1062-106Diss b_web

NEDSP1062 Operating Manual

bhibhibhibhibhiNEDSP1062-PCB

Amplified Noise Eliminating DSP Module

Installation and Operating Manual

Sou

nd E

ngin

eerin

g S

olut

ions

from

bhi

1062-106DIssue B


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


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


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

.


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


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


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

.


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.


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-21

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otnip

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morftupnicigoL

51V0

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noitcennocV0

erapS

Table 1. NEDSP1062 connection functions

2.M

od

ule

des

crip

tion

.


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-

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V NO tupniNO dereggirtegdE 5 V

DIGITAL CHARACTERISTICS

2.M

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.

Table 2. Electrical characteristics 1


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

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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

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des

crip

tion

.

Table 3. Electrical characteristics 2


-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


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

.


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

.


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.


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.


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.


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


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.


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.


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


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.


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.


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.


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.


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.


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


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in 8

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at 3

.3V

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ed to

pi

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1 an

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Fini

sh

Yes

7.2

No

nois

e re

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7.Tr

oub

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oo

ting.

7. Troubleshooting


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

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tohi

gher

leve

l

Noi

se re

duct

ion

wor

king

?

Fini

sh Yes

No

Che

ck v

olta

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on N

0, N

1 an

d N

2ar

e w

ithin

lim

its

Sta

rt

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inpu

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r loa

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? 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

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volta

ge<1

3.8

Vdc

Inpu

t lev

elto

o lo

w

Incr

ease

supp

lyvo

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Fini

sh Yes

Dis

conn

ect

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(see

sec

tion

3.3)

Ove

r loa

d LE

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min

ates

?

Add

add

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alam

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No

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7.4

Insu

ffuci

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utpu

tvo

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7.Tr

oub

lesh

oo

ting.


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.• Greatly improved signal to noise ratio• Easy to install with adjustable mounting bracket• 2m audio lead• Optional extras avaiable.

8.1 NES10-2 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.

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8.3 NEIM1031 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• 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.

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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.


bhi ltdP.O. Box 318Burgess Hill

West SussexRH15 9RR

tel: +44 (0)845 217 9926fax: +44 (0)845 217 9936

[email protected]

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DSP Noise Cancellation

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