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APIC Vocoder Task Group Overview

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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  1. APIC Vocoder Task Group Overview Project 25 Steering Committee Meeting Special Session April 25, 2008 Ernest Hofmeister, Chair Vocoder Task Group

  2. 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

  3. 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.

  4. 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

  5. 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

  6. 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)

  7. 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

  8. 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

  9. Vocoder Task Group • End-Quick Overview • Comments & Questions • Selected Voice Quality Test Results from Published Documents Follow for Those with Interest Thank-You

  10. 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.

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

  12. 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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