Sales Department for a
complete list of compatible transmitters.)
DSP-BASED PILOT TONE
The 400 Series system design uses a DSP generated
ultrasonic pilot tone from the transmitter to control the
receiver audio muting (squelch). If the Pilot Tone is
enabled, a Pilot Tone Detect signal generated by the
DSP automatically controls the receiver's squelch. Built-
in brief delays are incorporated to eliminate the thumps,
pops or other transients that can occur when the transmitter 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. Using the
DSP to detect the 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.
The above 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
The R400 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 R400
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 R400 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.
Note
™
SMART NOISE REDUCTION (SmartNR™)
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 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 R400 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.”
SmartNR™ offers significantly increased transparency
over the sophisticated variable low pass filters used in
Rio Rancho, NM – USA
5
R400
previous designs. 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: Off, Normal and
Full.
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.
NORMAL (factory default) - 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.
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.
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
Note
adjustable.
LCD SCREEN
The LCD screen is used in conjunction with the MENU
control to change and control the operational settings,
and also provide a visual feedback of overall system
operation. (See FRONT PANEL MENU SELECTIONS.)
POWER SUPPLY
The R400 is operated from an external DC power source
with a range of +8 VDC to +18 VDC, up to 0.20 amperes
(200 milliamps) maximum. The receiver has a built-in
Poly-Fuse to protect the unit. If a problem occurs that
trips this fuse, it will reset after the power supply is
disconnected for about 15 seconds. The power input
section also has built-in protection circuits that prevent
damage to the receiver if a positive ground power source
is applied.
The R400 requires external DC power and has no provisions for
Note
internal batteries.
6
Portable Wireless Sound System
FRONT PANEL CONTROLS AND FUNCTIONS
LCD Screen
POWER/PREV MENU Button
LCD SCREEN
The LCD Screen is a graphics-type Liquid Crystal
Display that is used to monitor system operation and, in
conjunction with the MENU control, to configure the
R400. (See R400 MENU SELECTIONS.)
POWER/PREV MENU BUTTON
Dual function control providing a POWER On/Off function and a return to previous menu function. If the
receiver is turned off, momentarily pressing this button
turns the receiver on. If the receiver is already turned
REAR PANEL FEATURES
MENU Control
on, pressing this button causes the LCD to display the
previous menu. Pressing and holding the button for at
least two seconds turns the unit off.
PUSH FOR MENU/ROTATE TO SELECT CONTROL
The dual function MENU control is used to access
menus and select menu functions or receiver configuration. Push the control to enter the TopMenu, or activate
the selected menu option. Rotate the control to either
select a submenu or to set an operating parameter.
MAIN ANT
Power Input Jack
BAL AUDIO OUTPUT JACK
This is a standard XLR configuration with Pin 2 “positive”
with reference to hand-held and plug-on transmitters.
With lavaliere microphones and belt-pack transmitters,
however, phase will vary with different types of microphones (2-wire vs. 3-wire for example). The audio output
is balanced but not floating. An unbalanced signal is
available using Pin 1 as ground, Pin 2 as signal and
leaving Pin 3 open.
Rio Rancho, NM – USA
BAL AUDIO OUT
DIV ANT
POWER INPUT JACK
The power input jack accepts +8 VDC to +18 VDC
(center pin is positive and sleeve is ground). The input is
diode protected to prevent damage if the power is
applied with reversed polarity, but the unit will not operate until the condition is fixed.
MAIN ANT and DIV ANT
The MAIN ANT and DIV ANT inputs are both 50 Ohm,
BNC connectors. In single antenna configurations, the
antenna is connected to the MAIN ANT jack. (See
ANTENNA USE AND PLACEMENT.)
7
R400
Main Window
P
R400
1000
100
10
1uV
557.100
NORM
40
20
R400 MENU SELECTIONS
C3
0
R400 Menu Map
TopMenu SetUpRx
Main Window
Return to
LockSet
SmrtTun
Scan
xExit
SetUpRx
LockSet
SmrtTun*
Scan
Exit
LockSet
NOT LOCKED
SmartTuning
in progress...
Freq Scan
Window
Coarse
Scan Scroll
Fine
Scan Scroll
Return to Top Menu
Freq
Level
Tuning
Compat
Tone
PilotBP
Phase
TxBatt
SmartNR
BACK
Freq
NORMAL
557.100 MHz
Level
+00 dBu
To ne
+00 dBu
PilotBP
NORMAL
Phase
NORMAL
TxBatt
9V LTH
0.0V
SmartNR
NORMAL
TV28
C3
*Firmware Version 1.5 and above
MAIN WINDOW DISPLAY
Icon Description
Compat
400 Series
Compat
200 Series
Compat
100 Series
Compat
Compat
MODE 3
IFB*
Tuning
Tuning
Fact Grp A
Tuning
Fact Grp B
Tuning
Fact Grp C
Tuning
Fact Grp D
Tuning
User Grp U
Tuning
User Grp V
Normal
P
40
557.100
NORM
20
C3
Pilot tone indicator - A steady “P” is displayed when the transmitter pilot tone is present (200 Series
and the native 400 Series Compatibility Modes only). The icon flashes if no pilot tone is detected and
changes to a small “b” if the pilot tone has been bypassed. To bypass the pilot tone, from the Main
Window, push the MENU control twice to select SetUpRx, then rotate the control to select PilotBP.
Push the MENU control again and rotate it to highlight BYPASS. Push the POWER/PREV MENU
button several times to return to the Main Window.
Antenna Phase indicator - Displays antenna phase switching activity. As the DIV ANT phase is
switched, the symbol will flip vertically.
RF level - Displays the relative strength of the incoming RF. The icon grows taller as the strength of
the incoming RF signal increases. RF level calibrations are shown from 1 uV to 1000uV on the bezel
to the left of the RF level icon.
Audio Level - The audio level bar changes in size horizontally to indicate the audio level (modula-
0
tion) of the signal received from the transmitter. The bar display will show a vertical bar at the right
end when the audio signal is in limiting (maximum level) at the transmitter. Calibration marks in dB
are displayed below the bar.
Battery Level - Indicates the transmitter battery status or the transmitter battery use time, depending
on the TXBAT setting. The transmitter battery status icon is available only in compatibility modes
supporting battery telemetry (400 and 200 Series). In such cases, the transmitter battery status icon
appears 5 to 10 seconds after the transmitter signal is acquired. If selected in the TXBAT setup
screen, the transmitter battery timer is available in any compatibility mode. It accumulates hours and
minutes that the communications link is active, retaining the timing even when the receiver is off.
Operating Frequency/Tuning Mode/Switch Settings - Displays the operating frequency, the tuning
mode and the settings for the Frequency Select Switches in the associated transmitter(s). The
Tuning Mode indicates whether the receiver is set for Normal tuning or Group tuning. (See Tuning
Menu)
8
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