West Mountain Radio CLRstereo ClearSpeech User manual

www.westmountainradio.com
1020 Spring City Drive
Waukesha, WI 53186
262-522-6503
[email protected]
©2019 West Mountain Radio, All rights reserved. All trademarks are
the property of their respective owners.
CLRstereo ClearSpeech®
Dual Noise Reduction Digital
Signal Processor

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West Mountain Radio Operating Manual
Thank you for choosing the CLRstereo ClearSpeech®Dual
Noise Reduction Digital Signal Processor. The noise reduction
circuit and audio amplier in CLRstereo is extremely e󰀨ective in
improving communication clarity. Mobile and base operation is
less fatiguing and much more fun!
CLRstereo noise reduction is superb due to the Digital Signal
Processor (DSP) passing voice and CW sounds, while attenuating
noise, such as atmospheric noise, hum, hiss, whistles, and static.
It e󰀨ectively removes heterodynes, ignition noise, lightning
crashes, power line noise. The process is dynamic and changes
with the interference and the signal, but the e󰀨ect is rewarding.
QSO’s are more fun without all the background noise. The DSP
recognizes the intermittent nature of CW and allows it to pass
noise free.
The CLRstereo uses the same Clearspeech®algorithm as the
CLRdsp product. The CLRstereo can process two channels
at once for use with two radios or a radio that can receive two
frequencies at once, Be aware that the CLRstereo does not
contain a power amplier like the CLRdsp. The output is su󰀩cient
for a headphone or low level speaker. For additional audio level
use an amplied speaker such as the COMspkr or PWRspkr.
The CLRstereo package includes these cables:
• (1) 6-ft. power cable with Powerpole®connectors
• (1) 1/8” Audio Cable, 6 ft.
• (1) 6-ft. audio cable with 3.5mm & stripped end
Choosing a Mounting Location
The CLRstereo should be placed nearby for easy operation and
close to the radio, speaker, and power supply. The 6ft. cable can
be lengthened with extensions.
This unit is not weather resistant and is suggested to use in a dry
place out of direct sunlight.
Powerpole®is a registered trademark of Anderson Power Products

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West Mountain Radio Operating Manual
Connections
AUDIO IN: 1/8” stereo jack that accepts audio from a low-
impedance external speaker jack or headphone output jack
typically found on Amateur transceivers. Use the supplied stereo
patch cable to connect to the radio if the radio has a stereo
output. If using two radios, use a right/left splitter adapter or
audio splitter cable to connect to two radios/audio sources.
PTT: 1/8” mono jack that can be used to indicate when the radio
is in transmit mode (active low). The CLRstereo uses the audio
level drop to detect transmit. In a noisy environment where the
audio level never drops completely out this can be used as a
denitive indicator. If the CLRstereo does not properly detect
transmit mode, when the transmit is complete, the CLRstereo
may take an additional second to learn the receive noise before
suppressing it.
AUDIO OUT: 1/8” stereo jack that contains both audio signals.
It can drive a stereo headphone, amplied stereo speaker set or
two small speakers.
Coaxial Power Jack: This is one of two possible sources of
power for the CLRstereo. The CLRstereo comes with a 6ft. power
cable. One end is a 2.1 mm power plug (center positive) and
the other is a pair of Powerpole®connectors. RED is for PLUS
13.8 VDC and BLACK is for Ground. If using other connectors,
just remove the Powerpole®and connect the white striped wire
to PLUS 13.8 VDCand the other wire to ground. The CLRstereo
is protected from a reverse polarity power connection. A small
500mA, 12-volt, wall mount power supply (wall wart)may be used
to power the CLRstereo. The plug required is 5.5mm OD with a
2.1 mm pin, and the pin is positive. West Mountain Radio carries

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West Mountain Radio Operating Manual
an appropriate supply for 117 VAC. The CLRstereo will operate
correctly with any voltage from 9VDC to 15VDC. A quiet source
will reduce noise in the audio.
USB Power: This is one of two possible sources of power for
the CLRstereo. The USB jack may be connected to a PC or
standard USB charger to power the CLRstereo.
USB Data: This is the same connector as “USB Power.” When
connected to a PC two COM ports will appear at the PC. If they do
not appear (usually due to an older version of Windows) you will
need to install the WMR drivers. The USB drivers can be installed
byusingtheWMRDeviceDiagnosticUtility.Thisutilitycanbefound
on the West Mountain Radio website under Support > Downloads
(www.westmountainradio.com/content.php?page=wmr-downloads)
The CLRstereo has two CLRmodule units inside. The two COM
ports can be used to monitor and control the two units. This is not
required for normal operation. One use would be to update the
rmware. The CLRmod PC Utility program can be downloaded
from the aforementioned download page to monitor and control
the CLRmodule. A hardware interface must be provided to
interface the 0-3.3V signals on
the CLRmodule to the PC RS232
port or a USB port.
The West Mountain Radio
CLRstereo has two CLRmodules
inside and it has a USB interface
connected to those modules.
This provides an easy-to-use
development platform for the
CLRmodule.

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West Mountain Radio Operating Manual
Controls
Power: Simple On/O󰀨.
Power LED: Green on indicates the unit is powered.
Channel controls: For the right and left channels the following
are on the front panel:
• Volume Control: The desired volume level from the radio
may be controlled with the volume knob.
• Tone Control: Adjust the tone control for desired level of
bass/treble response.
• Filter Control: Adjusts the amount of active DSP ltering.
Clockwise increases ltering. A recommended setting
is at the 10 - 12 o’clock position for typical HF channel
conditions. When fully counter-clockwise no ltering is done
and music may be listened to.
• Clip LED: Red on indicates the incoming audio level is
too high. Reduce the input just below ashing. Clipping
disrupts the noise reduction circuit.
Center switches: The left switch controls the left output channel.
The right switch controls the right output channel. When a
switch is up, that output channel is connected to the left audio.
When a switch is down, the right audio is selected.
Noise Reduction Performance
The noise reduction is dynamic and adaptive. It senses the
random character of the voice or CW and permits it to pass
through. The repetitive nature of the noise is sensed and reduced
according to the specialized algorithms. Note the DSP battling

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West Mountain Radio Operating Manual
the di󰀨erence between the voice and the noise when both are
at equal level and the noise is constantly varying.
When the signal is CW, its intermittent character is sensed and
the CW is passed through. The noise is attenuated. When
the noise is steady, such as a heterodyne from a 40 meter
broadcast station (carrier whistle), it is attenuated greatly to
over 50 dB or about 0.003 times the original value. If the
noise is a moving heterodyne, it is greatly reduced as well, but
not as much as a xed heterodyne.
Transient sounds are greatly reduced, especially if they are
repetitious. The net e󰀨ect of the Digital Signal Processor is to
reduce atmospheric noise, static, hiss, ignition noise, power
line noise, carriers, hum, and heterodynes, while passing
voice and CW signals.
The adaptive nature of the noise reduction is apparent by
observing its convergent time. A single audible tone will
vanish in about 1 second. White noise diminishes in 1 to 2
seconds. Typical car noise and emergency alarms take about
2 seconds to reduce.
ClearSpeech Adaptive Speech Filter
The ClearSpeech Adaptive Speech Filter is an algorithm
designed to lter noise from audio signals containing both
speech and noise. It is implemented in a circuit board
containing DSP circuitry and a small audio power amplier.
Immunity from RF Interference
CLRstereo contains circuitry to reduce interference
from the transmitted radio signal. There are lters on
all input wires and decoupling capacitors at key points
throughout the electronics. There is a ferrite inductor in
series with the positive power lead. Audio level inputs
are via a coupling transformer. This helps reduce any
ground loops.

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West Mountain Radio Operating Manual
Specications
Enclosure Metal, powder coat painted
Dimensions 7.25” x 3.5” x 1.5”
Power Requirements USB power or 9 to 15VDC,
212mA typical
Maximum Audio Output 2Vpp into a high impedance load,
560mVpp into 8 Ohms
Input Clipping Level 585mVpp (volume control full
clockwise)
Noise Reduction
Characteristics
Adaptive, single tone greater than
50 dB

CLRstereo Warranty
CLRstereo is warranted against failure due to defects in workmanship or
materials for one year after the date of purchase from West Mountain Radio.
Warranty does not cover damage caused by abuse, accident, misuse, improper
or abnormal usage, failure to follow instructions, improper installation, alteration,
lightning, or other incidence of excessive voltage or current. If failure occurs within
this period, return the CLRstereo or accessory to West Mountain Radio at your
shipping expense. The device or accessory will be repaired or replaced, at our
option, without charge, and returned to you at our shipping expense. Repaired or
replaced items are warranted for the remainder of the original warranty period.
You will be charged for repair or replacement of the CLRstereo or accessory
made after the expiration of the warranty period.
West Mountain Radio shall have no liability or responsibility to customer or
any other person or entity with respect to any liability, loss, or damage caused
directly or indirectly by use or performance of the products or arising out of any
breach of this warranty, including, but not limited to, any damages resulting from
inconvenience, loss of time, data, property, revenue, or profit, or any indirect, special
incidental, or consequential damages, even if West Mountain Radio has been advised
of such damages.
Except as provided herein, West Mountain Radio makes no express warranties
and any implied warranties, including fitness for a particular purpose, are limited
in duration to the stated duration provided herein.
www.westmountainradio.com
1020 Spring City Drive, Waukesha, WI 53186
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