modern architectures for radiolocation radars abraham van den berg geneva september 24 th 2005
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Modern Architectures for Radiolocation Radars Abraham van den Berg Geneva, September 24 th 2005. Agenda. Frequency sharing in Radiolocation bands Operational System Requirements Radar Modes and Architectures. Frequency sharing in Radiolocation bands. TELEMETRY. RLANs. GPS. IMT-2000.

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modern architectures for radiolocation radars abraham van den berg geneva september 24 th 2005

Modern Architectures for Radiolocation RadarsAbraham van den BergGeneva, September 24th 2005

Air Systems Division

agenda
Agenda
  • Frequency sharing in Radiolocation bands
  • Operational System Requirements
  • Radar Modes and Architectures

Air Systems Division

frequency sharing in radiolocation bands4
TELEMETRY

RLANs

GPS

IMT-2000

ENG/OB

WAS

Frequency Sharing in Radiolocation Bands
  • L-band: (1215 – 1400 MHz) RNSS:GPS, Glonass, Galileo
  • S-band: (2700 – 3600 MHz) MS:ENG/OB,Future IMT-2000
  • Aeronautical Telemetry
  • C-band: (5250 – 5850 MHz) MS: WAS, RLANs

Air Systems Division

operational system requirements6
Operational System Requirements
  • Operational System Requirements
    • Mission statements and requirements for a clear environment
    • Requirements for an EM polluted environment
    • Future radar requirements.

Air Systems Division

l band requirements 1
L-band Requirements (1)
  • Mission: Long Range Air Defence
  • Long range detection of conventional aircraft (RCS > 2 m2)
  • Medium range detection of latest generation ‘stealth’ air targets, i.e. missiles (RCS < 0.1 m2)
  • High performance w.r.t. Electronic Counter-Counter Measures
  • Guidance support for patrol aircraft
  • Surface surveillance up to the radar horizon.

Air Systems Division

l band requirements 2
L-band Requirements (2)
  • Mission: Volume Search by means of Multibeam Surveillance
  • Fast 3D scanning with gapless elevation coverage up to 70º
  • Excellent angular accuracy in elevation (< 1º)
  • Improved detection at low elevation (reduction of multipath effect)
  • Increased resistance against jamming and other interferences
  • Jamming detection
  • Improved operation in bad weather conditions
  • Suppression of sea and land clutter
  • Improved surface surveillance.

Air Systems Division

l band requirements 3
L-band Requirements (3)

An example of a naval Volume Search Radar

Air Systems Division

l band requirements 4
L-band Requirements (4)
  • L-band Requirements, highlights
  • Increasing number of spot frequencies in agile mode (Interoperability, Multipath)
  • Increasing system bandwidth (Detection of stealth targets, Multipath, ECM)
  • Digital beamforming for 3D scanning radars
  • Frequency diversity for ATC.

Air Systems Division

s band requirements 1
S-band Requirements (1)
  • Mission: Military Air Traffic Control
  • Civil ATC Radar modified for military application, i.e. with additional environmental constraints
  • Capability of countering chaff, deception and noise jamming.
  • Mission: Battlefield and Border Surveillance
  • 2D Detection and tracking of moving targets over a local area
  • Required to rapidly alert a co-located tracking sensor
  • Detection in land and weather clutter
  • Air and surface targets.

Air Systems Division

s band requirements 2
S-band Requirements (2)
  • Mission: Naval Surveillance
  • Two-dimensional
    • 2D primary surveillance and target indication
    • Air as well as surface targets
    • Suppression of sea clutter.
  • Three-dimensional (3D Single Beam)
    • Additional facility of measuring target altitude.
  • Three-dimensional (3D Multi-beam)
    • Multiple simultaneous beams to shorten reaction time.

Air Systems Division

s band requirements 3
S-band Requirements (3)
  • Mission: Naval Multifunction Radar
  • Surveillance and tracking in angle, range and velocity of multiple targets
  • Phased array technology (Active as well as passive)
  • Own missile guidance
  • Kill assessment.
  • Mission: Airborne Early Warning
  • Long range and very long range (BTH) surveillance
  • Target altitude determination
  • All weather operation.

Air Systems Division

s band requirements 4
S-band Requirements (4)

An example of a naval Multifunction Radar

Air Systems Division

s band requirements 5
S-band Requirements (5)
  • S-band Requirements, highlights
  • Increasing pulse bandwidth (Higher range resolution, NCTR)
  • Trend toward higher duty cycles
  • Increasing number of spot frequencies in agile mode (Interoperability, Multipath)
  • Increasing system bandwidth (Detection of stealth targets, Multipath, ECM)
  • Frequency diversity, up to 4 frequencies (ATC).

Air Systems Division

c band requirements 1
C-band Requirements (1)
  • Mission: Naval Surveillance (2D and 3D)
  • Same as in S-band, but with shorter range, 30 km - 120 km.
  • Mission: Instrumentation Tracking
  • On test ranges: Very accurate tracking of space and aeronautic vehicles undergoing developmental and operational testing
  • Large parabolic reflector antennas and high EIRP
  • Autotracking antennas, either on the skin echo or on a beacon.

Air Systems Division

c band requirements 2
C-band Requirements (2)
  • Mission: Battlefield Weapon Locator
  • Required to locate position of enemy fire and impact location
  • Rapid horizontal scan in search mode
  • Rapid horizontal and vertical scan in tracking mode
  • Very agile, both in frequency and beam position
  • Extremely sensitive, due to targets with very small RCS.

Air Systems Division

c band requirements 3
C-band Requirements (3)
  • C-band Requirements, highlights
  • Frequency agility over a wide system bandwidth
  • Pulse bandwidth increases for high range resolution needs
  • More and more 3D radars with fast beam agility
  • Commonalitie with S-band radars, usually with shorter range
  • Specificity: Very sensitive long range instrumentation radar.

Air Systems Division

requirements in an em polluted environment
Requirements in an EM Polluted Environment
  • Inter-system electromagnetic compatibility
  • Essentially compatibility with other radars in the same band
  • No known requirements to share with communication systems
    • Most of the time radars are protected by a primary status
    • When co-primary, other systems are required to avoid harmful interference to radars.
  • Electronic protection (or ECCM) requirements
  • Chaff, noise jamming, false target generation, deception
  • These requirements include:
    • Frequency hopping and automatic tuning
    • Advanced antenna design, combined with advanced signal and data processing.

Air Systems Division

future requirements 1
Future Requirements (1)
  • Tactical Ballistic Missile Defence (TBMD)
  • Detection and tracking of ballistic missiles
  • Cueing of other sensors
  • Will require a mix of sensors at different frequencies.

Air Systems Division

future requirements 2
Future Requirements (2)
  • Low Probability of Intercept (LPI)
  • No detection from ESM, jammer receivers, ARM receivers (even with a sensitity better than –80 dBm
  • LPI can only be realized by diluting emissions (Low EIRP)
    • In time: Increased duty cycle, CW
    • In space: Wide transmitted beam and digital beamforming
    • In frequency: Multi channel concepts.
  • Stealth Targets
  • Improved detection and tracking performance for targets with low RCS
  • Will require high EIRP and large bandwidth
  • Might require multi static modes

Air Systems Division

future requirements 3
Future Requirements (3)
  • Multifunction
  • Surveillance radar, Fire control radar, Terrestrial comms, Satellite comms, ESM, ECM
  • Benefits claimed for functional integration:
    • Common antenna system at optimum location
    • Increased flexibility in hardware allocation
    • Increased electromagnetic compatibility
    • Reduced radar signature
    • Reduced number of antennas
    • Reduction / elimination of electromagnetic blockage
    • Reduced handover time between functions.

Air Systems Division

future requirements 4
Future Requirements (4)
  • Non Cooperative Target Recognition (NCTR)
  • High resolution range profiling (< 1 m resolution)
    • Short pulses and thus large bandwidth wave forms
  • Jet Engine Modulation (JEM)
    • Emissions at shorter wavelength
    • High sample rate / high PRF for unambiguous spectrum
    • Good close in phase noise performance
  • Other techniques
    • Polarimetry
    • Multi static radar

Air Systems Division

radar modes and architectures

Radar Modes and Architectures

Air Systems Division

radar modes and architectures 1
Radar Modes and Architectures (1)

Major Choices on Waveforms

  • Classical
  • Main design issues for the selection of waveforms
    • Range resolution, accuracy and ambiguity
    • Doppler resolution, accuracy and ambiguity
    • Clutter cancelling
    • Multi target performance
  • Narrow band pulse Doppler waveforms
    • Variety of parameters in frequency, pulse width and PRI

Air Systems Division

radar modes and architectures 2
Radar Modes and Architectures (2)

Major Choices on Waveforms

  • Non classical
  • FM-CW waveforms
  • Passive radar
    • Use of transmission of opportunity to perform radar functions
  • High range resolution
    • Target separation, isolation of target points for NCTR purposes, improved detectability in clutter
    • Short pulse, pulse compression, deramp or stretched waveform, step frequency

Air Systems Division

radar modes and architectures 3
Radar Modes and Architectures (3)

Major Choices on Transmitted Power

  • Compromise between peak power and duty cycle
  • Influenced by transmitter technology.
  • Transmitted RF pulses have to contain sufficient energy to:
  • Detect a target with specified RCS at a specified range
  • Overcome environmental noise effects
  • Overcome path losses
  • Overcome system losses
  • Overcome man made noise sources

Air Systems Division

radar modes and architectures 4
Radar Modes and Architectures (4)

Major Choices on Receiver Selectivity

RF filtering on multi frequency radars offers no rejection of in band interference

IF filters, though effective, are not ideal and therefore offer only limited protection to interferers on nearby frequencies

IF filter design has to balance in band performance against out of band rejection

Traditionally filters have been designed to meet radar requirements and are thus not optimized for the rejection of communication signals

Digital techniques may give the compensation for some IF filter limitations

Air Systems Division

radar modes and architectures 5
Radar Modes and Architectures (5)

Major Choices on Beamwidth

Radar antennas are designed to concentrate RF energy in the wanted direction and suppress radiation in other directions

  • Choice of beamwidth is related to:
  • Requirements on detection range (power aperture product)
    • Compromise between average power and antenna gain
  • Requirements on angular resolution and accuracy

Air Systems Division

radar modes and architectures 6
Radar Modes and Architectures (6)

Techniques Facilitating Sharing (1/4)

  • Receivers with high dynamic range
  • Minimize the chance of unwanted intermodulation products being generated by interfering signals
  • Reduce the risk of receiver saturation
  • Analogue-Digital converters currently set the limits of achievable dynamic range, regardless of the receiver
  • There is no advantage in the detection of small targets in the presence of low level interference
  • Main beam sector blanking
  • Protect other RF receivers in specific direction
  • When applied in networked radars, complete volume coverage can be conserved

Air Systems Division

radar modes and architectures 7
Radar Modes and Architectures (7)

Techniques Facilitating Sharing (2/4)

  • Narrowing of the beam
  • Minimize the width of the transmitted beam of an array antenna
  • Improves the received signal level
  • Drawback is an increase in update time
  • Long pulses
  • Longer pulses allows a reduction in peak power
  • Range resolution requirements dictate the use of pulse coding to maintain bandwidth
  • Short range performance requirements often dictate the use of additional short pulses, thus increasing spectrum usage

Air Systems Division

radar modes and architectures 8
Radar Modes and Architectures (8)

Techniques Facilitating Sharing (3/4)

  • Look back
  • Reduction of false detections due to interference
  • Can only be applied with phased arrays
  • Coverage may degrade when the number of interference sources increases.
  • Spread spectrum techniques
  • Application of conventional DSSS techniques are equivalent to phase coded pulse compression techniques.
  • Multi-user CDMA detection techniques could possibly be applied to improve interference suppression
    • Drawback of multi-user detection is as a minimum an increase in the processing load and the complexity of the required hardware.

Air Systems Division

radar modes and architectures 9
Radar Modes and Architectures (9)

Techniques Facilitating Sharing (4/4)

  • Frequency planning
  • Possible when the interference exhibits a certain regularity
  • Consultation between users of the frequency band can lead to frequency coordination
  • FMCW mode
  • Improved selectivity in comparison with pulse radars
  • CW interference in the instantaneous radar band will cause desensitization

Air Systems Division

radar modes and architectures 10
Radar Modes and Architectures (10)

Radar Modes toward full Mitigation

To achieve optimised mitigation, it is required that cooperative arrangements aremade between users of the band. Two modes can be used:

  • Radar modes for frequency division
  • Determine bandwidth of sub-bands required for different users
  • Divide sub-bands with sufficient frequency separation
  • Allocation of a set of sub-bands spread over the available frequency range will be required
  • Radar modes for spatial division
  • Determine spatial sections to radiate
  • Separate spatial areas by a safety margin

Air Systems Division

radar modes and architectures 11
Radar Modes and Architectures (11)

Radar Modes toward partial Mitigation

Burn through mode: Improved S/(N+I) at the expense of update rate

Frequency control mode: Does not work for unstable spectrum (frequency hopping transmitters) or when the whole band is occupied

Sidelobe control mode: Complex technique that can only be applied for a limited number of interference sources

Interference suppression mode: Improve resistance against interference at the expense of an increased system complexity and reduction in performance

Air Systems Division

thank you for your attention

Thank you for your attention !

Air Systems Division

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