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VDL-3. It’s All About Data. ATN 2001 London, England Jim Williams Federal Aviation Administration September 19, 2001. VHF Spectrum Depletion. US Frequency Congestion Implications. Spectrum Depletion and System Capacity . 15 aircraft delayed for 5-10 minutes
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VDL-3 It’s All About Data ATN 2001 London, England Jim Williams Federal Aviation Administration September 19, 2001
Spectrum Depletion and System Capacity • 15 aircraft delayed for 5-10 minutes • Causes delays to 250 aircraft in only 20 minutes • Economic impact • Airlines • Secondary industries • National Economy • Something must be done!
Options for Next Generation Voice Communications • VHF Data Link Mode 3 • Subdivide to 8.33kHz Spacing • Other Technologies • Standards Development • Stringent Requirements • Maturity of Technology
Need for ATC Data Communications • Why ATC Data Communications? • National Airspace System Concept of Operations • FAA NAS Operational Evolution Plan • Why Aeronautical Telecommunications Network? • Standards and Recommended Practices • Network management • Information security
Options for Next Generation ATC Data Communications • Investigated options: ACARS, VDL-2, VDL-3, VDL-4, Satcom, HF Data link, other sub-networks • Subnetwork Issues • RF Co-site Interference issues • Architecture issues • Latency • Costs • Capacity • Conclusion • Both RTCA and ICAO selected VDL Mode 3 • VDL-2 approved for early implementation
RTCA initiated SC-172 to develop solution; VDL MASP started RTCA & ICAO recommended future A/G communication system be TDMA VDL-3 FAA/MITRE VDL-3 radio prototype tested ICAO/JCAB/ EuroControl/UK/ FRG/FAA complete VDL-3 SARPs validation 1991 1994 1997 1999 1990 1993 1995 1998 2000 ICAO AMCP recommends approval of VDL-3 DOT/FAA approved the Mission Needs Statement for NEXCOM ICAO identified VHF congestion problem RTCA/AEEC selected 31.5 kbps, D8PSK for VDL2/3 Investment Analysis completed, VDL-3 selected as FAA solution FAA JRC approves new NEXCOM VDL-3 Program Baseline COM/OPS/DIV ICAO Meeting approved VDL-3 for future communications VDL History
What is VDL-3? Frequency range 118–137 MHz Channelization 25 kHz centers Channel structure Same frequency for uplink and downlink Radio range 200 nmi for 4 channel capability (3 channels for greater ranges) Symbol rate 10.5 kbaud (3 bits /symbol) Modulation Differential 8-ary Phase Shift Keying (D8PSK) Access technique (MAC) Time Division Multiple Access (TDMA) Voice 4.8 kbps encoding (vocoder) Data Functionally simultaneous with voice
VDL-3 Channel Structure • 120 ms “TDMA frame” is the fundamental timing framework • Each slot contains two independent “subchannels”
Efficiency Flexibility FAA NEXCOM • VDL-3 is FAA’s approach to support both voice & data communications • Strategy • current technology • provide increased efficiency and flexibility • lower life cycle costs Up to 4 Times Current Voice Capacity Provides 4 Voice and/or Data Channels/ 25KHz Channel Current Voice Capacity 1 Voice Channel/25KHz Channel 1 Voice or Data Voice 2 Voice or Data 3 Voice or Data NEXCOM 4 Voice or Data 120.10 120.10 "120.10“ "120.101" "120.102" "120.103" "120.104"
Dem/Val NEXCOM“Transition to Digital Communications” 5-10 years Next 5 years 10-15 years 15-20 years Enroute High Airspace VDL-3Link 0101010100110010101 0101010100110010101 0101010100110010101 01010101001 VDL-2 Datalink 0101 01010101001 RCAG 10011001011010101 Analog Voice ARTCC 01010 AFSS National Airspace Terminal Airspace • Analog Voice, 25 KHz • Initial Datalink (VDL-2) • Full Operational Evaluation& Exercise of Digital Voiceand Datalink (VDL-3) • Maintain Terminal Analog Voice • Implement VDL-3Digital Voice • Expand Datalink VDL-2Applications • Expand EnrouteDigital Voice (VDL-3) • Initiate TerminalDigital Voice (VDL-3) • Increase Datalink Capacity& Capability (VDL-2 & VDL-3) • Expand Digital Voice (VDL-3) to all domains • Expand Datalink Capacityin all domainsand all applications(VDL-2 & VDL-3)
Why VHF Digital Link Mode 3? • Meets US Voice Capacity for ~30 years. • Meets the ICAO requirements for high reliability and low latency. • Provides for Voice and Data. The future of ATC is all aboutdata communications.