NEDSP1062 Operating ManualNEDSP1062 Operating Manual Page 1
bhibhibhibhibhiNEDSP1062-PCB
Amplified Noise Eliminating DSP Module
Installation and Operating Manual
DSP
Noi
se C
ance
lling
Pro
duct
s fr
om b
hi
1062-106DIssue C
Page 32
bhi Ltd22 Woolven Close
Burgess HillWest Sussex
RH15 9RR
tel: +44 (0)1444 870333
[email protected] www.bhi-ltd.com
bhibhibhibhibhiD
SP N
oise
Can
celli
ng P
rodu
cts
from
bhi
DSP Noise Cancellation
NEDSP1062 Operating ManualNEDSP1062 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 31
8.3 NEIM1031MKII In-line module.Then NEIM1031 provides a flexible solution to noise reduction. It fea-tures both amplified inputs and outputs, along with line level signalprocessing. The unit also features an audio bypass when the unit isswitched off, so there is no need to disconnect when not in use.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
8.4 NEIM1031 accessories.
8.5 DSP modules.
LSPKR4 Ohm 20 Watt extensionspeaker for use with theNEIM1031. Fitted with a3.5mm mono jack plug.
1031-STANDPerspex mounting stand for theNEIM1031. Enables the NEIM1031 tobe mounted for a more comfortableoperating postion.
8.O
ther
bh
i pro
du
cts.
DSP pcb 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.
• Power on/off with audio bypass.
NEDSP1062 Operating ManualNEDSP1062 Operating Manual Page 3
1. Introduction1.1 NEDSP1062 features 41.2 Limitations 41.3 Module connection and mounting 51.4 DSP noise cancellation 6
2. Module description2.1 Block diagram 72.2 Module layout 82.3 Pin functions 92.4 Controls 102.5 Electrical characteristics 10
3. Installation3.1 Installation overview 143.2 Module setup 15
3.2.1 Overview 153.2.2 Suggested set up procedure 153.2.3 Changes to output load 153.2.4 Other signal considerations 16
3.3 Driving the module from a low level signal 17
4. Functions4.1 Noise reduction levels 184.2 Setting different DSP levels 194.3 Remote setting of DSP level 194.4 Noise cancellation on/off 204.5 Power on/off
4.5.1 Using PSU 214.5.2 Using On/Off button 21
5. Application notes5.1 Noise cancellation indication 235.2 Remote adjustment of noise
cancellation level 24
6. Physical dimensions6.1 Physical dimensions 26
7. TroubleshootingTroubleshooting 28
8. Other bhi productsOther bhi products 30
Contents
Page 30
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• Compact robust speaker unit.• Power on/off audio bypass switch• Easy to install with adjustable mounting bracket• 2m audio lead• Optional extras avaiable.
8.1 NES10-2MKII 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 Operating ManualNEDSP1062 Operating ManualPage 4
1. Introduction.The NEDSP1062 is a modular solution for noise reduction.It incorporates Digital Signal Processing (DSP) technologyto provide up to 35dB of noise cancellation and 65dB oftone reduction. The module features an on board poweramplifier to allow it to be easily incorporated in to existingequipment by installing the module in line with theloudspeaker.
1.1 NEDSP1062 module features:
Fully adaptive noise cancellation to 35dBInput and output level controlsInput level over load indicationVirtually no distortion to speech signalEasy to install8 levels of noise reductionFrequency response 50Hz - 4.3KHz3 Watts output (4W)Noise cancellation can be preset or remotely setduring operation12 - 18V supply range27dB on board gainWide range of connection possibilitiesMounting holesAudio bypassed when power disconnectedSmall size 37 x 50mm
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 29
7.3
No
nois
ere
duct
ion
Usi
ngex
tern
al
cont
rol o
fle
vel
Set
to h
ighe
rle
vel
Che
ck n
oise
re
duct
ion
on
Sta
rt
No
Yes
Ens
ure
jum
pers
J5 s
et to
OFF
Cha
nge
tohi
gher
leve
l
Noi
se re
duct
ion
wor
king
?
Fini
sh Yes
No
Che
ck v
olta
ge
on N
0, N
1 an
d N
2ar
e w
ithin
lim
its
Sta
rt
Incr
ease
inpu
tle
vel
Ove
r loa
d LE
Dillu
min
ates
? N
o
Yes
Red
uce
inpu
tso
LE
D g
oes
out
Incr
ease
out
put
leve
l P1
Suf
ficie
ntou
tput
vol
ume?
Sup
ply
volta
ge<1
3.8
Vdc
Inpu
t lev
elto
o lo
w
Incr
ease
supp
lyvo
ltage
Fini
sh Yes
Dis
conn
ect
R6
(see
sec
tion
3.3)
Ove
r loa
d LE
Dillu
min
ates
?
Add
add
ition
alam
plifi
catio
n
No
Yes
No
No
Yes
7.4
Insu
ffuci
ent o
utpu
tvo
lum
e
7.Tr
oub
lesh
oo
ting.
NEDSP1062 Operating ManualNEDSP1062 Operating Manual Page 5
Figure 1. Mounting options
1.3 Module connection and mounting
Connections to the module are made by a row of 15 padsat the right hand side of the PCB. These pads are on a2.54mm (0.1”) pitch, which allows the use of standard pinheaders, PCB connectors and direct wiring. The heatsinkdoubles up as a mounting bracket.
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 mounted usingthe supplied self adhesive foampad. Ensure that none of the circuitpins can make contact with anymetallic 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 details andphysical dimensions).
1.In
tro
du
ctio
n.Using the heatsink
as bracket
Self adhesivepad
Mounting usingPCB pillars
Page 28
Inpu
tsi
gnal
Ove
rload
LE
D o
nR
educ
e in
put
leve
l
Incr
ease
ou
tput
leve
lP
1
App
lyau
dio
sign
al
Incr
ease
inpu
tsi
gnal
P2 N
o
Yes
No
Yes
Aud
io
out?
Fini
sh
Sta
rt Yes
No
7.1
No
audi
o ou
t
No
DS
PP
ower
on? Y
es
Ext
erna
l po
wer
con
trol
bein
g us
ed?
Che
ck 5
Vpu
lse
on p
in 1
4(O
N)
Ens
ure
Jum
per J
1 fit
ted
Sta
rt
No
Yes
Noi
se c
ance
llatio
n P
in 8
@3.
3V
No
Ens
ure
Pin
8is
at 3
.3V
Che
ck A
udio
in/o
ut0V
are
con
nect
ed to
pi
ns 1
1 an
d 12
Fini
sh
Yes
7.2
No
nois
e re
duct
ion
7.Tr
oub
lesh
oo
ting.
7. Troubleshooting
NEDSP1062 Operating ManualNEDSP1062 Operating ManualPage 6
1.4 DSP Noise cancellation.
The bhi DSP processes theincoming signal and thendifferentiates the speech from thenoise. The unwanted noise andinterference is then attenuated toleave only the speech.
Figure 3. 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.
If the installation has limited space,and is housed in a metal enclosure,the heatsink can be removed, andthe module mounted directly in asuitable position. The voltageregulator needs to be correctlyinsulated as the tab is connectedto 0V. Insulate both the regulatorand mounting screw. For improvedheat dissipation use a suitablethermal paste between the powerdevices and the mounting.
Figure 2.Direct mounting.
The following diagrams are taken from actual audio signalsand illustrate how the signal is being processed.
Insulator
Insulator
VoltageRegulator
(not supplied)
(not supplied)
Holesin
chassis
Page 27
6.P
hys
ical
dim
ensi
on
s.
34.2
64.4
5.8
Components fitted torear of PCB
Figure 23. Overall dimensions.
Figure 24. Hole dimensions of power devices - for directmounting applications.
16.1
5.3
17.9
16.4
Viewed fromthe end ofthe module
NEDSP1062 Operating ManualNEDSP1062 Operating Manual Page 7
2. Module description.
Figure 4. NEDSP1062 block diagram
1
2
3
8
Polarityprotection
Internalpull up
resistors
N0
N1
N2
Noff
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
DSPLevel set jumpers
70V
10Out
12
4
6
LatchDisable jumper
J1
Power supplysection
PCBConnections
13
5
J3
6
1
3
5
2
J5
4
InputLoad
resistor
Agnd
Agnd
Vin
NC
NO
NO
NCDSP
3V3 0V
PCB
Relay 1
N/C
N/C
11
2.1 Block diagram.
2.M
od
ule
des
crip
tion
.
Page 26
23.4
2.97
30.3
34.3
36.5
49.6
2.97 Pin 1
3mm dia
6.P
hys
ical
dim
ensi
on
s. 6. Physical Dimensions
Figure 22. Mounting hole positions.
Top
6.1 Physical dimensions.The following diagrams detail the physical dimensions ofthe module. All dimensions are in mm.
NEDSP1062 Operating ManualNEDSP1062 Operating ManualPage 8
2.2 Module Layout.
The following diagram shows the layout of theNEDSP1062 module.
2.M
od
ule
des
crip
tion
.
Moduleconnections (J3)
Figure 5. NEDSP1062 connections and controls
Powerbypassjumper
(J1)
DSPlevel selection
jumpers(J5)
Inputlevel set
(P2)
Outputlevel set (P1)
Input overloadindicator LED
Mountingholes
Pin 1
Audiobypassrelay
Table 1 on the following page gives a description of the pinfunctions.
Page 25
N0 1N1 2N2 3
0V 7
micro controllerNEDSP 1062
Figure 20. Control using a microcontroller
The module can be controlled with a microcontroller. Asthe DSP employs internal pull ups, it is not necessary todrive the microcontroller port pins high, they can beplaced in a high impedance state.
N0 1N1 2N2 3 micro controller
abcdefg
display
BCD to 7 segment
decoderCD4511
A
B
C
0V
Seven segment LEDdisplay showing DSP filter level
(note: displays 0 - 7)
Keyboard
Noff 8
NEDSP 1062
Figure 21. Control using a microcontroller with displayand keyboard.
The following example employs a 7 segment display andkeyboard. Noise on/off is also controlled by themicrocontroller. In the diagram 3 buttons are used, uplevel, down level and DSP on/off.
5.A
pp
licat
ion
s.
NEDSP1062 Operating ManualNEDSP1062 Operating Manual Page 9
.o
Nni
Pe
maN
noit
pircseD
seto
N
10
Ntib
noitallecnacesion
BSL
DC
Bretlif
PS
Dehttes
yletomer
otdes
Uneht
desuera
snipesehtfI.level
)6-5(
&)4-3(,)2-1(5J
srepmuj
evomer
21
Ntib
noitallecnacesion
DC
B
32
NB
SM
noitallecnacesion
DC
B
4C/
Ntcennocton
oD
desutoN
5ni
Vegatlov
ylppuS
nire
wopC
DV81
-21
6C/
Ntcennocton
oD
desutoN
7V0
noitcennocV0
snoitcennocre
wopV0
8ffo
Nnipffo/no
noitallecnacesio
Neht
stibihniV0
otnip
sihtgnitcenno
Cnepo
nipsiht
evaeL.noitallecnacesion
.nonoitallecnac
esionrof
9nI
tupnioid u
Adessecorp
ebot
nilangisoidu
A
01tu
Otuptuo
oiduA
tuolangisoidua
desecorP
11dng
Alangis
oiduatupnirof
V0ni
oiduarof
dnuorgeugolan
A
21dng
Alangis
oiduatuptuorof
V0tuo
oiduarof
dnuorgeugolan
A
31V5
desufihcti
wsno
rewop
rofylppus
V5lanretxe
gnisurof
-tuoegatlov
cigoLhcti
wsre
wop
41n
Odesufi
hctiws
nore
woproftupni
cigoLdesufi
hctiwslanretxe
morftupnicigoL
51V0
V0lanoitiddA
noitcennocV0
erapS
Table 1. NEDSP1062 connection functions
2.M
od
ule
des
crip
tion
.
Page 24
5.2 Remote adjustment of noise cancellationlevel.
N0 1N1 2N2 3
0V 7
0V
C
1 2 4
BCDComplement
switch
NEDSP 1062
This page illustrates various options for altering the DSPlevel remotely, during operation.
Figure 18. Basic setting using a BCD switch
N0 1N1 2N2 3
0V 7
1 2 4
0V
Note:Inputs
will be inverted
N0
N1
N2
NEDSP 1062
Figure 19. Basic setting using transistors
The transistors allowinterfacing with highervoltages to control the DSPlevel. These could bereplaced by opto couplers forgreater isolation.
5.A
pp
licat
ion
s.
NEDSP1062 Operating ManualNEDSP1062 Operating ManualPage 10
2.4 Controls.
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, so itis possible to set them in a position where the audio willbe lost.
2.5 Electrical characteristics.
ELECTRICAL CHARACTERISTICS(Vs=16V, Tamb= 25iiiiiC unless otherwise stated)
lobmyS retemaraP snoitidnoCtseT .niM .pyT .xaM stinU
V hgiHtuOlatigidlevelhgiH
egatlovtuptuo I hgiHO Am4.0= V dd 7.0- V dd V
V wolOlatigidlevelwoL
egatlovtuptuo I wolO Am4.0-= 0 2.0 4.0 V
I O tnerrucegakaeltuptuO 03 mA
R LDC LD
)latigid(daoltuptuO 102
KWFp
V hgiHniegatlovtupnilevelhgiH
)reggirtttimcS( 3.3 V
V woLniegatlovtupnilevelwoL
)reggirtttimcS( 8.0 V
I hgiHiI woli
tnerrucegakaeltupnI ddV=niVV0=niV
0103-
0303-
0606-
mA
V NO tupniNO dereggirtegdE 5 V
DIGITAL CHARACTERISTICS
2.M
od
ule
des
crip
tion
.
Table 2. Electrical characteristics 1
Page 23
5. Application Notes.
5.1 Noise cancellation On/Off indication.
Figure 17. Red/Green LED indication of noisecancellation.
In the above example separate Red and Green LEDs areused to give a visual indication of the noise cancellationmode. The green LED will illuminate when the noisecancellation is on, and the red when off. A single tricolourLED could also be used.
The switch could be replaced by a relay if remote operationis required.
0V 7
Noff 8
+V
0V
Red Green
R1 R2
Noise cancellation
Off
DPDT switch
NEDSP 1062
5.A
pp
licat
ion
s.
NEDSP1062 Operating ManualNEDSP1062 Operating Manual Page 11
lobmyS retemaraP snoitidnoCtseT .niM .pyT .xaM stinU
Vs egatlovylppuS 21 61 81 V
qI s tnerructnecseiuQVs V21=Vs V61=Vs V81=
6.48.61.7
Am
qI nonoPSDtnerructnecseiuQ
langisondaolon
Vs V21=Vs V61=Vs V81=
341061161
Am
DC CHARACTERISTICS
AC CHARACTERISTICSlobmyS retemaraP snoitidnoCtseT .niM .pyT .xaM stinU
Po rewoptuptuO
%01=dzHK1=f
RL 8= WWWWWRL 4= WWWWW
V21
61.17.1
V61 V81
60.271.3
Vs
WW
ViytvitisnestupnI
4WWWWW daol
zHK1=fPO W5.0=PO W0.1=PO W0.2=
0609031
Vm
ViytvitisnestupnI
8WWWWW daol
zHK1=fPO W5.0=PO W0.1=PO W0.2=
18711081
Vm
B esnopserycneuqerF)Bd3-(
Po W1=RL 8= WWWWW
05 0034 zH
d noitrotsiDzHK1=f
PO RW4.2-2.0= L 8= WWWWWPO RW4.2-2.0= L 4= WWWWW
8.08.0
%
Ri ecnatsisertupnI 12 22 32 WWWWW
Gv niagegatloV zHK1=f 72 Bd
n ycneiciffEzHK1=f
PO RW3= L 4= WWWWWPO RW2= L 8= WWWWW
3383
%
ANALOGUE CHARACTERISTICSlobmyS retemaraP snoitidnoCtseT niM pyT .xaM stinU
Td yaledmetsyS 62 Sm
2.M
od
ule
des
crip
tion
.
Table 3. Electrical characteristics 2
Page 22
Applying 5V to the ON input will alternatively switch thepower ON then OFF. This is input is edge triggered, sothe pin has to return to 0V before it can accept anotherlatch input. The input is internally debounced to preventmultiple operations is it is driven by a noisy switch.
Note:When the module is in the OFF state it draws a quiescentcurrent of typically 6mA.
The signal to control the power to the module can comefrom a simple non latching push button, or be driven fromexternal circuitry.
4.Fu
nct
ion
s.
Figure 16. Power switching waveform.
0V
5V
0FF
0N
Module power
ON pin input
Power onlychanges state on
transition fromlow - high(0V - 5V)
Multiple transistionsare internally debounced.
NEDSP1062 Operating ManualNEDSP1062 Operating ManualPage 12
-20
-15
-10
-5
0
5
0 1000 2000 3000 4000 5000 6000
Figure 6. 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 7. Distortion vs. Output power
Dis
torti
on
Output power (W)
VS = 16Vf = 1KHz RL = 8W
RL = 4W
2.M
od
ule
des
crip
tion
.
RL = 8WVS = 16V
P = 1W
-3dB
Page 21
4.5 Power On/Off.
The NEDSP1062 features a relay to remove the powerfrom the module and at the same time bypass the audiosignal. This isolates the module from the target system.This relay can be controlled in 2 ways.
NEDSP1062
ON 14 5V Logic
4.5.2 On/Off button.The module has a latch input that allows it to be controlledby a single momentary push button or external logic signal.Remove jumper J1 from the PCB.
NEDSP1062
ON 14
+5V 13External
(momentary)power button
Figure 14. Jumper J1.
Figure 15. Examples of external power switching.
4.5.1 Module powers up with PSU.The module can power up from thepower supply and will connect the audiosignal through the module. When thepower is removed (or fails) the audio willbypass the module. Ensure that JP1 isfitted. J1 is located near the black relay,in the top righthand corner of themodule.
4.Fu
nct
ion
s.
External controllogic
Removejumper or
placeover 1 pin
NEDSP1062 Operating ManualNEDSP1062 Operating Manual Page 13
Figure 8. Sensitivity.
0
0.5
1
1.5
2
2.5
0 50 100 150 200Input voltage (mV)
Out
put p
ower
(W)
RL = 8W
RL = 4W
VS = 16Vf = 1KHz
2.M
od
ule
des
crip
tion
.
Page 20
leveL 2N 1N 0N
1 V0 V0 V0
2 V0 V0 V3.3
3 V0 V3.3 V0
4 V0 V3.3 V3.3
5 V3.3 V0 V0
6 V3.3 V0 V3.3
7 V3.3 V3.3 V0
8 V3.3 V3.3 V3.3
Note:The DSP has internal pull ups on its inputs, so any cellin the table containing 3.3V may be left open circuit.When processing signals with high levels of noise andhigh levels of noise cancellation, the signal may soundslightly strange. This is quite normal with this type ofsignal.
4.4 Noise Cancellation On/OffThe module has the provision for remotely enabling anddisabling the noise cancellation, while in operation. Thedefault setting for the module is noise cancellation on.This may be switched by the use of the noise cancellationon/off pin (PCB pin 8).
To inhibit noise cancellation, connect this pin to 0V.To enable noise cancellation leave the pin unconnected.
Table 6. Remote DSP level setting.
4.Fu
nct
ion
s.
NEDSP1062 Operating ManualNEDSP1062 Operating ManualPage 14
Figure 9. Basic connection diagram
3.1 Installation overview.
The NEDSP1062 module is inserted into the path of noisyaudio. The input and output level controls allow the moduleto 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 applications wherethe audio source is provided by a low level, low power signalsource. More information on this can be found in section3.3 in this operating manual.
If Vin is less than approx. 13.8V ensure the power supply iswell decoupled otherwise the power supply rejection ratiowill deteriorate. Best results are obtained in the range of13.8V - 16Vdc.
Audio in
NEDSP1062Power amp
+
-
Dummyinput load
IN
Agnd Agnd
OUT
+V 0V
75
9 10
11 12
3.In
stal
lati
on
.
Page 19
leveL )6-5(5J )4-3(5J )2-1(5J
1 nO nO nO
2 nO nO ffO
3 nO ffO nO
4 nO ffO ffO
5 ffO nO nO
6 ffO nO ffO
7 ffO ffO nO
8 ffO ffO ffO
4.3 Remote setting of DSP filter level.
Remote setting of the DSP level can also be achievedthrough PCB connections on J3. This allows the DSP filterlevel to be changed during operation. If remote DSP settingis used, remove the jumpers from J5 on the module or setthem into the OFF position by placing them over one pinon the jumper.
These connections are connected directly to the DSP, donot apply voltages greater than 3.3V to these pins.To set the DSP level remotely connect the pins N0, N1and N2 (J3 pins 1,2, and 3) as shown on the following page.
Table 5. Preset DSP levels using on board jumpers.
4.2 Setting different filter levels.
The DSP levels are set by the following combination ofjumpers.
4.Fu
nct
ion
s.
NEDSP1062 Operating ManualNEDSP1062 Operating Manual Page 15
3.2 Module setup.
Both the input and output levels are adjustable on themodule. This allows easy integration into the target system.
3.2.1 Overview.
To obtain the best results from the noise reduction themodule should be set up with the maximum input level andthe minimum output level.The input sensitivity control has a range of 0.70mW - 3Wto provide 2W (W)output.
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 when asignal is applied.
3.In
stal
lati
on
.
3.2.2 Suggested set up procedure:
Basic setup procedure.Connect input source and output device.Ensure the NEDSP1062 is switched off.Set the audio source to a typical audio level.Switch on the NEDSP1062.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.
It should be possible to set all the levels such that when themodule is switched on and off, there isn’t a significantchange in the audio level.
Page 18
4. Functions.4.1 Noise reduction levels.
8 levels of noise reduction are available. The amount ofnoise and tone reduction is shown in the table below.
leveL noitcudeRenoT esioNetihWnoitcudeR
1 Bd4 Bd9
2 Bd5 Bd11
3 Bd6 Bd31
4 Bd8 Bd51
5 Bd61 Bd71
6 Bd12 Bd02
7 Bd52 Bd42
8 Bd56 Bd53
Table 4. Tone and noise reduction levels.
Figure 13. J5 detail.
two pins the jumper is ON.When the jumper isconnected to one pin only ,or removed from the board itis OFF. To reduce the risk oflosing the jumper it isadvised to place it on one pinwhen using the OFF position.
The DSP level is set by 3 jumpers. This is identified as J5on the circuit board. When the jumper is placed over the
4.Fu
nct
ion
s.
J5 pinsON
OFF2356
1
NEDSP1062 Operating ManualNEDSP1062 Operating ManualPage 16
The NEDSP1062 requires a signal of 125mV rms orgreater for optimum performance. Signals lower than thismay be used but the noise cancellation performance willdecrease, as the signal levels drops. If the unit is usedwith low level signals such as microphones, the signal willneed amplifying before applying it to the NEDSP1062.
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 maybe heard in theloudspeaker.
3.In
stal
lati
on
.
Figure 10. 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 is switchedoff (bypassed).This will reduce theimpedance presented tothe audio source.
For example:8W will reduce to 5.9W4W will reduce to 3.4W
3.2.3 Change to output load.
3.2.4 Other signal considerations.
Page 17
Figure 12. 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 11. Physical modification for low power signaldrive.