BHI DESKTOP User manual

bhi DESKTOP
Amplified DSP noise cancelling base station speaker
User Manual
bhi Ltd
DSP noise cancellation products for radio and voice communications
2067 Manual iss C

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Important Information:
Copyright
This publication, including all photographs and illustrations is protected under international
copyright laws, with all rights reserved. Neither this manual, nor any of the material within,
may be copied or reproduced without the written consent of bhi Ltd.
Disclaimer
The information in this document is subject to change without notice. bhi Ltd makes no
representations or warranties with respect to the contents hereof and specifically disclaims
any implied warranties of merchantability or fitness for any particular purpose.
Furthermore, bhi Ltd reserves the right to revise this publication and to make changes from
time to time in the content hereof without obligation of bhi Ltd to notify any person of such
revision or changes.
Table of Contents
1. Packing list ……………………………………………………………………..page 2
2. Introduction……………………………………………………………………..page 3
3. DSP noise cancellation………………………………………………………...page 3
4. Installation……………………………………………………………………….page 4
5. Speaker operation……………………………………………………….………page 5
6. Speaker tone volume adjustment…..….……..………………………..…..…page 5
7. Sleep mode………………………………………………………………………page 5
8. Input overload…………………………………………………..………………..page 5
9. Specification.……..………………………………………………………….......page 5
10. Accessories………………………………………………………………….…Page 6
11. Troubleshooting/FAQ’s…...…………………………………………………....page 6
12. bhi support……………………………………………………………………...page 6
1. Packing List
The bhi DESKTOP is shipped with the following items:
 DESKTOP DSP noise cancelling speaker
 3.5mm mono plug audio lead terminated with 4mm banana plugs
 Speaker mounting bracket
 Fused DC power lead (1030-FPL with 2.1mm power plug centre +ve)
 User manual
 Customer feedback card

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2. Introduction
The bhi DESKTOP speaker is a microprocessor controlled amplified DSP noise cancelling
base station speaker that removes noise and interference to improve the quality of speech
in noisy radio and voice communications. It is suitable for use in base station applications
where background noise and interference mean that you cannot clearly hear what is being
said. The speaker will enable the user to listen and concentrate “stress-free”. Suitable
applications where the speaker will be of great benefit are: amateur radio, two-way radios,
HF radios, marine communications, scanners, taxi base stations etc. The DESKTOP
speaker incorporates unique Digital Signal Processing technology (DSP) to remove the
unwanted background noise and interference. The DESKTOP speaker has separate line
level and speaker level inputs allowing it to be used with a wide range of radio and audio
equipment including SDR radios. There is also a 3.5mm headphone socket on the side of
the speaker and either mono or stereo headphones can be used.
The DESKTOP speaker comprises a 4” bass driver and a 1” tweeter unit, with an amplified
bhi DSP noise cancelling unit capable of producing up to 10Watts audio (peak). The
speaker requires an audio input signal of between 160mV and 1.6mV peak-to-peak for line
level, and 350mV and 3.5V peak-to-peak for speaker level input, and requires a DC power
supply of between 12 and 18 Volts (2.5A peak). The unit is supplied with a quality
moulded 3.5mm mono jack plug lead terminated with 4mm banana plugs, a 2.1mm fused
DC power lead and a user manual. Accessories are available see section 10.
Note: The speaker is mainly designed for speech signals and is not really suitable for
music.
3. bhi DSP Noise Cancellation
The bhi DSP processes the incoming signal and differentiates the speech from the noise.
The unwanted noise and interference is then attenuated to leave only the speech. The
following diagrams are taken from actual audio signals and illustrate how the signal is
processed.
Original signal.
Speech with a lot of background noise
Processed speech.
Speech with reduced noise

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4. Installation
The speaker is supplied with a mounting bracket that can be left on in case of permanent
fixing, or removed altogether depending on personal choice.
Connections to your radio equipment can be made via audio sockets on the rear of the
speaker, using either the speaker level terminals (audio lead supplied), or the 3.5mm
stereo line level socket (audio lead not supplied).
Set the volume on your radio or audio source to the normal listening level prior to using the
DESKTOP speaker.
Connect the audio lead to your radio, and then connect the other end to the relevant input
connection on the rear of the DESKTOP speaker.
Connect the 1030-FPL fused DC power lead supplied to a power supply capable of
providing 12 - 18VDC @ 2A (2.5A peak), or connect a suitable DC power supply. The
centre pin of the 2.1mm power connector is positive, and the red lead or the black lead
with the white stripe is positive.
DESKTOP controls:
Volume control
Filter level select
Headphone socket
Line level input socket
2.1mm power socket
(centre +ve)
4mm speaker level input terminals

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5. Speaker Operation
Once installed and connected, switch the power on. The LED behind the grille will
illuminate either green or red, and a rising audio tone will be heard. You should hear audio
through the speaker now. Turning the “Volume” control clockwise or anticlockwise will
increase or decrease the volume level, at the same time you will hear a low frequency
audio sound through the speaker when the volume control is turned. The volume of this
audio “blip“ sound will vary as you rotate the volume level control knob. Subsequent
presses of the “Volume” control knob will turn the speaker on and off. When switching
back on the speaker will go to the last stored setting when switched off.
Pressing the filter level control knob switches the DSP noise cancelling filter on and off, a
red LED indicates filter off, and a green LED filter on. The filter level is simply changed by
turning the filter level control knob clockwise or anticlockwise. There are 8 filter levels
indicated by 8 different frequency tones. The lowest tone indicates the lowest filter level
and the highest tone indicates the maximum filter level. You can easily adjust the filter
level to suit your current operating conditions.
Note: If the power is on and the DSP is switched off (red LED), the audio passes through
the DSP filter, but without any signal processing.
6. Speaker Tone Level Volume Adjustment
There are four volume level settings for the audible speaker tones; off, low, medium and
high. To change the tone volume level to your preferred setting, press and hold the
volume control until you hear an audible tone and the LED flashes continuously. Release
the volume control to select the current level, otherwise press and hold the volume knob
again until you hear the next tone. (Note that with the audio tone in position off, only the
LED will flash when the volume control is pressed).
7. Sleep Mode
The DESKTOP speaker has a built in sleep mode feature whereby it will be put into
standby mode when there is no signal present after approx 60 minutes. This is indicated
by falling tones. In this mode the speaker only draws a small amount of current (approx
10mA). The speaker will be woken up if a signal is received whilst in sleep mode. This is
indicated by rising tones. If the speaker is switched off manually by pressing the volume
control knob momentarily with power still applied, the sleep mode is inactive and to wake
the speaker up in this instance, press the volume control knob again and the speaker will
switch on, with the last known settings restored.
The sleep mode function can be turned off and on by pressing and holding the filter level
control knob for approx 4 seconds. Falling tones indicate that the sleep mode is enabled,
and rising tones indicate that the sleep mode is disabled.
8. Input Overload
The DESKTOP has audio input overload protection for both the line level and speaker
level inputs. If the signal peaks go over the limits set out in the specification, the LED will
change red and flash 3 times. If the audio level is constantly above the overload

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threshold, the red LED will flash continuously. Reducing the audio input level will bring the
speaker back in to normal operation.
9. Specification
DC Power
Connector type 2.1mm DC power jack (centre positive)
Input voltage 12 to 18 Volts DC
Input current 10mA standby (typical)
125mA active (no signal)
2.5A peak
Line Level Audio Input
Connector type 3.5mm Mono or Stereo line level
Input voltage range 160mV to 1.6mV pk-pk
Input impedance 10kΩ (±2kΩ) nominal
Speaker Level Audio Input
Connector type 2 x 4mm socket/screw binding posts (mono)
Input voltage range 350mV to 3.5V pk-pk
Input impedance 8Ω (±2Ω) nominal
Input power rating 1.5W max
Audio Output
Speaker Output power 10W peak (supply voltage of 18V)
Bandwidth 50Hz to 4.3kHz
Volume levels 16 levels (3dB steps)
Headphone output 3.5mm mono or stereo (8 to 64 Ohms)
DSP Noise Cancellation
Levels 8 levels + off
Noise reduction 9dB to 35dB
Tone reduction 4dB to 65dB
Indications
Status LED Multicolour LED (red, amber, green).
Audio tones Power-up, power-down, DSP level, volume and memory store.
Controls
Power/Volume Digital rotary encoder with push function
DSP level Digital rotary encoder with push function
Physical
Weight (packed) 1.90kg
Dimensions 200(H) x 150(D) x 160(W) mm

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10. Accessories:
PSU12-2A - 12V 2A DC UK mains plug-in power supply, with centre +ve
2.1mm DC output connector. This power supply is high quality and very
reliable. It has built in Short, over voltage & over current and over
temperature protection.
Order code ALD-007 3.5mm stereo plug to 3.5mm stereo plug lead 1.2m
long, for use with line level input.
Order code ALD-008 3.5mm stereo plug to 3.5mm stereo plug lead 3m long, for use with
line level input.
Order code: DESKTOP_FEET - Set of 3 Rubber feet for
the DESKTOP speaker (2 x 16mm and 1 x 6mm). 16mm feet fit
next to the front plastic feet and the 6mm fits onto the metal
bracket.
Order code: A-DESKTOP_ACBL – Replacement audio lead
3.5mm mono plug to 2 x 4mm banana plug 1.2 M long.
Order code: ALD-009 - 3.5mm stereo plug to 3.5mm mono socket (Elecraft stereo to
mono audio lead, tip only connected).
11. Troubleshooting/FAQs
Speaker doesn’t work at all, no sound from the speaker:
 Check that the power connector on your power supply is suitable for the power
socket on the speaker (2.1mm, centre positive).
 Check that you have switched your radio communication equipment on and that you
have a signal for the speaker to process. To verify this, remove the audio connector
from the external speaker socket on your equipment.
 Check that the DESKTOP Power LED is on.
The speaker works but the noise cancellation doesn’t appear to improve the audio
quality of the signal:
 Check that the filter is switched on (green or orange LED).
 Increase the filter level to see if this makes a difference.
 Increase the volume on the audio source.
4. Troubleshooting/FAQs
The volume from the speaker is low and cannot be increased:
 The speaker is designed to work with the external speaker sockets of radio
communications equipment, and although it will work with some earphone and
headphone sockets, there may be occasions where the signal output from these
types of output sockets is not enough for the speaker electronics to process the
signal effectively. Try using the line level input socket using a 3.5mm stereo plug to
plug lead.
Sometimes there is a short delay before the noise cancellation is active:
 This is due to the time the DSP takes to start processing the signals. This gives you
the opportunity to check that the DSP is not taking out any detail from the signal.
Sometimes I can hear a processing sound in the speakers when no signal is
present:

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 This is caused by the DSP processor and is normal. When a signal is applied you
should not be able to hear this in the speaker.
12. bhi Support
Every Desk Top “Noise Away” noise eliminating speaker comes with a 12 month
guarantee against defective materials and workmanship. If you do have a problem then
please refer to the troubleshooting guide (section 11). If you have not resolved your
problem then please contact us. Before you make your call please have the following
information to hand:
1. Your serial number (found on the back of the unit).
2. Details of when and where you purchased the unit
See our website for FAQs for answers to other common questions, otherwise most queries
can be resolved over the telephone. If not we will arrange with you to have your unit sent
back to us for analysis, repair or replacement (if within 12 months from date of purchase, if
outside the guarantee period an estimate of the cost of repair will be given). For contact
details please refer to the back cover of this manual. If you have any suggestions for
improvements please complete and return the customer feedback form.
Weee Statement for correct disposal of this product:
(Applicable in the European Union and other European countries with separate
collection systems).
This marking shown on the product or its literature, indicates that it should not be
disposed of with other household wastes at the end of its working life. To prevent possible
harm to the environment or human health from uncontrolled waste disposal, please
separate this from other types of wastes and recycle it responsibly to promote the
sustainable reuse of material resources.
Household users should contact either the retailer where they purchased this product, or
their local government office, for details of where and how they can take this item for
environmentally safe recycling. Business users should contact their supplier and check
the terms and conditions of the purchase contract. This product should not be mixed with
other commercial wastes for disposal.
bhi Ltd
PO Box 318
Burgess Hill
West Sussex
RH15 9NR
England
Telephone: + 44 (0)1444 870333
Email: [email protected]
Web: www.bhi-ltd.com