Assessment of Military VHF Radios used for ATC Voice Communications

Transcription

1 853d Electronic Systems Group Assessment of Military VHF Radios used for ATC Voice Communications This material has been cleared for public release by 66 ABW/PA (23 March / case # 66 ABW Distribution Statement A: Approved for public release; distribution is unlimited. Mr. Michael Bernock The MITRE Corporation 14 April 2010 Approved for Public Release: Distribution Unlimited

2 Overview Why assess? What are the civil requirements? Major artifacts Radio compliance overview Lessons Learned Closing Remarks Slide 2

3 Why Assess? Regulatory issues Control of RF emissions Protection from harmful interference Interoperability More to it than recent 8.33 khz GATM focus Offset carrier systems (25/8.33); tropo systems Cohabitation Civil/derivative platforms: TSO d hardware Military unique: self certification Other Focus on military functionality: tactical vs. civil Programmatic and logistical issues Slide 3

4 Civil Requirements: The Generic VHF Voice Matrix ICAO SARPS International Standards and Recommended Practices, Annex 10, Volume III, Part II, Voice Communication Systems TSO-C169 VHF Radio Communications Transceiver Equipment Operating Within the Radio Frequency Range MHz RTCA DO-186 Minimum Operational Performance Standards for Airborne Radio Communications Equipment Operating Within the Radio Frequency Range MHz Eurocae ED-23 Minimum Performance Specification for Airborne VHF Receiver Transmitter Operating in the Frequency Range MHz Slide 4

5 Overview of Major Artifacts Box Level Performance Bench Test Report; JITC test program EMI/EMC Test Report Environmental Test Report DD Form 1494 (J/F-12) Installed System Performance Compatibility with platform power/environment Compatibility with other avionics (EMI/EMC, hazard analysis) Ground/Flight Test Report (contractor/gov t) Control/display operation, visibility, and access Communications range testing (AC 25-7A) Slide 5

6 Flight Testing: AC 25-7A Transmitter Class 3: 25 khz, 200 mile 4: 25 khz, 100 mile * 5: 8.33 khz, 200 mile 6: 8.33 khz, 100 mile * (*) Operational Altitude threshold: 18k Long Range Test High Angle Test Approach Slide 6

7 Table Key Compliance (with civil standards) Green = 100% compliant, no exceptions Yellow = Minor compliance shortfall(s) Red = Major compliance shortfall(s) [Does not perform intended function] Risk (of operational impact) Green = None expected Yellow = Moderate risk, mitigate by operational work around Red = High risk, must resolve Slide 7

8 VHF Voice Radio Summary (Box level compliance) Compliance Compliance Compliance Compliance Compliance Compliance Compliance Compliance Compliance Risk Risk Risk Risk Risk Risk Risk Risk Risk Complete «RTA-44D (TSO, in catalog) «RT-1851A/ARC-210 «RT-1851/ARC-210 (in catalog) «RT-1818/ARC-232 (Exportable) «RT-1794/ARC-210 «RT-1747/ARC-210 «RT-1808A/ARC-231 «RT-1826/ARC-234, AITG «RT-1704/ARC-222 ACC/AFSOC C-130s In process MXF-626K (ARC-222 replacement) Slide 8

9 Evolving Civil Requirements RTCA DO-186B now current Incorporates Changes 1&2: GNSS band emissions and administrative cleanup Incorporates 25 khz offset/multi-carrier squelch requirement from TSO-C169 No new requirements developed Eurocae ED-23C is in the wings No word yet on implementation mandate Introduces 8.33 khz offset/multi-carrier receivers (G1/G2) Steeper roll-off above Rx audio passband Improved squelch operation in offset/multi-carrier environment NextGen/Single European Sky Focus is on augmenting voice with data link 25k and 8.33k analog voice systems are still in the plan Slide 9

10 Lessons Learned Box Level Issues Transmitter emissions & modulation spectrum Receiver susceptibility to interference Offset carrier systems & CLIMAX squelch DO-176 & FM immunity Installed Performance Issues Control & display: Discrete vs. integrated [Hazard analysis drives discrete control requirement; major or DO-178 level C] 8.33 channel display and operator training Platform environment and power Communications range, Antenna choice Performance in the field More feedback on operational performance is needed Closed loop system refines process, improves assessment integrity Slide 10

11 25 khz vs khz Modes and Offset Carrier Systems Slide 11

12 Info on 8.33 khz Operation Channel Tx/Rx Mode khz khz khz khz khz khz Slide 12

13 Standard 25 khz System Slide 13

14 Standard 25 khz System Frequency Stability Slide 14

15 Standard 25 khz System BRAVO Center ABLE Center BRAVO Center ZULU Center Slide 15

16 Standard 25 khz System BRAVO Center ABLE Center BRAVO Center ZULU Center Slide 16

17 Standard 25 khz System BRAVO Center ABLE Center BRAVO Center ZULU Center Only one desired signal in receiver passband Geographic separation aids spectrum management Limit aircraft transmit power Slide 17

18 8.33 khz Channelized System 25 khz spacing Slide 18

19 8.33 khz Channelized System Add the channels Slide 19

20 8.33 khz Channelized System Tighten up the spectrum Slide 20

21 8.33 khz Channelized System Typical 25 khz receiver response Slide 21

22 8.33 khz Channelized System Reduce receiver bandwidth to match spectral mask Slide 22

23 Review Class C receiver Class 3/4 transmitter Class E receiver Class 5/6 transmitter Slide 23

24 25 khz Receiver Tuning on 8.33 khz Channels Slide 24

25 25 khz Receiver Tuning on 8.33 khz Channels Receiver bandwidth too wide Slide 25

26 25 khz Transmitter in 8.33 khz Channelized System Compatible; slight loss of information but Slide 26

27 25 khz Transmitter in 8.33 khz Channelized System Adjacent channel splatter No ability to transmit on intermediate channels Slide 27

28 8.33 khz transmitter in 25 khz Channelized System Compatible; 8.33 radios typically transmit same signal in both modes Slide 28

29 8.33 khz Receiver in 25 khz Channelized System Compatible; tunes all the 25 khz channels Looks acceptable, but Slide 29

30 Offset Carrier System Start here with 25 khz spacing Slide 30

31 Offset Carrier System Rely on 25 khz legacy radio receiver bandwidth Slide 31

32 Offset Carrier System Simulcast on offset carriers on ground to extend communications range Aircraft receiver frequency does not change Slide 32

33 Offset Carrier System BANJO Center F3 F2 F1 F1 F2 F Slide 33

34 Offset Carrier System BANJO Center F3 F2 F1 F1 F2 F Slide 34

35 Offset Carrier System BANJO Center F3 F2 F1 F1 F2 F Slide 35

36 Offset Carrier System BANJO Center F3 F2 F1 F1 F2 F Dual mode radios must provide a wide receiver response in 25 khz mode and a narrow response in 8.33 khz mode Receiver squelch systems must perform properly when multiple carriers are present in receiver pass band Slide 36

37 Finally, a quick mention of Beyond Line-of-Sight VHF Relies on atmospheric ducting High ERP transmitters: 25 kw Multiple receivers supporting diversity reception Deployed worldwide VHF Extended Range Network (VERN); Gulf/Caribbean Iceland and Greenland Oceanic China Relies on a MOPS compliant radio in aircraft Slide 37

38 Military Radios for VHF ATC Summary MOPS Compliance is important Insures compatibility with the ground systems Minimizes unwanted RF you generate Minimizes off channel interference that will affect you It s not just about the box System must perform once installed Power, environment, antenna, HMI Ground system technologies vary Straight 25 k and 8.33 k systems Offset carrier Beyond line-of-sight, tropo There are some low risk military radio choices Best Equipped, Best Served! Slide 38

39 Closing Remarks THANK YOU FOR YOUR ATTENTION Questions? Mike Bernock (781) Slide 39