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

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Presentation on theme: "Air Traffic Systems. SECONDARY SURVEILLANCE RADAR INTRODUCTION AND BASIC PRINCIPLES Air Traffic Systems."— Presentation transcript:

1 Air Traffic Systems

2 SECONDARY SURVEILLANCE RADAR INTRODUCTION AND BASIC PRINCIPLES Air Traffic Systems

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

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

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

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

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 :- Mode 1, code = 1100 Mode 3/A, code = 4170 Mode C, code = h1 Civil transponder set to :- Mode 3/A, code = 2210 Mode C, code = h2 Military Civil No2210h2No2210h2No2210h h h h1 Coded Replies 1 3/A C 1 C 1 C Mode interlace pattern 1, 3A, C MODE INTERLACING h1 h2

10 EMERGENCY REPLIES CIVILIAN EMERGENCY GENERAL EMERGENCY RADIO FAILURE HI-JACK

11 ADVANTAGES OF SSR OVER PRIMARY RADAR  POSITIVE IDENTIFICATION  CLUTTER ELIMINATION  LOWER POWER FOR EQUIVALENT RANGE  ACCURATE HEIGHT INFORMATION  EMERGENCY INFORMATION

12 DISADVANTAGES OF SSR INTERROGATIONS VIA SIDE LOBES F ALSE R EPLIES U NCORRELATED I N T IME (FRUIT) GARBLING TRACK WANDER

13 200 Miles 80 miles Aircraft A C B

14 200 Miles 80 miles Aircraft A B P1P2 P3 2 s  INTERROGATION SIDE LOBE SUPPRESSION Aircraft C

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

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

17 GARBLE A4B2D2D4F2 A2 C2C4 F1 End of pulse train from aircraft A Beginning of pulse train from aircraft B Overlapping replies OVERLAPPING

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

19 TRACK WANDER 1st sweep 2nd 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 BORE SIGHT COMBINED SUM & DIFFERENCE PATTERNS

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 CIVIL AIRCRAFT MILITARY AIRCRAFT MARITIME AIRCRAFT NAVAL SYSTEMS MISSILE SSR SYSTEM APPLICATIONS

25

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

27 The future of SSR §Mode S – becoming compulsory under EASA rules §CSSR and MSSR don’t support Mode S

28 Airfield layout

29 Any Questions ?


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