West Mountain Radio CLRdsp 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.
CLRdsp ClearSpeech®
Noise Reduction Digital
Signal Processor

2
West Mountain Radio Operating Manual
Thank you for choosing the CLRdsp ClearSpeech®Noise Reduction Digital
Signal Processor. The noise reduction circuit and audio amplier in CLRdsp
is extremely e󰀨ective in improving communication clarity. Mobile and base
operation is less fatiguing and much more fun!
CLRdsp 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, lightening 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.
CLRdsp may be mounted in any convenient location, such as under a station
speaker. It ts perfectly under the West Mountain Radio COMspkr. Included
are two (2) 6ft. cables with 1/8-inch stereo audio connectors for audio input and
external speaker output. Volume, tone and DSP ltering levels may be adjusted
by use of the front panel controls. A headphone connector on the front may
be used with any mono or stereo headphone set. The unit also includes a 6ft.
power cable with Powerpole® connectors that will plug into a 13.8 volt supply.
Choosing a Mounting Location
The CLRdsp should be placed nearby for easy operation and close to the radio,
speaker, and power supply. The 6ft. cables can be lengthened with extensions.
This unit is not weather resistant and suggested to use in a dry place out of
direct sunlight.
Connections
Rear Panel
SPKR LEVEL IN: 1/8” jack that accepts audio from a low-impedance external
speaker jack or headphone output jack typically found on Amateur transceivers.
Use one of the supplied stereo patch cables to connect to the radio. If a radio
has a stereo output, the CLRdsp will only receive the left audio channel (tip).
A stereo cable is supplied because they are always safe to use even in mono
jacks. The audio input is transformer coupled within the CLRdsp to reduce the
chance of ground loops.
LINE IN: 1/8” jack that accepts audio from a low-level source, typically found on
the headphone jack of portable Shortwave receivers. If using such a radio, use
this jack instead of the SPKR LEVEL IN jack.
LINE OUT: 1/8” jack provides a line-level ltered audio output suitable for
recording. It can be connected to the LINE-IN (or MIC-IN) jack on a computer
using a stereo patch cable for digital recording using suitable software. Only the
left audio channel (tip) is passed.

3
West Mountain Radio Operating Manual
SPKR OUT: This 1/8” jack connects to a low-impedance external speaker. The
CLRdsp uses a bridge amp type output which means it is important that your
external speaker is not grounded. The tip is positive and the sleeve is negative.
Use one of the 6ft. stereo cables provided to connect to the external speaker.
Recommended for a 4 or 8-ohm external speaker. Do not use a powered
external speaker with this jack as these typically have grounded sleeves.
Power Jack: The CLRdsp comes with a 6ft. power cable. One end is a 2.1 mm
power plug (tip hot) 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 VDC
and the other wire to ground. The CLRdsp is protected from a reverse polarity
power connection. A small 1-amp 12 or 15-volt, wall mount power supply (wall
wart) may be used to power the CLRdsp. The plug required is 5mm OD with a
2.1 mm pin, and the pin is positive. West Mountain Radio carries an appropriate
supply for 117 VAC.
Front Panel
Headphone Jack: The front panel headphone jack can work with mono or
stereo headphones. A jumper (J8) is provided on the main circuit board to
select which type of headphones will be used with the CLRdsp. Remove the
case screws carefully and locate jumper J8.
Jumper J8 ON: Stereo headphones (audio fed to both tip and ring)
Jumper J8 OFF: Mono headphones (audio on the tip only)
Warning: Do not connect shield contact on HDPH or Spkr Out to DC ground.
The high level audio works ne with modern 8 to 600 ohm headphones.
Plugging in headphones will mute the external speaker.
Important: The headphone jack should only be used with headphones. Do
not make a connection here that would cause the sleeve to be grounded, for
example a connection to external equipment.
Controls
Volume Control: The desired volume level from the external speaker may be
controlled with the volume knob on the front of the CLRdsp unit. Headphone
volume will also be a󰀨ected. Adjust the radio’s volume control and this control
to achieve the desired audio output.
Tone Control: Adjust the tone control for desired level of bass/treble response.
Filter Control: Adjusts the amount of active DSP ltering.

4
West Mountain Radio Operating Manual
Operating
CLRdsp is easy to operate. When power is supplied to the CLRdsp, the CLIP LED
will turn green to indicate the unit is on.
The front panel “Filtering’ control allows continuous DSP level adjustment. When
turned fully counterclockwise, the DSP is bypassed. When turned fully clockwise,
maximum DSP ltering is realized. Maximum ltering is rarely needed during use.
A recommended setting is at the 10 - 12 o’clock position for typical HF channel
conditions. If the unit is powered up and the ltering knob is fully clockwise, the
rmware version is reported in Morse Code.
If the incoming audio level is too high the CLIP LED will ash. Reduce the input
just below ashing. Clipping disrupts the noise reduction circuit.
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 patented algorithms. Take notice of the
DSP battling 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 varying siren, it is
greatly reduced as well, but not as much as a 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.
Power Amplier
CLRdsp contains a power amplier integrated circuit. It produces 7.5 watts RMS
maximum into an 8 ohm loudspeaker, when connected to a 13.8 volt DC source.
The voltage gain is 46 dB typically. The amplier has protection from a shorted
speaker.

5
West Mountain Radio Operating Manual
Specications
Enclosure Aluminum, powder coat painted
Dimensions 5.75 x 4.25 x 1.25 inches
Power Requirements 9 to 16 Vdc; 1.1A typical before onset
of clipping
Audio Input High impedance, 0.01 VAC
Voltage Gain 46 dB
Audio Output Power 11 watts RMS into 4 ohms @ 13.8 VDC
Maximum Audio Output Voltage 7.75 Vrms
Input Clipping Level 0.04 volts RMS
Noise Reduction Characteristics Adaptive, single tone greater than 50 dB
Powerpole® is a registered trademark of Anderson Power Products
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
CLRdsp 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.
Speaker level input is via a coupling transformer. The speaker level input ground
is not connected to the power return. This helps reduce any ground loops.

CLRdsp Warranty
CLRdsp 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 CLRdsp 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 CLRdsp 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
tel [phone] fax [phone]
FCC INFORMATION
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 again harmful interference in
a residential installation. This 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 o󰀨
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 di󰀨erent from that to
which the receiver is connected
• Consult the dealer or an experienced radio/TV technician for help
Modications not expressly approved by the manufacturer could void the
user’s authority to operated equipment under the FCC Rules.