Airbone Radar Applications by Wg Cdr Anupam Tiwari

Airborne Radar: Anupam Tiwari
1

 Introduction to Radar
 Airborne Radar on Different aircrafts
 Applications
 Indian AEW&C
 Mil Standards
 Conclusion
Airborne Radar: Anupam Tiwari 2

 Radio Detection and Ranging (RADAR).
 Microwaves
 RADAR uses electromagnetic waves to
remote-sense the position, velocity and
identifying characteristics of targets.
 Transmitter, Antenna, Receiver, Processor
and Display.

 Platform(ground/air/sea)
 Mono-static/bi-static.
 Primary/secondary.
 Coherent/Non-coherent
 Pulsed/CW(as per waveform)
 As per Antenna technology , MESA, PESA,
AESA, ESA, MSA, multirole.

 Radar altimeters developed in the 1930’s called FM - CW
radar(Continuous Wave radar.)
 First AI airborne radar 1940 (outside, lot of Drag), German in 1944
 First cavity magnetron 1940, radar (inside Radom(Nose)
 First deployed Airborne Radar ”Wellington Bomber “1942
5Airborne Radar: Anupam Tiwari

Active Phased
T/R Modules ADC
Digital Beam
Forming
LATEST TREND IN RADAR

 Waveform Generation(Crystal or DDS)
 HV Power
 Modulation
 Power Amplifier
 Waveguide
 T/R switch

 LNA
 IF (Intermediate Frequency)
 DSP
 I/Q processing, Filter Banks(Doppler
Frequency) FFT

 PPI
 RHI( Range Height)
 Raster
 A –Scope(amp, time)
 B-scope( range ,Az)

Presence of target (detection )
Range (distance and direction)
Received signal strength
Radial velocity (Doppler frequency shift)
Spatial distribution (mapping)
Various target characteristics
Particle size (e.g., precipitation), Surface roughness,
Water content (e.g., soil, snow)
Motion characteristics (e.g., aircraft engine rotation
rate, breathing) Surface displacement (e.g., subsidence)

Imaging RADAR was not developed until the 1950s (after World War
II). Since then, side-looking airborne radar (SLAR) has been used
to get detailed images of enemy sites along the edge of the flight
field. SLAR is usually a real aperture radar. The longer the
antenna (but there is limitation), the better the spatial resolution
 Real Aperture Radar (RAR)
 Aperture means antenna
 A fixed length (for example: 1 - 15m)
 Synthetic Aperture Radar (SAR)
 1m (11m) antenna can be synthesized electronically into a 600m
(15 km) synthetic length.
 Most (air-, space-borne) radar systems now use SAR.

 PRF
 The Doppler Dilemma: There is no single PRF that
maximizes both Rmax and Vmax
PRF RANGE DOPPLER
LOW UNAMBIGUOUS AMBIGUOUS
MEDIUM AMBIGUOUS AMBIGUOUS
HIGH AMBIGUOUS UNAMBIGIOUS

 Surveillance Radars(EW)420–450
 Radar Altimeters 4200–4400
 Navigation & Surveillance(8500–9000),(9000–
9200)(9200–9600)
 Search & Rescue(9000–9200)
(9200–9600)(13250–13400)
 Airborne Cloud Radar (94 000)

 Ka, K, and Ku bands: very short wavelengths used in early
airborne radar systems but uncommon today.
 X-band: used extensively on airborne systems for military
reconnaissance and terrain mapping.
 C-band: common on many airborne research systems (CCRS
Convair-580 and NASA AirSAR) and spaceborne systems
(includingERS-1 and 2 and RADARSAT).
 S-band(2-4 GHz): used on board the Russian ALMAZ satellite.
 L-band(1-2 GHz): used onboard American SEASAT and
Japanese JERS-1 satellites and NASA airborne system.
 P-band: longest radar wavelengths, used on NASA
experimental airborne research system.
 Altimeter 4200-4400 MHz

 Peak power, Av Power
 Duty
 PW, PRF
 Frequency
 Pd, Pfa, Coherent/Non -coherent
 Pulse compression

18
In flight, cumulonimbus (Cb) structures can be a major source of danger, due to
turbulence and heavy precipitation.

 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

 Ocean surface scattering measurements were obtained using a 94
GHz airborne cloud radar. In atmospheric research, especially for
cloud studies, MM-wave cloud radars have gained favour because
of their high scattering efficiency, low power consumption and
compact size.
 Transmit Polarization V or H, Receive Polarization V or H
 Peak Power (kW)= 1.2
 PRF (Hz) = 5,000-80,000
 Range Resolution (m) =38/75/ 150
 Noise Figure (dB)= 9.5
 Receiver Bandwidth (MHz)= 1, 2, 4
 3 dB Beamwidth (degree) =0.8 , Sensitivity=-46

 Lower Fuselage C-band Research Radar with
360 degrees horizontal fan beam

 It use of the 4200–4400 MHz band allows for
conveniently small equipment packages
 This band permits good cloud penetration, require
modest amounts of power, and do not require
 Highly directional antennas for satisfy altimeter
requirements.

 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

Power 7 KW(mode Dependent) Air-to Air, Air to ground,
Data link
LRU 5, 150 Kg Compact size
Cooling Liquid (polyalphaolefin) and forced
air
Interface 1553B and Ethernet Software driven and
control , upgradable
Interface with Display Opto-link
MTBF 250 hrs

AIR TO AIR MODES AIR-TO-SURFACE MODES
Long / medium-range look-up / look-down
detection
Mapping – real beam and high-
resolution SAR
Multi-target track-while-search Ground Moving Target Indication
Multi-target engagement (priority tracking) Air-to-ground ranging
ECM immunity Ground Moving Target Tracking
BVR missile data link Sea surface search and tracking
Automatic waveform selection
Countermeasures (ECM) immunity
Targeting integrated with aircraft data link
Short-range auto acquisition and tracking
Single target track

 AESA, RADAR(sector or full scanning)
 6000 FT
 He gas filled
 TEATHER(power , fiber optical for data)
 Wind speed critical for lowering and
uplifting(30 days)

• f = 10 GHz
• λ = 3 cm
• pulse length: τ = 50 ns
• pulse peak power: P = 10 kW
• PRF: f = 50 Hz
• Antenna length: ℓ = 3 m
• Antenna horizontal beamwidth angle: θa = 0.5°
• Antenna vertical beamwidth angle: 50°

 By transmitting pulses at each indicated location, collecting
all of the resulting data, and properly processing it together,
a SAR simulates large phased array antenna extending over
the distance ﬂown while collecting data.
 High resoultion , High BW of waveform(linear FM), good
resolution in cross range (SAR processing)

Parameter SAR RAR
Range Resolution C τ/2 C τ/2 Pulse compression
Cross range
Resolution
Along track
length(L) /2
λ R/Along track (L) Motion and SAR
processing
PRF Min &MAX
2 V/L<PRF
Modes Spot/strip

L-band
23.5 cm
C-band
5.8 cm
X-band
3 cm
a. b. c.
L-band
23.5 cm
C-band
5.8 cm
X-band
3 cm
a. b. c.

37
The main radar is a Raytheon Systems/BAE Systems dual-mode
Synthetic Aperture / Moving Target Indication (SAR/MTI) radar known
as Sentinel Dual Mode Radar Sensor (DMRS)

 send vertically polarized energy and receive only vertically
polarized energy (designated VV)
 send horizontal and receive horizontally polarized energy
(HH),
 send horizontal and receive vertically polarized energy
(HV)
 send vertical and receive horizontally polarized energy
(VH).

41
antenna produces electrical currents focused
on the ground whose induced magnetic
field is measured to determine resistivity of the
Subsurface material.
Researchers use these data to map
the character of the subsurface--groundwater,
rock, ice, glaciers, etc.—
to depths of approx 300 meters

 A low cost, miniature ultra wideband (UWB)
radar is used to detect suspended wires and
other small obstacles at distances exceeding
several hundred feet
 Average output power of less than 10
microwatts

 multimode/multi-frequency airborne radar for imaging and
subsurface sounding.
 The system operates at relatively LF in the band from VHF to
UHF in two different modalities:
(i) nadir-looking sounder in the VHF band (163MHz) an
(ii) side-looking (SAR) in the UHF band with two channels at 450
MHz and 860MHz

 There are two effects that can degrade the
performance of a radar on a moving platform
▪ A non-zero Doppler clutter shift
▪ A widening of the clutter spectrum
 These may be compensated for by two different
techniques
▪ TACCAR (Time Averaged Clutter Coherent Airborne Radar) The change in
center frequency of the clutter spectrum
▪ DPCA (Displaced Phase Center Antenna) The widening of the
clutter spectrum

 Airborne AESA radar , especially for Low
Probability of Intercept (LPI) technique
 Space-Time Adaptive Processing (STAP)
technique
 Radar transmission silence
 PRF agility
 Adaptive beam

Agencies Responsibilities Remarks
Platform Emb-145 from Brazil 01, +03
Antenna AAAU LRDE Indian
System Integration CABS, DRDO
Antenna
AREODYNAMICS
ADA
SPJ system and EW DARE, DLRL
Data Link ,CSM DEAL
Certification CEMILAC

Table : Customized Radar Suite
Instrument Measurement Frequency Platform Resolution
MCoRDS/I
Bed Topography,
Bed Imaging,
Internal Layering
195 MHz
DC-8
P-3
4 m
Accumulation
Radar
Internal Layering 750 MHz P-3 40 cm
Snow Radar
Snow Thickness,
Internal
Layering,
Topography
2-7 GHz
DC-8
P-3
5 cm
Ku-Band
Altimeter
Topography 14 GHz
DC-8
P-3
5 cm

 MIL STD 810 – Environmental
 MIL STD 461 – EMI/EMC
 MIL STD 417- Reliability
 MIL STD 498 –Software
 IEE -12207 – Software
 DO – 297 - Integrated Modular Avionics
 DOD-2167 –Software
 DO-160 – Environmental
 DO-178 – Software
 DO-254 -Hardware

 DGCA(For CIVIL)
 CEMILAC(FOR MILITARY) with its RCMA DDPMAS-2002
 DGAQA(FOR DPSU and MILITARY)
 MIL-461 (EMI/EMC)
 MIL-STD-8591, DoD design criteria: standard airborne
stores, suspension equipment and aircraft-store interface
 MIL-704 F, Aircraft Electric Power Characteristic
 MIL-STD-498 [12] "Software Considerations in Airborne
Systems and Equipment Certification"

 Any Questions?

Airbone Radar Applications by Wg Cdr Anupam Tiwari

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