NATO UNCLASSIFIED 1 [email protected] The NATO Post-2000 Narrow Band Voice Coder: Test and Selection...

1NATO UNCLASSIFIED

[email protected]

The NATO Post-2000The NATO Post-2000Narrow Band Voice Coder: Narrow Band Voice Coder:

Test and Selection of Test and Selection of STANAG 4591STANAG 4591

The NATO Post-2000The NATO Post-2000Narrow Band Voice Coder: Narrow Band Voice Coder:

Test and Selection of Test and Selection of STANAG 4591STANAG 4591

CIS Division, NATO C3 AgencyCIS Division, NATO C3 AgencyCIS Division, NATO C3 AgencyCIS Division, NATO C3 Agency

Technical Presentation-001Technical Presentation-001Technical Presentation-001Technical Presentation-001

2 NATO UNCLASSIFIED

Abstract and Conditions of ReleaseAbstract and Conditions of ReleaseAbstract and Conditions of ReleaseAbstract and Conditions of Release

AbstractAbstract The work described in this presentation was carried out under customer

funded projects 25.12.00 and N.25.12.00, conducted by NC3A on behalf of AC322(SC/6-AHWG/3).

This presentation gives a general introduction to the work, which is documented in NC3A Technical Note-881 and NC3A Technical Memorandum-946.

This presentation is a working paper that may not be cited as representing formally approved NC3A opinions, conclusions or recommendations.

AbstractAbstract The work described in this presentation was carried out under customer

funded projects 25.12.00 and N.25.12.00, conducted by NC3A on behalf of AC322(SC/6-AHWG/3).

This presentation gives a general introduction to the work, which is documented in NC3A Technical Note-881 and NC3A Technical Memorandum-946.

This presentation is a working paper that may not be cited as representing formally approved NC3A opinions, conclusions or recommendations.

3 NATO UNCLASSIFIED

NC3A-NL, The Hague NC3A-BE, BrusselsScientific staff Acquisition staff

Set up voice coding testbed Equipment AcquisitionProcess input data Contractual issuesBlind and deblind dataSupport to AHWG NBVC, test labs and coder developers

NATO InfrastructureCommittee

NATO Narrow Band Voice Coder Ad-Hoc Working Group

NBVC and NC3ANBVC and NC3ANBVC and NC3ANBVC and NC3A

Customers

Customerfunded

Voice coder developers

Host Nation

4 NATO UNCLASSIFIED

Introduction to STANAG 4591Introduction to STANAG 4591Introduction to STANAG 4591Introduction to STANAG 4591

5 NATO UNCLASSIFIED

BackgroundBackgroundBackgroundBackground

• Voice Coding technology is constantly improvingVoice Coding technology is constantly improving• driven by mobile telephonydriven by mobile telephony

–narrow bandnarrow band–wireless channelswireless channels

• new coders outperform existing NATO voice codersnew coders outperform existing NATO voice coders

• Voice Coding technology is constantly improvingVoice Coding technology is constantly improving• driven by mobile telephonydriven by mobile telephony

–narrow bandnarrow band–wireless channelswireless channels

• new coders outperform existing NATO voice codersnew coders outperform existing NATO voice coders

STANAG 4209 - CVSD+ good resilience to noise- poor speech quality in no noise- high rate (16 k)

STANAG 4198 - LPC10e + low rate (2.4k)- low speech quality- low resilience to noise

• AHWG NBVC tasked by NATO to select a future AHWG NBVC tasked by NATO to select a future Narrow Band Voice Coder for NATO use at Narrow Band Voice Coder for NATO use at 1.2kbps and 2.4kbps1.2kbps and 2.4kbps

• AHWG NBVC tasked by NATO to select a future AHWG NBVC tasked by NATO to select a future Narrow Band Voice Coder for NATO use at Narrow Band Voice Coder for NATO use at 1.2kbps and 2.4kbps1.2kbps and 2.4kbps

6 NATO UNCLASSIFIED

Voice Coders TestedVoice Coders TestedVoice Coders TestedVoice Coders Tested• NATO requested candidates to be submitted by member NATO requested candidates to be submitted by member

nationsnations

• Three candidates submittedThree candidates submitted

• NATO requested candidates to be submitted by member NATO requested candidates to be submitted by member nationsnations

• Three candidates submittedThree candidates submitted

• FranceFrance• HSX (Harmonic Stochastic eXcitation)HSX (Harmonic Stochastic eXcitation)• FranceFrance• HSX (Harmonic Stochastic eXcitation)HSX (Harmonic Stochastic eXcitation)

• TurkeyTurkey• SB-PLC (Split-Band Linear Predictive Coding)SB-PLC (Split-Band Linear Predictive Coding) • TurkeyTurkey

• SB-PLC (Split-Band Linear Predictive Coding)SB-PLC (Split-Band Linear Predictive Coding)

• USAUSA• MELP (Mixed Excitation Linear Prediction)MELP (Mixed Excitation Linear Prediction)

• USAUSA• MELP (Mixed Excitation Linear Prediction)MELP (Mixed Excitation Linear Prediction)

(each candidate operates at (each candidate operates at both 1.2k & 2.4k)both 1.2k & 2.4k)

• plus LPC-10e (2.4k) CELP (4.8k) CVSD (16k) plus LPC-10e (2.4k) CELP (4.8k) CVSD (16k) as as known reference codersknown reference coders

(each candidate operates at (each candidate operates at both 1.2k & 2.4k)both 1.2k & 2.4k)

• plus LPC-10e (2.4k) CELP (4.8k) CVSD (16k) plus LPC-10e (2.4k) CELP (4.8k) CVSD (16k) as as known reference codersknown reference coders

7 NATO UNCLASSIFIED

Test Resources and ResponsibilitiesTest Resources and ResponsibilitiesTest Resources and ResponsibilitiesTest Resources and Responsibilities

• NC3A ran raw audio data through coders NC3A ran raw audio data through coders and ‘blinded’ all outputand ‘blinded’ all output

• National test labs analysed raw audio from National test labs analysed raw audio from NC3A. Test labs were:NC3A. Test labs were:• TNO, NLTNO, NL• CELAR, FRCELAR, FR• Arcon, USArcon, US

• NC3A impartially collated resultsNC3A impartially collated results

• NC3A ran raw audio data through coders NC3A ran raw audio data through coders and ‘blinded’ all outputand ‘blinded’ all output

• National test labs analysed raw audio from National test labs analysed raw audio from NC3A. Test labs were:NC3A. Test labs were:• TNO, NLTNO, NL• CELAR, FRCELAR, FR• Arcon, USArcon, US

• NC3A impartially collated resultsNC3A impartially collated results

• Project was ‘customer funded’ by Project was ‘customer funded’ by NATO Infrastructure Committee and NATO Infrastructure Committee and nations submitting codersnations submitting coders

• NC3A host nation, but worked with NC3A host nation, but worked with specialist speech processing labsspecialist speech processing labs

• Project was ‘customer funded’ by Project was ‘customer funded’ by NATO Infrastructure Committee and NATO Infrastructure Committee and nations submitting codersnations submitting coders

• NC3A host nation, but worked with NC3A host nation, but worked with specialist speech processing labsspecialist speech processing labs

The TNO test laboratory at Soesterberg, NL

NATO data being analysed at TNO

8 NATO UNCLASSIFIED

NATO NBVC testsNATO NBVC testsPhase 1Phase 1

NATO NBVC testsNATO NBVC testsPhase 1Phase 1

• Floating Point vocoder implementationsFloating Point vocoder implementations

• PerformancePerformance• IntelligibilityIntelligibility• QualityQuality

• Noise ConditionsNoise Conditions• QuietQuiet• Modern officeModern office• Acoustic noise, (6 dB, 12 dB)Acoustic noise, (6 dB, 12 dB)

• 5488 Mb of processed audio in 5848 files5488 Mb of processed audio in 5848 files

• Floating Point vocoder implementationsFloating Point vocoder implementations

• PerformancePerformance• IntelligibilityIntelligibility• QualityQuality

• Noise ConditionsNoise Conditions• QuietQuiet• Modern officeModern office• Acoustic noise, (6 dB, 12 dB)Acoustic noise, (6 dB, 12 dB)

• 5488 Mb of processed audio in 5848 files5488 Mb of processed audio in 5848 filesA typical test booth where subjects

listen to speech for analysis

9 NATO UNCLASSIFIED

Processing by NC3AProcessing by NC3AProcessing by NC3AProcessing by NC3A

Nine raw

audio output files

Sent to test labs for analysis

Encode Decode

CELP

FR1200

FR2400

CVSD

LPC10e

TU1200

TU2400

US1200

US2400

CELP

FR1200

FR2400

CVSD

LPC10e

TU1200

TU2400

US1200

US2400

BITSTREAM

CELP

FR1200

FR2400

CVSD

LPC10e

TU1200

TU2400

US1200

US2400

CELP

FR1200

FR2400

CVSD

LPC10e

TU1200

TU2400

US1200

US2400

123456789

Raw audio file

8kHz sample rate,

16 bit samples

10 NATO UNCLASSIFIED

Double blinding processDouble blinding processDouble blinding processDouble blinding process

CELP

FR1200

FR2400

CVSD

LPC10e

TU1200

TU2400

US1200

US2400

To test lab

Nine audio output files

Vocoder3

Vocoder4

Vocoder5

Vocoder2

Vocoder1

Vocoder6

Vocoder7

Vocoder8

Vocoder9

Decoded output

files

Double blinded

files

B

L

I

N

D

Coder3

Coder4

Coder5

Coder2

Coder1

Coder6

Coder7

Coder8

Coder9

Single blinded

files

B

L

I

N

D

Blinded by NC3A

Blinded by DSTL

LPC10e

Coder7

Vocoder9


17

Modulated Noise Reference UnitModulated Noise Reference UnitModulated Noise Reference UnitModulated Noise Reference Unit

CELPFR1200FR2400

CVSDLPC10e

TU1200TU2400US1200US2400

One raw audio file

Nine raw audio output files

CELPFR1200FR2400

CVSDLPC10e

TU1200TU2400US1200US2400

BITSTREAM

MNRU 15dB

MNRU 20dB

MNRU 25dB

MNRU 10dB

MNRU 5db

MNRU 30dB

MNRU 35dB

MNRU 40dB

•MNRU is a standard method to apply known levels of noise. It provides known references against which

listeners can compare vocoder outputs

MNRU 15dB

MNRU 20dB

MNRU 25dB

MNRU 10dB

MNRU 5db

MNRU 30dB

MNRU 35dB

MNRU 40dB

161514131211171017 raw audio output files.

MNRU files to test labs as references for analysing speech quality


NATO NBVC testsNATO NBVC testsPhase IIPhase II

NATO NBVC testsNATO NBVC testsPhase IIPhase II

• Fixed point implementationFixed point implementation

•CC plus ETSI libraries plus ETSI libraries

• Performance MeasurementsPerformance Measurements

• Intelligibility, QualityIntelligibility, Quality

• Speaker recognitionSpeaker recognition

• Language dependency Language dependency

–English, French, German, English, French, German, Dutch, Polish, TurkishDutch, Polish, Turkish

• Fixed point implementationFixed point implementation

•CC plus ETSI libraries plus ETSI libraries

• Performance MeasurementsPerformance Measurements

• Intelligibility, QualityIntelligibility, Quality

• Speaker recognitionSpeaker recognition

• Language dependency Language dependency

–English, French, German, English, French, German, Dutch, Polish, TurkishDutch, Polish, Turkish

• 10 acoustic noise 10 acoustic noise environmentsenvironments

• Transmission channelTransmission channel• 1% BER1% BER

• TandemTandem• 16 kbps CVSD - vocoder16 kbps CVSD - vocoder

• Whispered speechWhispered speech

• 10 acoustic noise 10 acoustic noise environmentsenvironments

• Transmission channelTransmission channel• 1% BER1% BER

• TandemTandem• 16 kbps CVSD - vocoder16 kbps CVSD - vocoder

• Whispered speechWhispered speech


Phase 2 additional test conditionsPhase 2 additional test conditionsPhase 2 additional test conditionsPhase 2 additional test conditions

Coder nAudio input file

Audio output file

Decoder nBitstream

1% random bit errors

Audio input file

CVSDCoder

Audio output file

Decoder nCoder nCVSDDecoder

Test configuration: 1% Bit error rate

Test configuration: Voice coder tandem

B i t s

B i t s

Audio


NATO NBVC tests - Phase 2NATO NBVC tests - Phase 2

Noise Conditions

Phase 1 plus ……..

NATO NBVC tests - Phase 2NATO NBVC tests - Phase 2

Noise Conditions

Phase 1 plus ……..

HMMWV Bradley Fighting Vehicle Le Clerc Tank Volvo (staff car)

MCE field shelter

Blackhawk helicopter Mirage 2000 F-15


NATO NBVC Phase 2NATO NBVC Phase 2NATO NBVC Phase 2NATO NBVC Phase 2

• Over 36,000 filesOver 36,000 files

• Over 30 GB of processed speech dataOver 30 GB of processed speech data

• 500 hours of speech 500 hours of speech

–Some voice coders ran approx 10 times real timeSome voice coders ran approx 10 times real time

• Over 36,000 filesOver 36,000 files

• Over 30 GB of processed speech dataOver 30 GB of processed speech data

• 500 hours of speech 500 hours of speech

–Some voice coders ran approx 10 times real timeSome voice coders ran approx 10 times real time

3 test labs

x 5 tests x 12 noise conditions

x 9 coders (+ 8 MNRU levels)

x 88 files per test


Need for Precision Weighted RankingNeed for Precision Weighted RankingNeed for Precision Weighted RankingNeed for Precision Weighted Ranking

• Graphs show variation Graphs show variation between intelligibility tests between intelligibility tests performed by the 3 test performed by the 3 test labslabs• General trends are the General trends are the

samesame• Absolute scores varyAbsolute scores vary

• Need to combine all Need to combine all results accurately and results accurately and fairlyfairly• Simple scaling is not Simple scaling is not

sufficientsufficient

• Graphs show variation Graphs show variation between intelligibility tests between intelligibility tests performed by the 3 test performed by the 3 test labslabs• General trends are the General trends are the

samesame• Absolute scores varyAbsolute scores vary

• Need to combine all Need to combine all results accurately and results accurately and fairlyfairly• Simple scaling is not Simple scaling is not

sufficientsufficient

Quiet

50.0

55.0

60.0

65.0

70.0

75.0

80.0

85.0

90.0

95.0

100.0

1 2 3 4 5 6 7 8 9

Arcon

CELAR

TNO

BlackHawk

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

1 2 3 4 5 6 7 8 9

Arcon

CELAR

TNO

US24 CELP FR24 CVSD TU24 US12 LPC TU12 FR12



Score vs Interval

y = 0.0341x + 0.1949

0.18

0.22

0.26

0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60

cc

• Range of test results divided into Range of test results divided into segments or segments or binsbins

• Range of test results divided into Range of test results divided into segments or segments or binsbins

Precision Weighted RankingPrecision Weighted RankingPrecision Weighted RankingPrecision Weighted Ranking

• Coders in subsequent intervals Coders in subsequent intervals score score bin numberbin number

• Coders in subsequent intervals Coders in subsequent intervals score score bin numberbin number

1 2 3 4 5 6 70.2238 0.4263 0.6357 0.8522 1.0762 1.3077 1.54720.4263 0.6357 0.8522 1.0762 1.3077 1.5472 1.7948

V7V8V6V9

V3V1

V4V5V2

Bin 1 Bin 3 Bin 4 Bin 5 Bin 7

• Coder scores are determined by Coder scores are determined by which bin their test result falls which bin their test result falls intointo

• Coder scores are determined by Coder scores are determined by which bin their test result falls which bin their test result falls intointo

Confidence interval of test

Confidence interval of test

• The resolution (or The resolution (or 95% 95% confidence interval) confidence interval) of the test of the test determines determines bin bin sizesize

• The resolution (or The resolution (or 95% 95% confidence interval) confidence interval) of the test of the test determines determines bin bin sizesize

• Worst coder always scores 1. In Worst coder always scores 1. In this test Vocoder 7 came lastthis test Vocoder 7 came last

• Worst coder always scores 1. In Worst coder always scores 1. In this test Vocoder 7 came lastthis test Vocoder 7 came last

• Scores for vocoders 6, 8 and 9 Scores for vocoders 6, 8 and 9 were 4 - 5 confidence intervals were 4 - 5 confidence intervals above that of V7. They all score 5above that of V7. They all score 5

• Scores for vocoders 6, 8 and 9 Scores for vocoders 6, 8 and 9 were 4 - 5 confidence intervals were 4 - 5 confidence intervals above that of V7. They all score 5above that of V7. They all score 5

Score = 1

Score = 7


Combined Performance IndexCombined Performance IndexCombined Performance IndexCombined Performance IndexCoder Wgt.

Performance

Characteristic

Wgt.Test

MethodWgt.

Type Conditio

nWgt.

Condition

Wgt.Cond. by

Type

Cond. by Type by

Char.

Cond. by Type by Char. by

2.4 Coder

Cond. by Type by Char. by

1.2 Coder

2400bps 60% Intelligibility 41.8% DRT(US) NA Baseline 27.4% Quiet 100.0% 27.4% 11.44% 6.86% 4.58%

1200bps 40% CVC(NL) NA TOTAL 100.0%Inteltrans(FR) NA Acoustic Noise56.8% SNR(12) 11.1% 6.3% 2.64% 1.58% 1.06%

SNR(6) 11.1% 6.3% 2.64% 1.58% 1.06%Office 11.1% 6.3% 2.64% 1.58% 1.06%MCE Field

Shelter11.1% 6.3% 2.64% 1.58% 1.06%

HMMMWV or P4

11.1% 6.3% 2.64% 1.58% 1.06%

M2A2 Bradley or

Leclerc11.1% 6.3% 2.64% 1.58% 1.06%

UH60 Black Hawk

11.1% 6.3% 2.64% 1.58% 1.06%

F15 or Mirage-

200011.1% 6.3% 2.64% 1.58% 1.06%

Volvo 11.1% 6.3% 2.64% 1.58% 1.06%TOTAL 100.0%

Transmission.

Channel7.4%

Random Bit Errors

(1%)100.0% 7.4% 3.08% 1.85% 1.23%

TOTAL 100.0%Tandem 8.4% CVSD=>Coder100.0% 8.4% 3.52% 2.11% 1.41%

TOTAL 100.0%

TOTAL 100.0% CHECK 800.0% 100.0% 41.80% 25.08% 16.72%

Whispered Speech2.2% SRT(NL) NA Special 100.0%Whispered Speech

100.0% 100.0% 2.20% 1.32% 0.88%

TOTAL 100.0%

TOTAL 100.0% CHECK 200.0% 100.0% 2.20% 1.32% 0.88%Quality 34.2% MOS(US) NA Baseline 42.1% Quiet 100.0% 42.1% 14.40% 8.64% 5.76%

MOS(NL) NA TOTAL 100.0%Acoustic Noise52.6% SNR(12) 14.0% 7.4% 2.52% 1.51% 1.01%

SNR(6) 10.0% 5.3% 1.80% 1.08% 0.72%Office 20.0% 10.5% 3.60% 2.16% 1.44%MCE Field

Shelter16.0% 8.4% 2.88% 1.73% 1.15%

HMMMWV

10.0% 5.3% 1.80% 1.08% 0.72%

F15 10.0% 5.3% 1.80% 1.08% 0.72%Volvo 20.0% 10.5% 3.60% 2.16% 1.44%

TOTAL 100.0%Tandem 5.3% CVSD=>Coder100.0% 5.3% 1.80% 1.08% 0.72%

TOTAL 100.0%

TOTAL 100.0% CHECK 600.0% 100.0% 34.20% 20.52% 13.68%

Quality BER 1.8% MOS(NL) NATransmis

sion. Channel

100.0%Transmis

sion. Channel

100.0% 100.0% 1.80% 1.08% 0.72%

TOTAL 100.0%

TOTAL 100.0% CHECK 200.0% 100.0% 1.80% 1.08% 0.72%


Phase 2 Combined Performance IndexPhase 2 Combined Performance IndexPhase 2 Combined Performance IndexPhase 2 Combined Performance Index

0

1

2

3

4

5

6

7

8

9

US

FR

TU

0

1

2

3

4

5

6

7

8

9

US

FR

TU

• Selection made on combined scores at 2400 and 1200 bps

• 60% - 2400 bps score

• 40% - 1200 bps score


Phase 2 Combined Performance IndexPhase 2 Combined Performance IndexPhase 2 Combined Performance IndexPhase 2 Combined Performance Index

0

1

2

3

4

5

6

7

8

9

10

0

1

2

3

4

5

6

7

8

9

10


Specific Results - Intelligibility Specific Results - Intelligibility Specific Results - Intelligibility Specific Results - Intelligibility

• Results of all Results of all coders in all noise coders in all noise conditions (CVC conditions (CVC test) test)

• Results of all Results of all coders in all noise coders in all noise conditions (CVC conditions (CVC test) test)



In

telli

gib

ility

sco

re (

%)

I

nte

llig

ibili

ty s

core

(%

)


Specific Results - Speech Quality Specific Results - Speech Quality Specific Results - Speech Quality Specific Results - Speech Quality

• Range of Mean Range of Mean Opinion Score test Opinion Score test • 1 (Bad) 1 (Bad) • 2 (Poor)2 (Poor)• 3 (Fair)3 (Fair)• 4 (Good)4 (Good)• 5 (Excellent)5 (Excellent)

• Results of all Results of all coders in all noise coders in all noise conditions (MOS conditions (MOS test) test)

• Range of Mean Range of Mean Opinion Score test Opinion Score test • 1 (Bad) 1 (Bad) • 2 (Poor)2 (Poor)• 3 (Fair)3 (Fair)• 4 (Good)4 (Good)• 5 (Excellent)5 (Excellent)

• Results of all Results of all coders in all noise coders in all noise conditions (MOS conditions (MOS test) test)



M

ea

n O

pin

ion

Sco

re

Me

an

Op

inio

n S

core


Specific Results - Language DependencySpecific Results - Language DependencySpecific Results - Language DependencySpecific Results - Language Dependency

French-English

R2 = 0.71

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

-1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0

French SRT (dB SNR)

En

gli

sh S

RT

(d

B S

NR

)• Language Language dependency of all dependency of all tested coderstested coders

• The closer a point The closer a point lies to the lies to the xx==yy diagonal, the less diagonal, the less language language dependant the dependant the voice codervoice coder

• Language Language dependency of all dependency of all tested coderstested coders

• The closer a point The closer a point lies to the lies to the xx==yy diagonal, the less diagonal, the less language language dependant the dependant the voice codervoice coder


Current positionCurrent positionCurrent positionCurrent position

• Phase 1Phase 1• CompletedCompleted• Results available in NC3A Technical Note-881Results available in NC3A Technical Note-881

• Phase 2Phase 2• All material processed and analysedAll material processed and analysed• Results collated Results collated • Results analysed and blind removed Results analysed and blind removed • Coder selected on 24 October 2001Coder selected on 24 October 2001

• Stanag 4591 knownStanag 4591 known•MELPeMELPe

• Phase 1Phase 1• CompletedCompleted• Results available in NC3A Technical Note-881Results available in NC3A Technical Note-881

• Phase 2Phase 2• All material processed and analysedAll material processed and analysed• Results collated Results collated • Results analysed and blind removed Results analysed and blind removed • Coder selected on 24 October 2001Coder selected on 24 October 2001

• Stanag 4591 knownStanag 4591 known•MELPeMELPe


NC3A - Current activityNC3A - Current activityNC3A - Current activityNC3A - Current activity

• Test Process Phase 3Test Process Phase 3• Real-time Implementation of Phase 2 winnerReal-time Implementation of Phase 2 winner• Communicability testsCommunicability tests

–real-life communication problemreal-life communication problem–end-to-end delay effectsend-to-end delay effects

• Assist in drafting STANAG 4591Assist in drafting STANAG 4591• Advise on the use and implementation of STANAG 4591Advise on the use and implementation of STANAG 4591

• Test Process Phase 3Test Process Phase 3• Real-time Implementation of Phase 2 winnerReal-time Implementation of Phase 2 winner• Communicability testsCommunicability tests

–real-life communication problemreal-life communication problem–end-to-end delay effectsend-to-end delay effects

• Assist in drafting STANAG 4591Assist in drafting STANAG 4591• Advise on the use and implementation of STANAG 4591Advise on the use and implementation of STANAG 4591


0

10

20

30

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50

60

70

80

CO

TS

X

CO

TS

Y

CO

TS

Z

ME

LP

e

CO

TS

X

CO

TS

Y

CO

TS

Z

ME

LP

e

6 dB SNR

12 dB SNR

Quiet

0

10

20

30

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50

60

70

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CO

TS

X

CO

TS

Y

CO

TS

Z

ME

LP

e

CO

TS

X

CO

TS

Y

CO

TS

Z

ME

LP

e

6 dB SNR

12 dB SNR

Quiet

Stanag 4591 vs COTS voice codersStanag 4591 vs COTS voice codersStanag 4591 vs COTS voice codersStanag 4591 vs COTS voice coders

Male speaker Female speaker

COTS X = 6 kbps

COTS Y = 4.56 kbps

COTS X = 4.56 kbps

MELPe = 2.4 kbps


ConclusionConclusionConclusionConclusion

• STANAG 4591 providesSTANAG 4591 provides

• substantially improved performancesubstantially improved performance– speech qualityspeech quality– intelligibilityintelligibility– noise immunity noise immunity

• reduced throughput requirementsreduced throughput requirements

• interoperabilityinteroperability

• STANAG 4591 providesSTANAG 4591 provides

• substantially improved performancesubstantially improved performance– speech qualityspeech quality– intelligibilityintelligibility– noise immunity noise immunity

• reduced throughput requirementsreduced throughput requirements

• interoperabilityinteroperability


Further informationFurther informationFurther informationFurther informationStanag 4591 test and selection processStreet MD, “Future NATO narrow band voice coder selection: Stanag 4591”, NC3A Technical Note 881, The Hague, December 2001

http://nc3a.info/Voice

Street MD and Collura JS, “Interoperable Voice Communications: test and selection of STANAG 4591”, RTA IST Symposium - NATO Research and Technology Agency (Information Systems and Technology panel) Tactical Military Communications symposium, Warsaw, October 2001

http://www.rta.nato.int/IST.htm

Street MD and Collura JS, “The test and selection of the future NATO narrow band voice coder”, RCMCIS - NATO Regional Conference on Military CIS, Warsaw, Zegrze, October 2001.

http://www.wil.waw.pl/ses3.htm

MELPe: the selected voice coderCollura JS and Rahikka DJ, “Interoperable secure voice communications in tactical systems, IEE coll. on Speech coding algorithms for radio channels, London, February 2000.

An overview of the MELP voice coder and its use in military environments http://www.iee.org/OnComms/pn/communications

Collura JS, Rahikka DJ, Fuja TE, Sridhara D and Fazel T, “Error coding strategies for MELP vocoder in wireless and ATM environments”, IEE coll. on Speech coding algorithms for radio channels, London, February 2000.

Performance of MELP with a variety of different error correction mechanismshttp://www.iee.org/OnComms/pn/communications


Information and Source Code available from:Information and Source Code available from:Information and Source Code available from:Information and Source Code available from:

http://elayne.nc3a.nato.int/S4591/http://elayne.nc3a.nato.int/S4591/

Applied Communication Technologies Branch

CIS Division

NATO C3 Agency

PO Box 174

2501 CD , The Hague

The Netherlands

Tel: +31 70 374 3043

Fax: +31 70 374 3049

Email: [email protected]

http://elayne.nc3a.nato.int/S4591/http://elayne.nc3a.nato.int/S4591/

Applied Communication Technologies Branch

CIS Division

NATO C3 Agency

PO Box 174

2501 CD , The Hague

The Netherlands

Tel: +31 70 374 3043

Fax: +31 70 374 3049

Email: [email protected]

NATO UNCLASSIFIED 1 [email protected] The NATO Post-2000 Narrow Band Voice Coder: Test and Selection...

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