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APIC Vocoder Task Group Overview. Project 25 Steering Committee Meeting Special Session April 25, 2008 Ernest Hofmeister, Chair Vocoder Task Group. TIA. Project 25/34 Steering Committee. APIC. Private Radio Section. TR8. Project 25/34 Steering Committee Subgroups

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APIC Vocoder Task Group Overview

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Apic vocoder task group overview l.jpg

APIC Vocoder Task Group Overview

Project 25 Steering Committee Meeting

Special Session

April 25, 2008

Ernest Hofmeister, Chair Vocoder Task Group


Vocoder task group and tr 8 4 vocoder subcmte location in tia tr 8 p25 structure l.jpg

TIA

Project 25/34 Steering Committee

APIC

Private Radio Section

TR8

Project 25/34 Steering Committee Subgroups

(e.g., P25 & P34 User Needs Subcommittees)

APIC

Subgroups

(e.g., Task Groups, Working Groups)

TIA TR-8 Subgroups

(e.g., Subcommittees)

Vocoder Task Group (and TR-8.4 Vocoder subcmte) Location in TIA TR-8 & P25 Structure

TR-8.4 Vocoder subcmte

Vocoder Task Group


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Early Vocoder Work ~1991-1999

  • Project 25 RFP and Proposals for Low Rate Vocoder

  • Mean Opinion Score (MOS) Tests and Evaluation

  • Selection of DVSI IMBE Vocoder (now Baseline Full Rate)

  • TIA Standardization

    • ANSI/TIA/EIA 102.BABA, Project 25 Vocoder Description, May 1998.

    • ANSI/TIA/EIA 102.BABB, Project 25 Vocoder Mean Opinion Score Conformance Test, May 1999.

    • ANSI/TIA/EIA 102.BABC, Project 25 Vocoder Reference Test, April 1999.


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DVSI Vocoder Evaluation Results

Original P25 IMBE @ 4.4 kbps--MOS ~ 3.4

Recent Voice Quality vs Bit Rate

Source: DVSI Website

Excerpt Com-Net Ericsson Contribution, Hofmeister, TR-8.12, Mesa, Jan 2001


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Recent Vocoder Work 2003-2008 (1)

  • P25 Vocoder for P25 Phase 2 TDMA

  • DAQ vs BER Information for TIA TR-8.18, TSB-88

  • Cognizant of Technical Work and Relevant Technical Contributions Related to IAFC Digital Working Group


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Recent Vocoder Work 2003-2008 (2)

  • P25 Vocoder for P25 Phase 2 TDMA

    • MOS (Mean Opinion Score) Voice Quality Testing—03-05

      • DVSI Original Baseline Full Rate IMBE(BFR), Enhanced Full Rate (EFR), and Enhanced Half-Rate (EHR)

      • Experiment 1 – MOS vs Radio Channel Models

      • Experiment 2 – MOS vs Selected Moderate Background Noise

      • Exp 1 & 2 Results Published in TIA TSB-102.BABE

      • Experiment 3 – ITS MOS vs Selected High Background Noises

      • Ex 3 Results Published in TIA TSB-102.BABF

    • Enhanced DVSI Half-Rate Vocoder Recommended to P25 Steering Committee for P25 Ph 2 TDMA as Part of Dual-Rate Vocoder—Jan 2006 (re-affirmed Jan 2007)


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Recent Vocoder Work 2003-2008 (3)

  • P25 Vocoder for P25 Phase 2 TDMA--cont

    • (P25 Steering Committee Adopted Recommendation – April 2007)

    • (P25 Steering Committee Adopted Enhanced DVSI Full-Rate Vocoder as New Baseline for P25 Phase 1 Going Forward – Oct 2005 (re-affirmed Jan 2008))

    • P25 Vocoder Standardization Regarding Enhanced Capability

      • First “Prong”--Developing P25 Half-Rate Vocoder Annex (Interoperability) Standard to Compliment Existing Vocoder Stnds

        • Comment Resolution Completed and Accepted by VTG

      • Second “Prong”--Developing Audio, Quality Rqmt & Verif Test

        • Voice Quality Performance Requirement to Assure Performance Statistically Equivalent to or Better than the Enhanced Vocoder Performance Documented in TSB-102.BABE

        • Test Method to Assure Compliance to Voice Quality Performance Requirement


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Recent Vocoder Work 2003-2008 (4)

  • DAQ vs BER Information for TIA TR-8.18, TSB-88

    • DAQ - Delivered Audio Quality

    • BER – Bit Error Rate

    • For TSB-88 Wireless Systems Compatibility Reference Book

    • Receiving and Working Technical Contributions

  • Cognizant of Technical Work and Relevant Technical Contributions Related to IAFC Digital Working Group

    • TR-8 Focal Point within TIA/P25 Community

    • Institute of Telecommunication Sciences (ITS) Work


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Vocoder Task Group

  • End-Quick Overview

  • Comments & Questions

  • Selected Voice Quality Test Results from Published Documents Follow for Those with Interest

Thank-You


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Experiment 1 Results – Fig 9-1 TSB-102.BABE

  • MOS Test 2003 and 2004, TSB-102.BABE

    • Measured audio quality of enhanced vocoders in two experiments.

    • 5 channel conditions:1mph(1%), 5mph(1% & 3%), 60mph (3% & 5%)Soft decision C4FM channel

    • Clean condition

    • 3 noise conditions: Car (10dB SNR), Babble (15dB SNR), Street (10dB SNR), noise spectrum is known

    • Database was 32 sentence pairs from Conformance, TIA-10.BABB.


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Experiment 2 Results – Fig 9-2 TSB-102.BABE


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Experiment 3 Results – From Fig 9-1 TSB-102.BABF

  • MOS Test 2005, TSB-102.BABF

    • Clean condition

    • 8 noise conditions: 3 fire truck, 2 boat, 2 helicopter, 1 police car

      • SNR and noise spectrum is known

    • Database was 40 sentence pairs recorded by ITS


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