NASA ISRO Synthetic Aperture Radar (NISAR)

NISAR Science Workshop – 2014Space Applications Centre

L & S Band Airborne SAR Mission

V.Manavala Ramanujam

Space Applications Centre, Ahmedabad

L&S SAR Airborne

2NISAR Science Workshop, SAC Ahmedabad – 17th & 18th Nov. 2014

L&S SAR Airborne

Overview

Introduction Airborne SAR activities in SAC/ISRO L& S Band Airborne SAR requirement System Specifications Imaging Geometry Block Diagram Data Products Conclusion

3NISAR Science Workshop, SAC Ahmedabad – 17th & 18th Nov. 2014

L&S SAR Airborne

DMSAR System SpecificationsAltitude 8.0 Km (nominal)Frequency 5.35 GHz (C-Band)Flight Velocity 120m/s (nominal)Polarization HH/VV ( Single pol. at a time )Incidence Angle 65 to 85 Deg / Left lookingPeak Power 8 kWSlant Range Resolution

1m 3m 5m 10m

Effective Swath 6 Km 25 Km 45 Km 60 KmMin σo(dB) -20 -24 -27 -30

KOSI OLD FLOW DIRECTION

KOSI NEW FLOW DIRECTION

Ahmedabad Airport1m VV Flood affected Region in Bihar-2007

10m VV

20081m

•C-Band Airborne SAR (1992-2005)•Disaster Management SAR (DMSAR)(2005- )

Airborne SAR activities in SAC

4NISAR Science Workshop, SAC Ahmedabad – 17th & 18th Nov. 2014

L&S SAR Airborne

L& S Band Airborne SAR requirements To study the RCS signatures of various features at L & S

frequency bands with variable incidence angles. To demonstrate the utilization of multi-frequency SAR data in

both independent and simultaneous operation modes, from applications point of view.

To demonstrate new hardware systems like SynchronisedOscillator and Central Transmitter (SynOT), Transmit Receive Integrated Module (TRiMs), Payload Controller and Chirp Generator (PLCG), Data Formatter etc.

To verify the Synchronization methodology that is being planned in DFSS.

To check the data formatter sequence that is to be implemented in DFSS.

To establish processing methodology for PRF dithered SAR data.

5NISAR Science Workshop, SAC Ahmedabad – 17th & 18th Nov. 2014

L&S SAR Airborne

Imaging Geometry

Imaging Geometry at 37° Incidence Angle Imaging Geometry at 64° Incidence Angle

Platform: Beechcraft B200 operated by NRSCAircraft Altitude: 8 kmNominal Velocity : 120 m/sLook angle Range:15.70 - 66.20

6NISAR Science Workshop, SAC Ahmedabad – 17th & 18th Nov. 2014

L&S SAR Airborne

System SpecificationsS.N Parameter Specification

1 Operating Frequency 1250MHz(L), 3200MHz(S)

2SAR Operation

Modes

Single - VV/HHDual - VV+VH / HH+HVCompact(CP) - RH+RV / LH+LVQuasi-PolFull-Pol - (HH&HV)1+(VH&VV)2

(PRF - 2000Hz)3 Chirp Bandwidth 25MHz/50MHz/75MHz

4Operational Look

Angle 15.70 - 66.20

5Incidence Angle

Range28° to 73°

6 Antenna Polarization Dual Polarised(H/V)7 Antenna Type Micro strip Patch8 Antenna

ConfigurationCo-Located Antenna

9Effective Radom

Dimensions available for antenna

1.0m (Azimuth) x 0.35m (Elevation)

10 PRF 1000±200 / 2000±200

S.N Parameter Specification

11Imaging Swath

(Nominal)

Overlapped Swath (S+L) 4km to 15km (for 37° to 64° Roll

Bias of Antenna)

12Ground Range

Swath

Near-End Swath 2.25km for 15.70 LACentre Swath 10.25kms for 520 LAFar-End Swath 18.25km for 66.20 LA

13Integrated

Ambiguities<-20dB

14Sigma Naught

Baseline<-25dB (at 520 nominal

lookangle)

15Sigma Naught

Threshold<-20dB

16Radiometric Resolution

3dB-Single Look, 1dB-Multi Look

17 RF Power Transmit 165W (S) & 40W(L)

18Payload Receiver

ConfigurationIF Sampling(S), Baseband

Sampling(L)

7NISAR Science Workshop, SAC Ahmedabad – 17th & 18th Nov. 2014

L&S SAR Airborne

Block DiagramS-SAR

L-SAR

PLCG- Payload controller + Chirp Generator SynOT - Synchronized Oscillator and Central Transmitter SSR- Solid State Recorder GPS – Global Positioning SystemDABF – Data Acquisition and Beam Former INS- Inertial Navigation SystemDCS – Down converter SectionTRiM- Transmit Receive Integrated Module

8NISAR Science Workshop, SAC Ahmedabad – 17th & 18th Nov. 2014

L&S SAR Airborne

Data Products

Modes Image Polarisation Level-0 RAW L1-SLC L1-detected L2-GeoTIFFSingle Pol VV/HH Dual Pol VV+VH/HH+HV Compact Pol RH+RV/LH+LV Quasi Pol QHH+QHV+QVH+QVV Full Pol HH+HV+VH+VV

Level-0 RAW :Payload rawdata data in binary format with auxL1-SLC :Processed single look complex data – float- with Auxiliary dataL1-Detected :Processed detected image -16bit binary - with Auxiliary data L2 :North oriented image in GeoTIFF format - with Auxiliary data

Scene Sizes:Resolution

S-Band L-Band Incidence angle 25MHz 37.5MHz 75MHz4.5X4.5Km 8 X 8 Km 37-50° 10 7 3.37X7 km 14 X14km 50-58° 7.8 5.2 2.610X10 km 20 X20km >58° 7 4.7 2.3

Radiometric accuracy : <2dBRadiometric Stability: <1dB

9NISAR Science Workshop, SAC Ahmedabad – 17th & 18th Nov. 2014

L&S SAR Airborne

Conclusion This airborne SAR is a pre-cursor to the space borne

DFSS development . It will aid in the preparation of applications scientist in

the area of ecosystem, geological, disaster and coastal studies.

A number of new hardware/technologies used in NISAR will be tested in this airborne SAR.

The integrated and tested System will be delivered/Operationalized by 2015-Q3.

10NISAR Science Workshop, SAC Ahmedabad – 17th & 18th Nov. 2014

L&S SAR Airborne