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Air Traffic Systems

Air Traffic Systems. Air Traffic Systems. SECONDARY SURVEILLANCE RADAR. INTRODUCTION AND BASIC PRINCIPLES. Transmitter Pulses. RX & PROCESSING. TX. Received Signal. Timing & Control. Radar Picture. Basic Primary Radar. DISADVANTAGES OF PRIMARY RADAR. High Power Clutter

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Air Traffic Systems

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  1. Air Traffic Systems

  2. Air Traffic Systems SECONDARY SURVEILLANCE RADAR INTRODUCTION AND BASIC PRINCIPLES

  3. Transmitter Pulses RX & PROCESSING TX Received Signal Timing & Control Radar Picture Basic Primary Radar

  4. DISADVANTAGES OF PRIMARY RADAR • High Power • Clutter Permanent Echo's Weather i.e. Rain etc. • Identification

  5. Basic Secondary Radar Tx 1030 MHz SSR RX & PROCESSING TX Secondary returns Timing & Control Radar Picture 123 ABC Decoder Rx 1090 MHz

  6. Modes and Pulse Spacing 3µs Military A/C Ident - Mode 1 5 µs Military Mission Ident - Mode 2 8 µs Joint Military & Civil A/C Ident - Mode 3/A 17 µs Civil A/C Ident - Mode B 21 µs Altitude Data - Mode C

  7. SSR Questions (Modes) Who are you ? (Mode 1 and 3/A) What is your altitude ? (Mode C) What is your mission number ? (Mode 2) Are you FRIEND or FOE ? (Mode 4)

  8. Mode Interlacing The ability of the system to automatically change modes. This enables more diverse information to be gathered.

  9. Military transponder set to :- Civil transponder set to :- Mode 1, code = 1100 Mode 3/A, code = 2210 Mode 3/A, code = 4170 h1 h2 Mode C, code = h2 Mode C, code = h1 C 3/A C 3/A C 1 1 3/A 1 Civil No 2210 h2 No 2210 h2 No 2210 h2 Coded Replies h1 1100 Military 1100 4170 1100 4170 h1 4170 h1 MODE INTERLACING Mode interlace pattern 1, 3A, C

  10. EMERGENCY REPLIES CIVILIAN EMERGENCY GENERAL EMERGENCY - 7700 RADIO FAILURE - 7600 HI-JACK - 7500

  11. ADVANTAGES OF SSROVER PRIMARY RADAR • POSITIVE IDENTIFICATION • CLUTTER ELIMINATION • LOWER POWER FOR EQUIVALENT RANGE • ACCURATE HEIGHT INFORMATION • EMERGENCY INFORMATION

  12. DISADVANTAGES OF SSR INTERROGATIONS VIA SIDE LOBES FALSE REPLIES UNCORRELATED IN TIME (FRUIT) GARBLING TRACK WANDER

  13. Aircraft A 80 miles Aircraft 200 Miles C Aircraft B

  14. Aircraft C P2 P1 P3 2 s  INTERROGATION SIDE LOBE SUPPRESSION Aircraft A 80 miles 200 Miles Aircraft B

  15. Site B unwanted replies PRF 260Hz Interrogation Site A PRF 250Hz F.R.U.I.T.

  16. reply Correct (Frame pulses + 2 information..) FRUIT Second PRP Replies First PRP Replies Coincidence 1 PRF DELAY Gate De-fruited video O/P DEFRUITER PRINCIPLE

  17. Overlapping OVERLAPPING replies A4 B2 D2 D4 F2 End of Beginning of pulse pulse train train from from aircraft A aircraft B F1 A2 C2 C4 GARBLE

  18. TRACK WANDER 1st sweep 2nd sweep 3rd sweep 4th sweep

  19. TRACK WANDER 1st sweep 2nd sweep sweep sweep track

  20. THE MONOPULSE SYSTEM ELIMINATES TRACK WANDER BECAUSE ONLY ONE PULSE FROM A REPLY TRAIN IS NEEDED TO OBTAIN AN ACCURATE BEARING.

  21. COMBINED SUM & DIFFERENCE PATTERNS BORE SIGHT

  22. Mono-pulse Secondary Surveillance Radar MSSR

  23. Cardion Secondary Surveillance Radar Antenna mounted on Tactical Watchman Mounted on T101 Air Defence Radar

  24. AIR TRAFFIC CONTROL SSR SYSTEM APPLICATIONS MILITARY AIRCRAFT CIVIL AIRCRAFT MARITIME AIRCRAFT MISSILE NAVAL SYSTEMS

  25. MODE S I am able to reply to your “ALL CALL” because I have Mode S 0.5 s This is my discrete address Data block 56 s or 112 s Preamble 8.0 s Bit 1 Bit 2 Bit 3 Bit 4 Bit N 1 1 0 1 0 1 0 0 1 0 0.5 s

  26. The future of SSR • Mode S – becoming compulsory under EASA rules • CSSR and MSSR don’t support Mode S

  27. Airfield layout

  28. Any Questions ?

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