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tel: +44 (0)845 217 9926 fax: +44 (0)845 217 9936 bhi bhi bhi bhi bhi Installation and Operating Manual [email protected] www.bhi-ltd.co.uk Amplified Noise Eliminating DSP Module 1062-107D Issue E NEDSP1062-KBD Operating Manual NEDSP1062-KBD Operating Manual Page 40 Page 1 DSP Noise Cancellation
Citation preview
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating Manual Page 1
bhibhibhibhibhiNEDSP1062 KBD
Amplified Noise Eliminating DSP Module
Installation and Operating Manual
Sou
nd E
ngin
eerin
g S
olut
ions
fro
m b
hi
1062-107DIssue E
Page 40
bhi Ltd22 Woolven Close
Burgess HillWest Sussex
RH15 9RR
tel: +44 (0)845 217 9926fax: +44 (0)845 217 9936
bhibhibhibhibhiS
ou
nd
En
gin
eeri
ng
So
luti
on
s
DSP Noise Cancellation
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating ManualPage 2
Copyright
This publication, including all photographs andillustrations is protected under internationalcopyright laws, with all rights reserved. Neitherthis manual, nor any of the material within, maybe copied or reproduced without the writtenconsent of bhi Ltd.
Disclaimer
The information in this document is subject tochange without notice. bhi Ltd. makes norepresentations or warranties with respect to thecontents hereof and specifically disclaims anyimplied warranties of merchantability or fitness forany particular purpose. Furthermore, bhi Ltd.reserves the right to revise this publication and tomake changes from time to time in the contenthereof without obligation of bhi Ltd. to notify anyperson of such revision or changes.
Important Information
Page 39
8.3 NEIM1031 In-line module.Then NEIM1031 provides a flexible solution to noise reduction. Itfeatures both amplified inputs and outputs, along with line level sig-nal processing. The unit also features an audio bypass when theunit is switched off, so there is no need to disconnect when not inuse.
Features:• Fully adaptive noise cancellation 9 -35dB
• 8 user selectable noise cancellation levels
• Mono earpiece socket
• Input sensitivity control
• Noise cancellation On/Off switch
• Line level in/out
• Input overload indication
• Power on/off with audio bypass.
8.4 NEIM1031 accessories.
8.5 DSP modules.
LSPKR20 Watt extension speakerfor use with the NEIM1031.Fitted with a 3.5mm monojack plug.
1031-STAMounting stand for the NEIM1031.Allows the NEIM1031 to be ad-justed for the most comfortableoperating postion.
8.O
ther
bh
i pro
du
cts.
DSP module range.NEDSP1061: Low signal level moduleNEDSP1062 - KBD: Low signal level module
controlled by single buttonkeyboard.
NEDSP1062 - KBD: Amplified DSP modulecontrolled by a 2 buttonkeyboard.
1030-UKPA UK DC power adapter1030-EUPA European DC power adapter
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating Manual Page 3
1. Introduction1.1 NEDSP1062-KBD features 51.2 Limitations 51.3 Module connection and mounting 61.4 Keyboard mounting 71.5 Sounder mounting 81.6 DSP noise cancellation 9
2. Module description2.1 Block diagram 102.2 Module layout 112.3 Pin functions 112.4 Controls 12
2.4.1 PCB controls 122.4.2 Keyboard 12
2.5 Electrical characteristics 12
3. Installation3.1 Installation overview 163.2 Module setup 17
3.2.1 Overview 173.2.2 Suggested set up procedure 173.2.3 Changes to output load 183.2.4 Other signal considerations 18
3.3 Driving the module from a low level signal 19
4. Functions4.1 Keyboard 20
4.1.1 Power button 204.1.2 DSP level button 20
4.2 Set up 214.3 Demonstration modes 234.4 Noise cancellation levels 24
5. Application notes5.1 Yaesu SP8 255.2 Kenwood SP31 285.3 bhi label 31
Contents
Page 38
8. Other bhi productsOther noise cancellation products from bhi. Visit www.bhi-ltd.co.ukfor more information.
DSP noise cancellation built into a compactspeaker unit. the unit provides an easy toinstall solution to noise reduction
Features:• Fully adaptive noise cancellation 9 -35dB
• 8 user selectable noise cancellation levels
• Mono earpiece socket
• Input sensitivity control
• Noise cancellation On/Off switch
• LED indication of power and noise cancellation
• 12-24VDC operation
• On/Off audio bypass switch.
• Greatly improved signal to noise ratio
• Easy to install with adjustable mounting bracket
• 2m audio lead
• Optional extras avaiable.
8.1 NES10-2 MKII Noise Eliminating speaker.
Basic plug and go noise cancellingspeaker preset to 20dB of noisereduction.
Features:• Fully adaptive noise cancellation 20dB
• 12-24VDC operation
• Compact robust speaker unit.
• Greatly improved signal to noise ratio
• Easy to install with adjustable mounting bracket
• 2m audio lead
8.2 NES5 Noise Eliminating speaker.
8.O
ther
bh
i pro
du
cts.
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating ManualPage 4
6. Physical dimensions6.1 Physical dimensions 326.2 Keyboard hole drilling detail 35
7. TroubleshootingTroubleshooting 37
8. Other bhi productsOther bhi products 38
Page 37
Sta
rt
Incr
ease
input
leve
l
Ove
r lo
ad L
ED
illum
inate
s? N
o
Yes
Reduce
input
so L
ED
goes
out
Incr
ease
outp
ut
leve
l P1
Suffic
ient
outp
ut vo
lum
e?
Supply
volta
ge
<13.8
Vdc
Input le
vel
too lo
w
Incr
ease
supply
volta
ge
Fin
ish Y
es
Dis
connect
R6
(see s
ect
ion 3
.3)
Ove
r lo
ad L
ED
illum
inate
s?
Add a
dditi
onal
am
plif
icatio
n
No
Yes
No
No
Yes
7.2
Insu
ffuci
ent
outp
utvo
lum
e
7. Troubleshooting
Input
signal
Ove
rload
LE
D o
nR
educe
input
leve
l
Incr
ease
outp
ut le
vel
P1
Apply
audio
sig
nal
Incr
ease
input
signal
P2 N
o
Yes
No
Yes A
udio
out?
Fin
ish
Sta
rt Yes
No
7.1
No
audi
o ou
t
7.Tr
ou
ble
sho
oti
ng
.
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating Manual Page 5
1. Introduction.The NEDSP1061-KBD is a modular solution for noisereduction. It incorporates Digital Signal Processing (DSP)technology to provide up to 35dB of noise cancellationand 65dB of tone reduction. The module features an onboard power amplifier to allow it to be easily incorporatedin to existing equipment by installing the module in linewith the loudspeaker. All functions of the module arecontrolled by an easy to use keyboard.
1.1 NEDSP1062-KBD module features:
Fully adaptive noise cancellation up to 35dBInput and output level controlsInput level over load indicationVirtually no distortion to speech signalEasy to install4/8 levels of noise reduction (selectable)Frequency response 50Hz - 4.3KHz3 Watts output (4W)Single button operation of DSP mode with LED andaudible indication12 - 18V supply range27dB on board gainPower on/off - bypass pushbuttonSmall size 37 x 50mm (DSP pcb)Audio bypassed when power disconnectedSupplied with fixing and wiring kit and all labels
1.2 Limitations.This module is designed to pass speech. Other signalssuch as data, music and morse (CW) will to some degreepass through, but the integrity of these signalscannot be guaranteed. 1.
Intr
od
uct
ion
.
Page 36
<This page is intentionaly blank>
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating ManualPage 6
Figure 1. Mounting options
1.3 Module connection and mounting
The module is supplied with a pre-wired 2.1mm powerconnector. The centre pin is positive. The audio in andout are pre-wired pairs of wires, ready to be connectedin the audio path. The heatsink doubles up as a mountingbracket.
This module is designed to be driven from a high levelsignal, capable of driving a load of 22W.
(The module can be easily modified to be driven from alow power signal, see section 3.3 for more information).
The module can be mountedusing the supplied self adhesivefoam pad. Ensure that none ofthe circuit pins can make contactwith any metallic parts.
For improved heat dissipationand a more rigid mechanicalfixing the heatsink can bereversed and used as a bracket.Note that the heatsink is at 0Vpotential and therefore may have
to be electrically insulated from any other metallic parts.
Alternatively the module has fourfixing holes which allow it to befixed to pillars.(See section 6 for hole detailsand physical dimensions).
1.In
tro
du
ctio
n. Using the heatsink
as bracket
Self adhesivepad
Mounting usingPCB pillars
Page 35
6.P
hys
ical
dim
ensi
on
s.
6.2 Template.
The following drawing shows the sizes and positions ofholes for the keyboard.
Figure 36. Keyboard drilling detail .
Not to scaleall dimensions in mm
29.8
18.5
13.4
6.7
6.7
10.9
5.5
4mm4mm 4mm
3mm CSKto 5mm
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating Manual Page 7
1.In
tro
du
ctio
n.
If the installation has limitedspace, and is housed in a metalenclosure, the heatsink can beremoved, and the modulemounted directly on the chassis.The voltage regulator needs to becorrectly insulated as the tab isconnected to 0V. Insulate boththe regulator and mountingscrew. For improved heatdissipation use a suitable thermalpaste between the power devicesand the mounting.
Figure 2.Direct mounting.
Figure 3. Keyboard mounting 1.
The keyboard ismounted through theenclosure to providean easy to useinterface. Themodule is suppliedwith a label to placeover the keyboard.
When the enclosure is thick enough the keyboard isretained using a countersunk screw (supplied), which ishidden by the label, see figure 3 above. Do not overtighten the mounting screw.
keyboard
Front panellabel
Retainingscrew
Frontpanel
Insulator
Insulator
VoltageRegulator
1.4 Keyboard mounting.
(not supplied)
(not supplied)
Page 34
6.P
hys
ical
dim
ensi
on
s.
Figure 34. Keyboard dimensions.
Figure 35. Power connector hole size.
29.8
25.3
20.2
13.4
6.89.5
4.7
7.5
3.2
10
.9
5.53
8mm diameter
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating ManualPage 8
Figure 4.Keyboard mounting 2.
If the enclosure is toothin to incorporate acountersunk screw(such as fitting intosheet metal) then it canbe retained by ainstrument headscrew.The label needs to becut out to allow thescrew to pass throughfrom the outside. Thiscan be easily achievedby applying the label tothe panel, then carefully cutting around the screw hole,with a sharp knife. Again do not over tighten the screw.
Nut &washer
Front panellabel
keyboard
Retainingscrew
Frontpanel
1.5 Sounder mounting.
Cut a small piece of theself adhesive foam(supplied) to mount thesounder.Do not cover the smallhole in the face of thesounder.For best results mountthe sounder where itcan radiate sound tothe outside the case,for example on an airvent.
Figure 5. Sounder mounting
SounderBacking paper
Backingpaper
Self adhesivefoam
Case
Keep thishole clear
Cut holefor screw
1.In
tro
du
ctio
n.
Page 33
6.P
hys
ical
dim
ensi
on
s.Components fitted torear of PCB
Figure 32. Overall dimensions.
Figure 33. Hole dimensions of power devices - for directmounting applications.
16.1
5.3
17.9
16.4
Viewed fromthe end ofthe module
34.2
64.4
5.8
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating Manual Page 9
1.6 DSP Noise cancellation.
The bhi DSP processes the incoming signal and thendifferentiates the speech from the noise. The unwantednoise and interference is then attenuated to leave onlythe speech. The following diagrams are taken from actualaudio signals and illustrate how the signal is beingprocessed.
Figure 6. Noise cancellation.
Original signal.Speech with a lot ofbackground noise
Processed speech.Speech with reduced
noise
Speech Noise Reduced noise
1.In
tro
du
ctio
n.
Page 32
23.4
2.97
30.3
34.3
36.5
49.6
2.97Pin 1
3mm dia
6.P
hys
ical
dim
ensi
on
s. 6. Physical Dimensions
Figure 31. Mounting hole positions.
Top
6.1 Physical dimensions.The following diagrams detail the physical dimensionsof the module. All dimensions are in mm.
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating ManualPage 10
2. Module description.
Figure 7. NEDSP1062-KBD block diagram
1
3
8
Polarityprotection
Internalpull up
resistors
Input levelset
In 9
overloaddetect
Digital to analogueconversion
Output levelset
Power Amp
BCD DSP level select
Xtal
Clock generator
DSP core
5V5VRegulator
Latch
12V regulator
3.3V regulator
3.3V 12VRelayDrive
Relay 1
ON 14
Analogue to Digital conversion
70V
10
12
6
Power supplysection
PCBConnections
13
5
J3
InputLoad
resistor
Agnd
Agnd
Vin
NC
NO
NO
NCDSP
3V3 0V
PCB
microcontroller4
Keyboardinterface
8
N/C
N/C
Relay 1 Out
11
2.1 Block diagram.
2.M
od
ule
des
crip
tio
n.
Page 31
Figure 30. bhi label.
5.A
pp
licat
ion
s.
5.3 bhi Label.
Supplied with the module is a square bhi label. Fix thelabel on the top of the speaker enclosure as shown.
bhibhibhibhibhiDSP
NoiseCancellation
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating Manual Page 11
2.2 Module Layout.
The following diagram shows the layout of theNEDSP1062-KBD module.
Pin No. Name Description Notes
4 N/C Do not connect Not used
5 Vin Supply voltage 12 - 18VDC power in
6 N/C Do not connect Not used
7 0V 0V connection 0V power connections
9 In 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.M
od
ule
des
crip
tio
n.
Figure 8. NEDSP1062-KBD connections and controls
Inputlevel set
(P2)
Outputlevel set (P1)
Input overloadindicator LED
Mountingholes
Audiobypassrelay
The following table gives a description of the pin functions.
Note:Wiring obmitted for clarity
Soundervolume (P3)
2.3 Pin functions.
Page 30
Figure 29. Photograph of complete installation.
Sounder
NEDSP module(screwed to the case,using an existing hole)
Inputselectorswitch
FilterPCB
DSPconnections
Keyboard
5.A
pp
licat
ion
s.
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating ManualPage 12
2.4 Controls.
2.4.1PCB.The level controls provide adjustment for the audio levelsentering and leaving the module. The modules are factoryset to the maximum level.
Turning the potentiometers clock wise will decrease thelevels. These potentiometers do not have end stops, soit is possible to set them in a position where the audiowill be lost.
Audible indication of operation is provided by an piezosounder. The volume of this sounder can be varied bypotentiometer P3. The sounder volume is independentof the incoming audio volume.
2.4.2Keyboard.
The keyboard controls all of the module functionsincluding power on/off.
2.M
od
ule
des
crip
tio
n.
Figure 9. NEDSP1062-KBD keyboard.
Power button(power and
Audio bypass)
DSP levelbutton
Tri colourLED
Mounting hole
Page 29
5.A
pp
licat
ion
s.
NE
DS
P1
06
2
Lin
e o
ut
Input
Sele
ctor
Input
PC
B
Pow
er
Re
d
White
Bla
ck
Bro
wn
0V
Headphones
Filt
er
Blu
e
Bla
ck0V
Lin
e o
ut
Keyb
oard
Ye
llow
Ye
llow
43
125
12
3
12
21
43
Bla
ckB
lack
9 11
10
12
Connect
ions
to
module
Bla
ck
Re
d
Blu
eR
ed
Figure 28. Circuit diagram of installation in KenwoodSP31.
The
mod
ule
is in
sert
ed in
to t
he c
ircui
t be
fore
the
filt
er P
CB
. Id
entif
y th
e ye
llow
wire
conn
ectin
g th
e in
put s
elec
tor
switc
h to
the
filte
r bo
ard.
Bre
ak th
e w
ire a
nd c
onne
ctth
e N
ED
SP
1062
-KB
D a
s sh
own
belo
w.
Insu
late
the
wire
s w
ith t
he s
uppl
ied
rubb
ersl
eeve
s. I
dent
ify t
he b
lack
wire
fro
m t
he i
nput
PC
B a
nd c
onne
ct a
s sh
own
belo
w,
agai
n in
sula
ting
the
conn
ectio
ns.
The
fitt
ing
kit
incl
udes
cab
le t
ies
to t
idy
up t
hew
iring
of
the
inst
alla
tion.
The
pho
togr
aph
on t
he n
ext
page
sho
ws
the
com
plet
ein
stal
latio
n. M
ount
the
key
boar
d an
d po
wer
con
nect
or a
s sh
own
else
whe
re in
thi
sm
anua
l. T
he s
quar
e bh
i lab
el c
an b
e fit
ted
to t
he t
op o
f th
e ca
se.
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating Manual Page 13
2.5 Electrical characteristics.
Symbol Parameter Test Conditions Min. Typ. Max. Units
Vs
Supply voltage 12 16 18 V
Iqs
Quiescent currentV
s = 12V
Vs = 16V
Vs = 18V
4.66.87.1
mA
Iqon
Quiescent current DSP onno load no signal
Vs = 12V
Vs = 16V
Vs = 18V
143160161
mA
ELECTRICAL CHARACTERISTICS(V
s=16V, T
amb= 25
iiiiiC unless otherwise stated)
DC CHARACTERISTICS
AC CHARACTERISTICSSymbol Parameter Test Conditions Min. Typ. Max. Units
Po
Output power
d = 10%f = 1KHz
RL = 8W
RL = 4W
12V
1.161.7
16V 18V
2.063.17
Vs
WW
Vi
Input sensitivty4W load
f = 1KHzP
O = 0.5W
PO = 1.0W
PO = 2.0W
6090130
mV
Vi
Input sensitivty8W load
f = 1KHzP
O = 0.5W
PO = 1.0W
PO = 2.0W
81117180
mV
BFrequency response(-3dB)
Po = 1W
RL = 8W
50 4300 Hz
d Distortionf = 1KHzP
O = 0.2 - 2.4W R
L= 8W
PO = 0.2 - 2.4W R
L= 4W
0.80.8
%
Ri
Input resistance 21 22 23 W
Gv
Voltage gain f = 1KHz 27 dB
n Efficiencyf = 1KHzP
O = 3W R
L = 4W
PO = 2W R
L = 8W
3338
%
ANALOGUE CHARACTERISTICSSymbol Parameter Test Conditions Min Typ Max. Units
Td
System delay 26 mS
2.M
od
ule
des
crip
tio
n.
Table 2. Electrical characteristics 1
Page 28
5.A
pp
licat
ion
s.DSP
Keyboard5.2 Kenwood SP31.
Figure 25. NEDSP1062-KBD installed in a KenwoodSP31.
This sectiondescribes the generalfitting of theNEDSP1062-KBDmodule in theKenwood SP31loudspeaker. Thisinstallation retains theoperation of theinternal filters.
Figure 26. Suggestedlocation of keyboard.
Figure 27. Suggestedlocation of powerconnector.
Suggested location formounting the powerconnector
This photographshows thesuggested locationfor mounting thekeyboard.
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating ManualPage 14
-20
-15
-10
-5
0
5
0 1000 2000 3000 4000 5000 6000
Figure 10. Frequency response
Frequency (Hz)
Out
put (
dB)
0
2
4
6
8
10
12
0 0.5 1 1.5 2 2.5 3 3.5
Figure 11. Distortion vs. Output power
Dis
tort
ion
Output power (W)
VS = 16V
f = 1KHz RL = 8W
RL = 4W
2.M
od
ule
des
crip
tio
n.
RL = 8W
VS = 16V
P = 1W
-3dB
Page 27
Figure 24. Complete installation in the Yaesu SP8.
DSPmodule
InputPCB
Powerconnector
5.A
pp
licat
ion
s.
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating Manual Page 15
Figure 12. Sensitivity.
0
0.5
1
1.5
2
2.5
0 50 100 150 200
Input voltage (mV)
Out
put p
ower
(W
)
RL = 8W
RL = 4W
VS = 16V
f = 1KHz
2.M
od
ule
des
crip
tio
n.
Page 26
Figure 23. Circuit diagram of installation in Yaesu SP8.5.A
pp
licat
ion
s.
NE
DS
P1
06
2F
ilte
r u
nit
Sw
itch
un
itP
ho
ne
jack
unit
12
Bla
ck
Re
d
122 1
Ke
ybo
ard
connect
or
Bla
ckB
lack
9 11
12
10
Connect
ions
to
mo
du
le
JP2
00
2JP
30
01
Re
dB
lue
The
NE
DS
P10
62 m
odul
e in
thi
s ap
plic
atio
n is
inse
rted
bet
wee
n th
e fil
ter
unit
and
the
phon
e ja
ck u
nit.
Loca
te th
e 2
wire
con
nect
or o
n th
e sw
itch
unit
(JP
2002
). B
reak
the
wire
to p
in 1
and
wire
as
show
n in
the
dia
gram
. In
sula
te t
he c
onne
ctio
n w
ith t
he s
uppl
ied
rubb
er s
leev
e. B
reak
the
wire
on
pin
2 on
JP
2002
and
con
nect
as
show
n in
the
diag
ram
and
agai
n in
sula
te w
ith a
rub
ber
slee
ve. T
he f
ittin
g ki
t in
clud
es c
able
tie
s to
tid
y up
the
wiri
ng o
f the
inst
alla
tion.
The
pho
togr
aph
on th
e ne
xt p
age
show
s th
e co
mpl
ete
inst
alla
tion.
Mou
nt t
he k
eybo
ard
and
pow
er c
onne
ctor
as
show
n el
sew
here
in
this
man
ual.
The
squa
re b
hi la
bel c
an b
e fit
ted
to t
he t
op o
f th
e ca
se.
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating ManualPage 16
Figure 13. Basic connection diagram
3.1 Installation overview.
The NEDSP1062-KBD module is inserted into the pathof noisy audio. The input and output level controls allowthe module to be fine tuned to suit most applications.
3. Installation
Audio in
Power amp
+
-
Break Circuithere
Audio Out(Loudspeaker)
The input to the module is loaded at 22W to provide adummy load to the preceding circuit. This can be removedif required, such as using the module in applicationswhere the audio source is provided by a low level, lowpower signal source. More information on this can befound 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 rejectionratio will deteriorate. Best results are obtained in therange of 13.8V - 16Vdc.
Audio in
NEDSP1062Power amp
+
-
IN
Agnd Agnd
OUT
Keyboard
Power
10
12
9
11 Black
Piezosounder
BlueRed
Black
3.In
stal
lati
on
.
Page 25
5. Application Notes.
5.A
pp
licat
ion
s.
This section provides information into installing theNEDSP1062-KBD into Amateur radio speaker units.
Figure 20. NEDSP1062-KBDinstalled in a Yaesu SP8.
5.1 Yaesu SP8.This section describesthe general fitting ofthe NEDSP1062-KBDmodule in the YaesuSP8 loudspeaker. Thisinstallation retains theoperation of theinternal filters.
DSPKeyboard
Figure 21. Suggested location ofpower connector
Figure 22. Suggested locationof keyboard.
This photographshows thesuggested locationfor mounting thekeyboard.
Suggested location formounting the powerconnector
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating Manual Page 17
3.2 Module setup.
3.In
stal
lati
on
.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 LEDilluminates. 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.
To obtain the best results from the noise reduction themodule should be set up to give optimum performance.The input sensitivity control has a range of 0.70mW -3W to provide 2W (W)output.
Under certain conditions, RF breakthrough cansometimes occur. To minimize this, the input level (P2)may need to be reduced or go to the FAQ page on thebhi website and download the FAQ on RF breakthrough.
Under certain conditions the DSP can create a smallamount of noise, normally when the unit has no signalapplied. You should not be able to hear this noise whena signal is applied.
Both the input and output levels are adjustable on themodule. This allows easy integration into the target system.
3.2.1 Overview.
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4.O
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4.4 Noise reduction levels.
4 or 8 levels of noise reduction are available. The amountof noise and tone reduction is shown in the table below.
Level(4)
Level(8)
Tone Reduction White Noise Reduction
1 4dB 9dB
1 2 5dB 11dB
3 6dB 13dB
2 4 8dB 15dB
5 16dB 17dB
3 6 21dB 20dB
7 25dB 24dB
4 8 65dB 35dB
Table 4. Tone and noise reduction levels.
The column marked level (4) shows the noise and tonereduction when operating the module with 4 levels, andthe level (8) column for 8 levels.
Holding down the DSP select button will continuouslychange the DSP level. When the desired level has beenreached, release the button. The module will retain thislevel until it is changed.
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating ManualPage 18
The NEDSP1062-KBD requires a signal of 125mV rmsor greater for optimum performance. Signals lower thanthis may be used but the noise cancellation performancewill decrease, as the signal levels drops. If the unit isused with low level signals such as microphones, thesignal will need amplifying before applying it to theNEDSP1062-KBD.
Due to the adaptive nature of the noise cancellation asmall delay may be heard when the audio signalchanges. For optimum performance provide the modulewith a constant signal where possible.
When switching on the unit a thump may be heard in theloudspeaker.3.
Inst
alla
tio
n.
Figure 14. Input circuit -module powered down
22W
OUT
12Agnd
Agnd
9
10
V
AudioInput
NEDSP1062
R6
IN
Load
11
The audio input to themodule is loaded at22W. This load iseffectively connectedacross the output loadwhen the unit isswitched off(bypassed).This will reduce theimpedance presentedto the audio source.
For example:8W will reduce to 5.9W4W will reduce to 3.4W
3.2.3Change to output load.
3.2.4Other signal considerations.
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Start
Noise cancellationOn
Wait 1.5 Seconds
Noise cancellation off
HighestLevel?
Normal operation
No
Yes
Increase DSPnoise cancellation
level
Start
Noise cancellation off
Noise cancellationOn
Wait 3 Seconds
No
Yes
DSP buttonpressed?
2 tone beep
Normal operation
Wait 3 Seconds
Demonstration 2.The module switchesthe noise cancellationon for 3 seconds thenoff for 3 seconds. Thisis a good demonstra-tion of the before andafter effects of remov-ing the noise.
Demonstration 1.The module switches thenoise cancellation on for 1.5seconds, then off for 1.5seconds. It will then move tothe next level and repeat theprocess.This mode is particularlyeffective at demonstrating thedifferent DSP levels.Alternatively pass a cleanaudio signal through themodule to see hear how littlethe DSP alters the speech.
Note:To exit the demonstra-tion modes hold downthe DSP button until a2 tone beep is heard.
Figure 19.Demonstrationmodes.
4.3 Demonstration modes.
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating Manual Page 19
Figure 16. Circuit modification for low power signal drive.
3.3 Driving from a low signal source.
The input to the module has a low impedance. This is toprovide correct loading to any power circuits driving it. Ifthe module needs to be driven from a low power signalthen it must be modified in the following manner.
Cut theleg on this
resistor
3.In
stal
lati
on
.
22W
OUT
12Agnd
Agnd
9
10
LoadV
AudioInput
NEDSP1062
R6
IN
11
Circuitmodification
Figure 15. Physical modification for low power signaldrive.
Note:Wiring
omitted forclarity.
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To listen to the demonstration modes, or change thenumber of DSP levels it is necessary to put the moduleinto the set up mode.
To do this, ensure the module is Off. Press and hold theDSP level button. Turn on the module and a 2 tonebeep will be heard indicating that the module is in theset up mode.
Releasing the button after the first 2 tone beep will enterdemonstration mode 1.
Releasing after the second 2 tone beep will enterdemonstration mode 2.
Keeping the button depressed with change the numberof levels available. 4 beeps will indicate 4 level modeand 8 beeps 8 levels. Release the button when thedesired level is reached.
The module will return to normal operation after this.The colour of the LED will indicate the mode of operation.
DSP mode 4 Levels 8 Levels
OFF RED ORANGE
ON GREEN GREEN
Table 3. LED mode indication.
NEDSP1062-KBD Operating ManualNEDSP1062-KBD Operating ManualPage 20
4. Operation.4.
Op
erat
ion
.
4.1 Keyboard.The keyboard has 2 buttons and a tricolour LED.
4.1.1Power button.The power button switched the module on and off. Whenthe module is off, the audio bypasses the module, sothe circuit will behave as if the module isn’t present.Switching the power on routes the audio through themodule.
Note: If the power is on and the DSP is switched off, theaudio still passes through the DSP - but without any signalprocessing.A single press on the button switches on, and a singlepress will switch off. Also with the power connected andthe 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 levelbutton
Tri colourLED
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Power up
DSP buttonpressed
2 tone sound
DSP buttonpressed
2 tone sound
2 tone sound
Demonstration2
Demonstration1
No
Yes
No
Yes
No
Yes
DSP buttonpressed
DSP buttonpressed
2 tone sound
DSP buttonpressed
Change 4 or 8 levels
Normal operation
No
Yes beep numberof DSP levels
Yes No
DSP buttonpressed
Yes
No
4.O
per
atio
n.
4.2 Set up.The following flow chart shows the functions of the DSPbutton.
Releasing the DSP buttonat this point the modulegoes in to demonstrationmode 1
Keep the button downuntil the desired levelhas been reached, thenrelease the button. Themodule will continouslyscroll through 4 and 8levels until the button isreleased.
Figure 18. 4/8 level setting.
Holding down the DSPbutton when switching oncauses the module to enterthe set up mode.
This is indicated by a 2tone beep.
Releasing the DSP buttonat this point the modulegoes in to demonstrationmode 2