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Aviation Use of Radar

Aviation Use of Radar. WP8B/8D Radar Seminar September 2005. Radar Types. Ground-based Surveillance Long Range Terminal Others Precision approach Surface detection Weather Airborne Radar altimeter Weather. Ground: Surveillance Radar (1 of 2). Long Range Radar ~ 130 sites in US

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Aviation Use of Radar

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  1. Aviation Use of Radar WP8B/8D Radar Seminar September 2005

  2. Radar Types • Ground-based • Surveillance • Long Range • Terminal • Others • Precision approach • Surface detection • Weather • Airborne • Radar altimeter • Weather WP8B/8D Radar Seminar - Aviation

  3. Ground: Surveillance Radar (1 of 2) • Long Range Radar ~ 130 sites in US • Band: 1240-1370 MHz, in ARNS (5.331, 5.334) • Sensitivity: 1-2 m2 target @ 200 to 250 nmi • Mission: Detection and tracking of aircraft at long ranges for ATC use. • Secondary weather detection function • Backup for terminal radar (w/ increased separations) • 12 second scan • Vertical polarization for tracking; circular for weather • Shared with Defense Department and Department of Homeland Security WP8B/8D Radar Seminar - Aviation

  4. Ground: Surveillance Radar (2 of 2) • Terminal Radar ~ 300 sites in US • Terminal area coverage • 4.8 second scan • Normally sited at airports with traffic above a certain level • Some are “mosaiced” allowing multiple radars to form a single picture of the airspace • Integral part of “procedural” response to navigation aid outages WP8B/8D Radar Seminar - Aviation

  5. Ground: Others (1 of 2) • Precision Approach Radar (PAR) • Band: 9.0-9.2 GHz • Allows controller to direct precision approaches • Primarily military use in the US; civil back-up • Surface Detection • Band: 9.0-9.2 GHz (ASDE-X), 15.7-16.2 GHz (ASDE-3) • ASDE-X for small/medium airports; currently 30 systems, however expected to increase • ASDE-3 installed at 40 large airports • 1 second scan WP8B/8D Radar Seminar - Aviation

  6. Ground: Others (2 of 2) • Weather • NEXRAD ~ 150 sites in US • Band: 2700-3000 MHz • 200 nmi coverage volume • Sited off-airport • Series of scans in increasing altitudes, 6 minute repeat period • Single frequency, circular polarization • Terminal Doppler Weather Radar (TDWR) ~ 45 in US • Band: 5600-5650 MHz • Detects wind shear and local weather phenomena • 45 nmi coverage • Located at major airports with history of severe thunderstorms • Single frequency, multiple waveforms, multiple scan options depending on local conditions. WP8B/8D Radar Seminar - Aviation

  7. Airborne Radar • Radar altimeter • Band: 4200-4400 MHz in ARNS • Integral part of precision landing systems • Also integrated into terrain-warning sensors • Weather Radars • Bands: 5350-5470 MHz, 8750-8850 MHz, 9.3-9.5 GHz, 13.25-13.4 GHz • Used for weather detection, windshear and turbulence detection and ground mapping WP8B/8D Radar Seminar - Aviation

  8. Radar Hardware Characteristics • Ground-based Surveillance • Two frequency, paired with fixed delta-f (limits assignable channels) • Diplexed for increased performance, or hot-standby (use alternate frequency if interference detected) • Some use of chirped or compressed waveforms • Fan beams; newer versions with beam forming array to help provide target altitude discrimination • Sector blanking not allowed on commissioned radar, 360 degree coverage required • Ground-based Other • PAR/ASDE-X implement 4 frequencies, however can meet performance objectives with 2. • ASDE-3 has 16-frequency hopset, 2 assignable hopping patterns. • Multipath and rain attenuation offer significant challenges. • Weather radar is generally single frequency with multiple waveforms • Waveform selection tailored to prevailing weather patterns. • Sector scans can be implemented to focus attention on developing problem areas. WP8B/8D Radar Seminar - Aviation

  9. Airborne Radar Characteristics • Radar Altimeters • Frequency Range 4200-4400 MHz • Center Frequency 4300 +/- 25 MHz • Transmit power: 20 mW to 500 mW • Range: up to 1526 Meters • Pulse width 200 ns • Antenna Beamwidth 70 degrees WP8B/8D Radar Seminar - Aviation

  10. Airborne Radar Characteristics • Airborne Weather Radars • Band: 9300-9500 MHz • Avoidance Range 340 nm • Transmit Power to Antenna: 35 W – 12 kW • Pulse Width (microseconds): 1 to 28.8 • Antenna Pattern type – pencil beam • Antenna – flat plate and flat plate slotted array WP8B/8D Radar Seminar - Aviation

  11. Radar Processing Characteristics • Radar design depends on operational environment and performance goals. Some offer some form of screen clutter removal • Does not mitigate interference, simply keeps it from showing on the controller’s screen • Ground clutter mapping: If certain range bins keep getting reflections from a fixed target (e.g., a building), will notch-out those bins. • Moving Target processing: Will not show targets moving slower than a set threshold rate WP8B/8D Radar Seminar - Aviation

  12. Automatic Dependant Surveillance (ADS) • Aircraft periodically provides own-ship position and intent information (broadcast or on a contract basis) • Some question if ADS reduces need for radar • Issues: • Requires all aircraft to be equipped • Reduces possibility of “procedural workarounds” for navaid outages • Requires all aircraft to participate • How address a 9/11-like situation? • Bottom line: Many issues need to be addressed, studies continue. WP8B/8D Radar Seminar - Aviation

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