Lectrosonics SMDa User Manual
SMDa
Super Miniature Belt-Pack Transmitters
With Digital Hybrid Wireless™ Technology
US Patent 7,225,135
INSTRUCTION MANUAL
SMDa Dual battery, 100 mW
RM/E Remote Control
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Purchase Date:
Rio Rancho, NM, USA
www.lectrosonics.com
SMDa Series
2
LECTROSONICS, INC.
Thank you for selecting a Lectrosonics SM Series
ultra-miniature transmitter. The unique design provides
specialized features for professional applications:
• Outstanding RF operating range
• Superb audio quality
• Ultra-lightweight, corrosion resistant housing
• Water resistant seals for use in damp environments
• Programmable compatibility modes for use with a
wide variety of different receivers
The Digital Hybrid Wireless® design (US Patent
7,225,135) combines 24-bit digital audio with analog
FM resulting in a system that has the same excellent
operating range, spectral efficiency and long battery life
as analog systems, plus the excellent audio fidelity typical of pure digital systems.
The SMDa Series transmitters use a standard Lectrosonics 5-pin type input jack for use with electret lavaliere mics, dynamic mics, or line level signals. A water
resistant control panel with LCD, membrane switches
and multi-color LEDs make input gain adjustments
and frequency and compatibility mode selection quick
and accurate, without having to view the receiver. The
battery compartment accepts AA lithium or rechargeable batteries. The housing is machined from a solid
aluminum block to provide an extremely lightweight and
rugged package. A special non-corrosive finish resists
salt water exposure and perspiration in extreme environments.
Rio Rancho, NM
Super-Minature Belt Pack Transmitters
Table of Contents
General Technical Description ...............................................4
Wideband Design...................................................................4
Servo Input.............................................................................4
Digital Hybrid Wireless
No Pre-Emphasis/De-Emphasis ............................................4
Low Frequency Roll-Off .........................................................5
Input Limiter ...........................................................................5
Signal Encoding and Pilot Tone .............................................5
Microprocessor, PLL and VCO Circuits..................................5
Compatibility Modes...............................................................5
Wide-Band Deviation .............................................................5
Battery Options and Operating Time .....................................5
Frequency Blocks...................................................................5
Circulator/Isolator...................................................................5
Controls and Functions ..........................................................6
LCD Screen ...........................................................................6
Power LED .............................................................................6
Audio Input Jack.....................................................................6
Battery Compartment and Thumb Screw...............................6
Modulation LEDs....................................................................6
Audio Button ..........................................................................6
Freq Button ............................................................................6
Up/Down Arrows ....................................................................6
Antenna..................................................................................6
Setup with the LCD..................................................................7
Audio Screen .........................................................................7
Frequency Screen..................................................................7
Compatibility Mode Screen....................................................7
Turning the Power On ............................................................7
Turning the Power Off ............................................................7
Entering the Standby Mode ...................................................7
Battery Installation ..................................................................8
Lock/Unlock Screen ...............................................................8
Remote Control Operation.....................................................8
Operating Instructions............................................................9
Power Up and Boot Sequence...............................................9
Power Down...........................................................................9
Standby Mode........................................................................9
Selecting the Compatibility Mode...........................................9
Setting Transmitter Operating Frequency.............................10
Adjusting the Low Frequency Roll-off ..................................10
Attaching a Microphone and Adjusting Gain........................10
Locking or Unlocking the Control Panel ...............................11
Attaching and Removing the Microphone............................11
5-Pin Input Jack Wiring .........................................................12
Installing the Connector: ......................................................12
Microphone Cable Termination
Microphone RF Bypassing...................................................14
Line Level Signals................................................................14
Wiring Hookups for Different Sources ................................15
Compatible Wiring for Servo Bias and Early Inputs .............15
Simple Wiring - Servo Bias Inputs Only ...............................15
RM Remote Control Operating Instructions .......................16
RM Front Panel Controls......................................................16
Powering the RM on and off.................................................16
Principles of Operation.........................................................16
RM Pages ............................................................................16
Operating Notes...................................................................17
RM Quick Reference............................................................17
Troubleshooting.....................................................................18
RM Troubleshooting .............................................................19
Included Accessories............................................................20
Optional Accessories............................................................20
Specifications and Features.................................................21
Service and Repair ................................................................22
Returning Units for Repair ...................................................22
for Non-Lectrosonics Microphones..............................13
®
Technology ......................................4
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SMDa Series
General Technical Description
Wideband Design
Digital Hybrid transmitters use ±50 kHz wide deviation
for an excellent signal to noise ratio and wide dynamic
range. The DSP controlled input limiter features a wide
range dual envelope design which cleanly limits input
signal peaks over 30 dB above full modulation. Switching
power supplies to provide constant voltages to the transmitter circuits from the beginning (1.5 Volts) to the end
(0.85 Volts) of battery life, and an ultra low noise input
amplifier for quiet operation.
Servo Input
The bias voltage in the input is set by a servo loop that
regulates the DC voltage at the microphone to a user
selectable choice of 2 or 4 Volts. The input can handle
mic bias loads from 1uA to 2000uA while still maintaining full bias voltage regulation. The servo loop also
incorporates a filter that causes it to servo out frequencies below 20 Hz and rolls off the response of the
lavaliere itself to wind noise, thumps and breath pops.
These low frequency excursions are stopped right at
the mic FET so they do not overload early audio stages
in the transmitter.
Digital Hybrid Wireless® Technology
US Patent 7,225,135
All wireless links suffer from channel noise to some degree, and all wireless microphone systems seek to minimize the impact of that noise on the desired signal. Conventional analog systems use compandors for enhanced
dynamic range, at the cost of subtle artifacts (known as
“pumping” and “breathing”). Wholly digital systems defeat
the noise by sending the audio information in digital form,
at the cost of some combination of power, bandwidth and
resistance to interference.
No Pre-Emphasis/De-Emphasis
Lectrosonics Digital Hybrid systems overcome channel
noise in a dramatically new way, digitally encoding the
audio in the transmitter and decoding it in the receiver,
yet still sending the encoded information via an analog
FM wireless link. This proprietary algorithm is not a
digital implementation of an analog compandor but a
technique that can be accomplished only in the digital
domain, even though the inputs and outputs are analog.
Channel noise still impacts received signal quality and
will eventually overwhelm a receiver. Digital Hybrid
simply encodes the signal to use a noisy channel as efficiently and robustly as possible, yielding audio performance that rivals that of wholly digital systems, without
the power and bandwidth problems inherent in digital
transmission.
Because it uses an analog FM link, the Digital Hybrid
system enjoys all the benefits of conventional FM wireless systems, such as excellent range, efficient use of
RF spectrum, and resistance to interference. However,
unlike conventional FM systems, it does away with the
analog compandor and its artifacts.
The Digital Hybrid design results in a signal-to-noise ratio
high enough to preclude the need for conventional preemphasis (HF boost) in the transmitter and de-emphasis
(HF roll off) in the receiver. This eliminates the potential
for extreme distortion on signals with abundant highfrequency information.
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LECTROSONICS, INC.
Super-Minature Belt Pack Transmitters
Low Frequency Roll-Off
The low frequency roll-off can be set for a 3 dB down
point at 35, 50, 70, 100, 120 and 150 Hz to control subsonic and very low frequency audio content in the audio. The actual roll-off frequency will vary slightly depending upon the low frequency response of the microphone.
Excessive low frequency content can drive the transmitter into limiting, or in the case of high level sound systems, can even cause damage to loudspeaker systems.
The roll-off is normally adjusted by ear while listening
as the system is operating.
Input Limiter
A DSP-controlled analog audio limiter is employed
before the analog-to-digital (A-D) converter. The limiter
has a range of more than 30 dB for excellent overload
protection. A dual release envelope makes the limiter
acoustically transparent while maintaining low distortion. It can be thought of as two limiters in series, a fast
attack and release limiter followed by a slow attack and
release limiter. The limiter recovers quickly from brief
transients, with no audible side effects, and also recovers slowly from sustained high levels, to keep audio distortion low and while preserving short term dynamics.
Signal Encoding and Pilot Tone
In addition to controlling the limiter, the DSP also encodes the digitized audio from the A-D converter and
adds an ultrasonic pilot tone to control the receiver’s
squelch. A pilot tone squelch system provides a reliable
method of keeping a receiver output muted (squelched)
even in the presence of significant interference. When
the system is operating in the hybrid mode, a different pilot tone frequency is generated for each carrier
frequency to prevent inadvertent squelch problems and
simplify multi-channel coordination.
Microprocessor, PLL and VCO Circuits
A microprocessor monitors user command inputs from
the control panel buttons and numerous other internal
signals. It works intimately with the DSP to ensure the
audio is encoded according to the selected Compatibility Mode and that the correct pilot tone is added to the
encoded signal.
Control Panel
The control panel includes four membrane switches and
an LCD screen to adjust the operational settings. Multicolor LEDs are used to indicate audio signal levels for
accurate gain adjustment and for battery status.
Wide-Band Deviation
±50 kHz deviation improves the signal to noise ratio and
audio dynamic range of a wireless system dramatically.
Wide deviation combined with a high powered transmitters makes a significant improvement in signal to noise
ratio and operating range.
Battery Options and Operating Time
Switching power supplies convert regulated battery
voltages to operate various circuit stages with maximum efficiency. With the variety of alkaline, lithium and
rechargeable NiMH batteries available today in the AA
format, there are many choices to maximize operating
time or minimize cost as needed for any application.
Frequency Blocks
Lectrosonics established a “block” numbering system
years ago to organize the range of frequencies available from the low 500 MHz band to the upper 700
MHz band. Each block includes 256 frequencies in 100
kHz increments. The block number is part of a simple
formula to derive the frequency. The block number is
multiplied by 25.6 to produce the lowest frequency in
the block. For example, block 27 x 25.6 = 691.200 MHz.
Circulator/Isolator
The RF output circuit includes a one way circulator/isolator
using a magnetically polarized ferrite. This device greatly
reduces the RF intermodulation produced when multiple
transmitters are used in close proximity to one another
(several feet apart). The isolator also provides additional
RF output stage protection.
Compatibility Modes
SMDa transmitters were designed to operate with
Lectrosonics Digital Hybrid receivers and will yield the
best performance when doing so. However, due to the
flexibility of digital signal processing, the transmitters
can also operate in various compatibility modes for use
with IFB.
Rio Rancho, NM
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SMDa Series
Controls and Functions
Modulation
LEDs
Battery
Compartment
Cover Plate
Battery
Compartment
Thumb Screw
PWR LED AUDIO Button
LCD Screen
The LCD is a numeric-type Liquid Crystal Display with
several screens that allow settings to be made with the
AUDIO, FREQ, UP and DOWN to configure the transmitter. Turn on and turn off countdowns appear in the
LCD allowing the transmitter to be turned on for adjustments without the output stage enabled, and to prevent
accidental turn off.
Power LED
The PWR LED glows green when the battery is good.
The color changes to red when there is about 30
minutes of operation left with the recommended lithium
battery. An alkaline battery will have about 20 minutes
of life left. When the LED begins to blink red, there are
only a few minutes of life.
A weak battery will sometimes cause the PWR LED to
glow green immediately after being put in the unit, but
will soon discharge to the point where the LED will go
red or shut off completely. When the SMDa is in SLEEP
mode, the LED blinks green every few seconds (See
Sleep Mode, page 8).
Note: A NiMH battery will give little or no warning
when it is depleted. If you wish to use NiMH
batteries in the transmitter, we recommend trying
fully charged batteries in the unit, noting the length
of time that the batteries will run the unit and then
using the battery timer feature available on most
Digital Hybrid receivers.
Audio Input Jack
The Servo Bias input on the SMDa Series transmitters
accommodates virtually every lavaliere, handheld or
shotgun microphone available, plus line level signals.
Battery Compartment and Thumb Screw
The large knurled thumbscrew is used to release or
secure the Battery Compartment Cover Plate, allowing
access to the battery.
LCD
UP Arrow
Audio
Input Jack
DOWN Arrow
FREQ Button
Modulation LEDs
The Modulation LEDs provide a visual indication of the
input audio signal level from the microphone. These two
bicolor LEDs can glow either red or green to indicate
modulation levels. 0 dB in the table below indicates full
modulation.
Signal Level -20 LED -10 LED
Less than -20 dB Off Off
-20 dB to -10 dB Green Off
-10 dB to +0 dB Green Green
+0 dB to +10 dB Red Green
Greater than +10 db Red Red
Audio Button
The AUDIO button is used to display the audio level
setting and low frequency roll-off. The UP and DOWN
arrows adjust the values.
The AUDIO button is also used with the FREQ button to
enter standby mode and to power the transmitter on or off.
Freq Button
The FREQ Button displays the selected operating
frequency and also toggles the LCD between displaying
the actual operating frequency in MHz and a two-digit
hexadecimal number that corresponds to the equivalent
Lectrosonics Frequency Switch Setting.
The FREQ button is also used with the AUDIO button to
enter standby mode and to power the transmitter on or off.
Up/Down Arrows
The Up and Down arrow buttons are used to select the
operating frequency, adjust the audio level, or set the
Compatibility Mode.
Pressing both arrows simultaneously enters the lock
countdown. Holding the two arrow buttons until the
countdown completes locks the control panel buttons so
they can only be used to display current settings. “Loc”
is displayed to indicate the controls are locked.
Once locked, the buttons can be unlocked only by removing the battery, or via the RM remote control (if this
function was enabled in the transmitter setup).
Antenna
The flexible antenna is built with woven, galvanized
steel mesh cable, cut to the 1/4 wavelength of the
center of the frequency block of the transmitter. The
antenna is extremely rugged and moisture resistant.
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LECTROSONICS, INC.
Super-Minature Belt Pack Transmitters
Setup with the LCD
Six screens are used to set up and operate the SM.
These screens are used to set the operating frequency,
adjust the audio input level, select the Compatibility
Mode or lock the control panel and power down the
transmitter.
Audio Screen
The Audio screen is used to
adjust input gain from 0 to +44
dB, and the low frequency rolloff from 35 to 150 Hz. Repeatedly pressing the AUDIO button
toggles back and forth between
the two displays. Press and hold the AUDIO button and
use the Up and Down arrows to make adjustments.
Frequency Screen
The Frequency Screen displays the operating frequency
in MHz or as a two-digit
hexadecimal number that corresponds to the equivalent
Lectrosonics Frequency Switch
Setting. Pressing the FREQ
button toggles between the two displays.
Compatibility Mode Screen
Holding down the Up arrow
button while powering up
the SMDa opens the
Compatibility Mode and
Power setting screens.
Note: RF transmission is
prevented while selecting
Compatibility Modes and Power level.
Use the Up and Down arrow buttons to select the desired compatibility mode:
• Hbr - for all Lectrosonics 400 Series Digital Hybrid
• IFb - for all Lectrosonics IFB receivers.
To power off from the compatibility mode screen, press
and hold AUDIO and FREQ together.
Wireless™ receivers, including the Venue. This mode
offers the best audio quality.
Turning the Power Off
With the unit turned on, simultaneously holding the AUDIO
and FREQ buttons starts a
countdown timer with numerals
on the right. The screen counts
down from three and the transmitter turns off when it reaches zero. Releasing either
button prior to the Power Off Timer screen indicating
zero returns the unit to normal operation and displays
the previous screen.
Initial Power Off
Timer Screen
Entering the Standby Mode
With the power turned off,
pressing the AUDIO and FREQ
buttons for about one second
places the unit in Standby
Mode. In this mode the RF output is turned off so all setup adjustments can be made
without interfering with other systems operating in the
same location. The screen displays “rf OFF” to remind
the user that the unit is not transmitting.
Holding the FREQ button in Standby Mode displays the
current operating frequency of the transmitter. The operating frequency can be changed by holding the FREQ
button and pressing either the Up or Down button.
Release the FREQ button, then press and hold it again
to toggle the display between frequency in MHz and the
hex code corresponding to the equivalent Lectrosonics
Frequency Switch Setting.
Holding the AUDIO button in Standby Mode displays
the current audio input level setting. This level can be
changed by holding the AUDIO button and pressing
either the Up or Down button.
Quickly pressing both the FREQ and AUDIO buttons
simultaneiously when the unit is in Standby Mode powers off the transmitter.
Standby Screen
Turning the Power On
With the power turned off,
simultaneously pressing and
holding the AUDIO and FREQ
buttons displays a timer with
numerals on the right.
The numerals count up from
one and the boot sequence begins when the count
reaches three. “LECtro” is displayed as the boot sequence begins. If either button is release prior to the
screen reaching numeral three, the unit will enter the
Standby Mode with no RF output.
Rio Rancho, NM
Initial Power On
Timer Screen
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SMDa Series
Lock/Unlock Screen
Simultaneously pressing and
holding both the Up and
Down arrow buttons during
normal operation starts the
Lock timer. The timer starts
at three and counts down to
zero. When the timer
reaches zero, the transmitter’s controls are locked.
The LCD will display the locked condition as long as the
arrow buttons are held, then revert back to the previous
screen when either button is released.
With the controls locked, the AUDIO and FREQ buttons
can still be used to display current settings. Any attempt
to change a setting by pressing either the Up or Down
arrow button will result in an on-screen “Loc” reminder
that the controls are locked. Remove the batteries to
unlock the control panel.
Important: Once the transmitter is locked, it
cannot be unlocked or powered off using the
buttons.The only ways to unlock a locked
transmitter are to remove the battery or unlock it
via the RM remote control.
Battery Installation
The SMDa is powered by two AA batteries. We recommend using lithium batteries for longest life or NiMH
rechargeable batteries for economy.
Note: Standard zinc-carbon batteries marked
“heavy-duty” or “long-lasting” are not adequate.
The battery status circuitry is designed for the voltage
drop over the life of lithium batteries.
To install new batteries:
1. Turn the Battery Cover Plate Thumbscrew counterclockwise, open the battery compartment and
remove any old batteries.
2. Insert the new battery (or batteries) into the housing. The positive (+) battery terminal goes into the
transmitter first.
3. Replace the Battery Cover Plate and tighten the
Battery Cover Plate Thumbscrew.
Kevlar covered vent
Remote Control Operation
SMDa Series transmitters may
be configured to respond to
signals from the RM remote
control unit or to ignore them.
This setting is accessed by
holding down the Down arrow
button while powering the
transmitter on. Use the arrow
keys to toggle between “rc on” (remote control on) and
“rc oFF” (remote control off). The default setting is “rc
on.”
If a remote control signal is detected but the transmitter
is set to “rc oFF”, the message “rc oFF” will be displayed briefly on the transmitter’s LCD, to confirm that a
valid signal was received, but that the transmitter is not
configured to respond to it.
Functions available from the remote control are:
• Audio Level
• Frequency
• Lock/Unlock Buttons
• Sleep/Wake (power saving mode)
In sleep mode, the SMDa uses 20% of the normal
amount of current. Sleep mode can only be invoked with
the remote control, and can only be revoked with the
remote control or by removing the battery. When in sleep
mode, the PWR LED blinks green every few seconds to
indicate that the SM is asleep and not turned off.
Remote Control Screens
Two battery
compartments
(SMDa)
Note: The RM is not included with SM Series
transmitters. “Dweedle tones” in .wav and mp3 files
can also be downloaded from the web site at:
http://www.lectrosonics.com/hybrid/rm/rm.htm
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LECTROSONICS, INC.
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