BHI NEDSP1062 KBD User manual

Page 1NEDSP1062-KBD Operating Manual
bhibhi
bhibhi
bhi
NEDSP1062 KBD
Amplified Noise Eliminating DSP Module
Installation and Operating Manual
Sound Engineering Solutions from bhi
1062-107D
Issue D

Page 2 NEDSP1062-KBD Operating Manual
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
impliedwarrantiesofmerchantabilityorfitnessfor
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.
Important Information

Page 3NEDSP1062-KBD Operating Manual
1. Introduction
1.1 NEDSP1062-KBD features 5
1.2 Limitations 5
1.3 Module connection and mounting 6
1.4 Keyboardmounting 7
1.5 Sounder mounting 8
1.6 DSP noise cancellation 9
2. Module description
2.1 Block diagram 10
2.2 Module layout 11
2.3 Pin functions 11
2.4 Controls 12
2.4.1 PCB controls 12
2.4.2Keyboard 12
2.5 Electrical characteristics 12
3. Installation
3.1 Installation overview 16
3.2 Module setup 17
3.2.1 Overview 17
3.2.2 Suggested set up procedure 17
3.2.3 Changes to output load 18
3.2.4 Other signal considerations 18
3.3 Driving the module from a low level signal 19
4. Functions
4.1 Keyboard 20
4.1.1 Power button 20
4.1.2 DSP level button 20
4.2 Set up 21
4.3 Demonstration modes 23
4.4 Noise cancellation levels 24
5. Application notes
5.1 Yaesu SP8 25
5.2 Kenwood SP31 28
5.3 bhi label 31
Contents

Page 4 NEDSP1062-KBD Operating Manual
6. Physical dimensions
6.1 Physical dimensions 32
6.2 Keyboard hole drilling detail 35
7. Troubleshooting
Troubleshooting 37
8. Other bhi products
Other bhi products 38

Page 5NEDSP1062-KBD Operating Manual
1. Introduction.
The NEDSP1061-KBD is a modular solution for noise
reduction.Itincorporates DigitalSignalProcessing(DSP)
technology to provide up to 35dB of noise cancellation
and 65dB of tone reduction. The module features an on
boardpoweramplifiertoallowittobeeasilyincorporated
in to existing equipment by installing the module in line
with the loudspeaker. All functions of the module are
controlled by an easy to use keyboard.
1.1 NEDSP1062-KBD module features:
Fully adaptive noise cancellation up to 35dB
Input and output level controls
Input level over load indication
Virtually no distortion to speech signal
Easy to install
4/8 levels of noise reduction (selectable)
Frequency response 50Hz - 4.3KHz
3 Watts output (4W)
Single button operation of DSP mode with LED and
audible indication
12 - 18V supply range
27dB on board gain
Power on/off - bypass pushbutton
Small size 37 x 50mm (DSP pcb)
Audio bypassed when power disconnected
Supplied with fixing and wiring kit and all labels
1.2 Limitations.
This module is designed to pass speech. Other signals
suchasdata,musicandmorse(CW)willtosomedegree
pass through, but the integrity of these signals
cannot be guaranteed.
1. Introduction.

Page 6 NEDSP1062-KBD Operating Manual
Figure 1. Mounting options
1.3 Module connection and mounting
The module is supplied with a pre-wired 2.1mm power
connector. The centre pin is positive. The audio in and
out are pre-wired pairs of wires, ready to be connected
intheaudio path.Theheatsink doublesupas amounting
bracket.
This module is designed to be driven from a high level
signal, capable of driving a load of 22W.
(The module can be easily modified to be driven from a
low power signal, see section 3.3 for more information).
The module can be mounted
using the supplied self adhesive
foam pad. Ensure that none of
the circuit pins can make contact
with any metallic parts.For improved heat dissipation
and a more rigid mechanical
fixing the heatsink can be
reversed and used as a bracket.
Note that the heatsink is at 0V
potentialandthereforemayhave
to be electrically insulated from any other metallic parts.
Alternativelythemodulehasfour
fixing holes which allow it to be
fixed to pillars.
(See section 6 for hole details
and physical dimensions).
1. Introduction.
Using the heatsink
as bracket
Self adhesive
pad
Mounting using
PCB pillars

Page 7NEDSP1062-KBD Operating Manual
1. Introduction.
If the installation has limited
space, and is housed in a metal
enclosure, the heatsink can be
removed, and the module
mounted directly on the chassis.
Thevoltageregulatorneedsto be
correctly insulated as the tab is
connected to 0V. Insulate both
the regulator and mounting
screw. For improved heat
dissipationuseasuitablethermal
pastebetween the powerdevices
and the mounting.
Figure 2.
Direct mounting.
Figure 3. Keyboard mounting 1.
The keyboard is
mountedthroughthe
enclosure to provide
an easy to use
interface. The
module is supplied
with a label to place
over the keyboard.
When the enclosure is thick enough the keyboard is
retained using a countersunk screw (supplied), which is
hidden by the label, see figure 3 above. Do not over
tighten the mounting screw.
keyboard
Front panel
label
Retaining
screw
Front
panel
Insulator
Insulator
Voltage
Regulator
1.4 Keyboard mounting.
(not supplied)
(not supplied)

Page 8 NEDSP1062-KBD Operating Manual
Figure 4.
Keyboard mounting 2.
If the enclosure is too
thin to incorporate a
countersunk screw
(such as fitting into
sheetmetal)thenitcan
be retained by a
instrument head
screw.
The label needs to be
cut out to allow the
screw to pass through
from the outside. This
can be easily achieved
byapplyingthelabel to
the panel, then carefully cutting around the screw hole,
with a sharp knife.Again do not over tighten the screw.
Nut &
washer
Front panel
label
keyboard
Retaining
screw
Front
panel
1.5 Sounder mounting.
Cutasmallpieceofthe
self adhesive foam
(supplied)to mount the
sounder.
Do not cover the small
hole in the face of the
sounder.
For best results mount
the sounder where it
can radiate sound to
the outside the case,
for example on an air
vent. Figure 5. Sounder mounting
Sounder
Backing paper
Backing
paper
Self adhesive
foam
Case
Keep this
hole clear
Cut hole
for screw
1. Introduction.

Page 9NEDSP1062-KBD Operating Manual
1.6 DSP Noise cancellation.
The bhi DSP processes the incoming signal and then
differentiates the speech from the noise. The unwanted
noise and interference is then attenuated to leave only
thespeech.Thefollowing diagramsaretakenfromactual
audio signals and illustrate how the signal is being
processed.
Figure 6. Noise cancellation.
Original signal.
Speech with a lot of
background noise
Processed speech.
Speech with reduced
noise
Speech Noise Reduced noise
1. Introduction.

Page 10 NEDSP1062-KBD Operating Manual
2. Module description.
Figure 7. NEDSP1062-KBD block diagram
1
3
8
Polarity
protection
Internal
pull up
resistors
Input level
set
In
9
overload
detect
Digital to analogue
conversion
Output level
set Pow er Amp
BCD
DSPlevel select
Xtal
Clock generator
DSP core
5V
5V
Regulator
Latch
12V
regulator
3.3V
regulator
3.3V 12V Relay
Drive
Relay 1
ON
14
Analogue to
Digital conversion
7
0V
10
12
6
Power supply
section
PCB
Connections
13
5
J3
Input
Load
resistor
Agnd
Agnd
Vin
NC
NO
NO
NC
DSP
3V3 0V
PCB
microcontroller 4
Keyboard
interface
8
N/C
N/C
Relay 1 Out
11
2.1 Block diagram.
2. Module description.

Page 11NEDSP1062-KBD Operating Manual
2.2 Module Layout.
The following diagram shows the layout of the
NEDSP1062-KBD module.
Pin No. Name Description Notes
4N/C Do not connect Not used
5Vin Supply voltage 12 - 18VDC power in
6N/C Do not connect Not used
70V 0V connection 0V power connections
9In Audio input Audio signal in to be processed
10 Out Audio output Procesed audio signal out
11 Agnd 0V for input audio signal Analogue ground for audio in
12 Agnd 0V for output audio signal Analogue ground for audio out
Table 1. NEDSP1062 connection functions
2. Module description.
Figure 8. NEDSP1062-KBD connections and controls
Input
level set
(P2)
Output
level set (P1)
Input overload
indicator LED
Mounting
holes
Audio
bypass
relay
Thefollowingtablegivesadescription ofthepinfunctions.
Note:
Wiring obmitted for clarity
Sounder
volume (P3)
2.3 Pin functions.

Page 12 NEDSP1062-KBD Operating Manual
2.4 Controls.
2.4.1PCB.
Thelevelcontrolsprovideadjustmentfor the audio levels
enteringandleavingthemodule.Themodulesare factory
set to the maximum level.
Turning the potentiometers clock wise will decrease the
levels. These potentiometers do not have end stops, so
it is possible to set them in a position where the audio
will be lost.
Audible indication of operation is provided by an piezo
sounder. The volume of this sounder can be varied by
potentiometer P3. The sounder volume is independent
of the incoming audio volume.
2.4.2Keyboard.
The keyboard controls all of the module functions
including power on/off.
2. Module description.
Figure 9. NEDSP1062-KBD keyboard.
Power button
(power and
Audio bypass)
DSP
level
button
Tri colour
LED
Mounting hole

Page 13NEDSP1062-KBD Operating Manual
2.5 Electrical characteristics.
Symbol Parameter Test Conditions Min. Typ. Max. Units
VsSupplyvoltage 12 16 18 V
IqsQuiescent current Vs= 12V
Vs= 16V
Vs = 18V
4.6
6.8
7.1 mA
Iqon Quiescent current DSP on
no load no signal
Vs= 12V
Vs= 16V
Vs= 18V
143
160
161 mA
ELECTRICAL CHARACTERISTICS
(Vs=16V, Tamb= 25ii
ii
iC unless otherwise stated)
DC CHARACTERISTICS
AC CHARACTERISTICS
Symbol Parameter Test Conditions Min. Typ. Max. Units
PoOutput power
d = 10%
f = 1KHz RL= 8W
RL= 4W
12V
1.16
1.7
16V 18V
2.06
3.17
Vs
W
W
ViInput sensitivty
4Wload
f = 1KHz PO= 0.5W
PO= 1.0W
PO= 2.0W
60
90
130
mV
ViInput sensitivty
8Wload
f = 1KHz PO= 0.5W
PO= 1.0W
PO= 2.0W
81
117
180
mV
BFrequency response
(-3dB) Po= 1W
RL= 8W50 4300 Hz
dDistortion f = 1KHz PO= 0.2 - 2.4W R L= 8W
PO= 0.2 - 2.4W R L= 4W0.8
0.8 %
RiInput resistance 21 22 23 W
GvVoltage gain f = 1KHz 27 dB
n Efficiency f = 1KHz PO= 3W R L= 4W
PO= 2W R L = 8W33
38 %
ANALOGUE CHARACTERISTICS
Symbol Parameter Test Conditions Min Typ Max. Units
TdSystem delay 26 mS
2. Module description.
Table 2. Electrical characteristics 1

Page 14 NEDSP1062-KBD Operating Manual
-20
-15
-10
-5
0
5
0 1000 2000 3000 4000 5000 6000
Figure 10.Frequency response
Frequency(Hz)
Output (dB)
0
2
4
6
8
10
12
00.511.522.533.5
Figure 11. Distortion vs. Output power
Distortion
Output power (W)
VS= 16V
f = 1KHz RL = 8W
RL = 4W
2. Module description.
RL= 8W
VS= 16V
P = 1W
-3dB

Page 15NEDSP1062-KBD Operating Manual
Figure 12. Sensitivity.
0
0.5
1
1.5
2
2.5
0 50 100 150 200
Input voltage (mV)
Output power (W)
RL= 8W
RL= 4W
VS= 16V
f = 1KHz
2. Module description.

Page 16 NEDSP1062-KBD Operating Manual
Figure 13. Basic connection diagram
3.1 Installation overview.
The NEDSP1062-KBD module is inserted into the path
of noisy audio. The input and output level controls allow
the module to be fine tuned to suit most applications.
3. Installation
Audio in
Power amp
+
-
Break Circuit
here
Audio Out
(Loudspeaker)
The input to the module is loaded at 22Wto provide a
dummyloadtotheprecedingcircuit. Thiscanberemoved
if required, such as using the module in applications
where the audio source is provided by a low level, low
power signal source. More information on this can be
found in section 3.3 in this operating manual.
If Vin is less than approx. 13.8V ensure the power supply
is well decoupled otherwise the power supply rejection
ratio will deteriorate. Best results are obtained in the
range of 13.8V - 16Vdc.
Audio in
NEDSP1062Power amp
+
-
IN
Agnd Agnd
OUT
Keyboard
Power
10
12
9
11
Black
Piezo
sounder
Blue
Red
Black
3. Installation.

Page 17NEDSP1062-KBD Operating Manual
3.2 Module setup.
3. Installation.
3.2.2 Suggested set up procedure:
Basic setup procedure.
Connect input source and output device.
Ensure the NEDSP1062-KBD is switched off.
Set the audio source to a typical audio level.
Switch on the NEDSP1062-KBD.
Adjust the input control (P2) until the overload LED
illuminates. Reduce the level by approx. 1/4 turn.
Adjust the output level to the desired level.
Hold down the DSP button and adjust the volume
of the sounder to suit using P3.
Toobtainthebestresultsfromthenoisereductionthe
moduleshouldbesetuptogiveoptimumperformance.
Theinputsensitivitycontrolhasarangeof0.70mW-
3Wtoprovide2W (W)output.
Undercertainconditions,RFbreakthrough can
sometimesoccur.Tominimizethis,the input level (P2)
may need to be reduced or go to the FAQ page on the
bhiwebsiteanddownloadtheFAQonRFbreakthrough.
Undercertainconditions the DSP can create asmall
amountofnoise, normallywhentheunithas nosignal
applied.Youshouldnotbeabletohearthisnoisewhen
a signal is applied.
Both the input and output levels are adjustable on the
module.Thisallowseasyintegrationintothetargetsystem.
3.2.1Overview.

Page 18 NEDSP1062-KBD Operating Manual
The NEDSP1062-KBD requires a signal of 125mV rms
or greater for optimum performance. Signals lower than
thismaybeusedbutthe noise cancellation performance
will decrease, as the signal levels drops. If the unit is
used with low level signals such as microphones, the
signal will need amplifying before applying it to the
NEDSP1062-KBD.
Due to the adaptive nature of the noise cancellation a
small delay may be heard when the audio signal
changes. For optimum performance provide the module
with a constant signal where possible.
When switching on the unit a thump may be heard in the
loudspeaker.
3. Installation.
Figure 14. Input circuit -
module powered down
22 W
OUT
12
Agnd
Agnd
9
10
V
Audio
Input
NEDSP1062
R6
IN
Load
11
The audio input to the
module is loaded at
22W. This load is
effectively connected
across the output load
when the unit is
switched off
(bypassed).
This will reduce the
impedance presented
to the audio source.
For example:
8W will reduce to 5.9W
4Wwill reduce to 3.4W
3.2.3Change to output load.
3.2.4Other signal considerations.

Page 19NEDSP1062-KBD Operating Manual
Figure16.Circuitmodificationforlowpowersignaldrive.
3.3 Driving from a low signal source.
The input to the module has a low impedance.This is to
provide correct loading to any power circuits driving it. If
the module needs to be driven from a low power signal
then it must be modified in the following manner.
Cut the
leg on this
resistor
3. Installation.
22
W
OUT
12
Agnd
Agnd
9
10
Load V
Audio
Input
NEDSP1062
R6
IN
11
Circuit
modification
Figure 15. Physical modification for low power signal
drive.
Note:
Wiring
omitted for
clarity.

Page 20 NEDSP1062-KBD Operating Manual
4. Operation.
4. Operation.
4.1 Keyboard.
The keyboard has 2 buttons and a tricolour LED.
4.1.1Power button.
Thepowerbuttonswitchedthe module on and off. When
the module is off, the audio bypasses the module, so
the circuit will behave as if the module isn’t present.
Switching the power on routes the audio through the
module.
Note: If the power is on and the DSP is switched off, the
audiostillpassesthrough theDSP-butwithoutanysignal
processing.
A single press on the button switches on, and a single
press will switch off. Also with the power connected and
the module switched off the circuit will still draw 6mA.
4.1.2DSP level button.
This button is used to set the following:
•DSP on/off
•DSP level
•4 or 8 levels of noise cancellation
•Demonstration modes
Figure 17. NEDSP1062-KBD keyboard.
Power button
(power and
Audio bypass)
DSP
level
button
Tri colour
LED