Quellenangabe Institut für Hochfrequenztechnk und...
Transcript of Quellenangabe Institut für Hochfrequenztechnk und...
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1Institut für Hochfrequenztechnk und RadarsystemeQue
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1Institut für Hochfrequenztechnk und Radar
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2Institut für Hochfrequenztechnk und RadarsystemeQue
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2Institut für Hochfrequenztechnk und Radar
SRTM Mission CharacteristicsOrbital altitude 233,1 kmInclination 57,0 ºFlight duration 11 days, 166 revsFlight attitude (roll,pitch,yaw) 301º, 180 º, 0 º, ± 0,1 º, Total payload weight 13405 kg Total payload power/energy 7,14 kW, 9,8 kW peak/903kWhNumber of data tapes 330 equiv. 12250 GbyteCrew members G.Thiele, J.Voss,J.Kavandi, M.Mohri,
K.Kregel, D.L.P.Gorie
Launch /Mission11.-22. February 2000, 17:43 GMTOrbiter/Space ShuttleSTS 99, OV 105 Endeavour
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3Institut für Hochfrequenztechnk und RadarsystemeQue
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3Institut für Hochfrequenztechnk und Radar
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4Institut für Hochfrequenztechnk und RadarsystemeQue
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4Institut für Hochfrequenztechnk und Radar
SRTM Within Shuttle Bay
Remote Sensing Technology Institute
M. Eineder, 30.11.2001
SRTM Space Segment
RX-only-antennas 60 m Mast
TX/RX-antennas
2 Single-Pass-Interferometers:
C-band
C-band
C-band (NASA/NIMA):
225 km swath width
⇒ full coverage (± 60° lat.)
< 10 m relative vertical accuracy
X-band
X-band
X-band (DLR/ASI):
50 km swath width
⇒ partial coverage
< 6 m relative vertical accuracy
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6Institut für Hochfrequenztechnk und RadarsystemeQue
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6Institut für Hochfrequenztechnk und Radar
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7Institut für Hochfrequenztechnk und RadarsystemeQue
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7Institut für Hochfrequenztechnk und Radar
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8Institut für Hochfrequenztechnk und RadarsystemeQue
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8Institut für Hochfrequenztechnk und Radar
X-SAR/SRTM Project Organization
NIMA NASA
DLROberpfaffenhofen
Project Management
ASI
JPL
MOU MOU Letter Agreement
DLRProjectsDirector
Dornier(DSS)
Science Activities
DLR(HF-Institut)
Mission-Operations
DLR(GSOC&HF)
Calibration &Validation DLR(HF-Institut)
System-Engineering DLR(HF-Institut)
Data Processing
DLR(DFD)
Flight Instrument Development
Integration & TestSupport
ContractAMILGEO
Letter Agreement
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9Institut für Hochfrequenztechnk und RadarsystemeQue
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9Institut für Hochfrequenztechnk und Radar
X-SAR/SRTM Height Error(Only X-SAR system)
Distance from nadir over swath / km
H e ig h t E rro r A s sum p tio ns (M id d le o f S w ath )R ela tive (30 seconds) A bso lute (11-days)
A ssum ed Accuracy H eigh t Error A ssum ed Accu racy H eigh t Error
B aseline Tilt A ng le Error 2 a rcsec 3 .0 m 9 a rcsec 13 .4 m
B aseline Leng th E rro r 1 .3 m m 0.8 m 4 .0 m m 2.6 m
Instrum ent Phase E rro r 4 .0 deg 4 .2 m 4 .0 deg 4 .2 m
O verall S ystem Erro r 1 .6 m 1 .6 m 1 .6 m 1 .6 m
T o ta l (R S S ) 5 .5 m 14 .4 m
X-SAR/SRTM Height Error Sources:• Instrument Phase Error• Random Phase Error• Ambiguity Phase Error• Baseline Length Error• Baseline Tilt Angle Error• Atmospheric Error• Position Error• Calibration Error• Slant Range Error• Processing Error
X-SAR/SRTM Performance
Performance Requirements:• Relative Height Accuracy (90 %) < 6 m• Absolute Height Accuracy (90 %) < 16 m
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10Institut für Hochfrequenztechnk und RadarsystemeQue
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10Institut für Hochfrequenztechnk und Radar
WissenschaftExperimente
Missions-Betrieb
Kalibrierung&Validierung
RadarsystemTechnik
DatenVerarbeitung
DLRProjektleitung
Institut für Hochfrequenztechnik
GSOC undInstitut für
Hochfrequenz-technik
Institut für Hochfrequenz-
technik
Institut für Hochfrequenz-
technik
Institut für Hochfrequenz-
technik
DeutschesFernerkundungs
Datenzentrum
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11Institut für Hochfrequenztechnk und RadarsystemeQue
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11Institut für Hochfrequenztechnk und Radar
Deployed 60 m SRTM mastat AEC-ABLE
Stacked mast with cables ( 3m )
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12Institut für Hochfrequenztechnk und RadarsystemeQue
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12Institut für Hochfrequenztechnk und Radar
225km45kmSwath
4,9/37,5°4.9/0.25°5,3/0,28°5.5 /0.14°3 dB Beam Elevat. /Azimuth -19 dB-18 dB -21 dB-20 dBElevation Side Lobe40,0 dB42.8 dB 41,8 dB43.5 dBMain Antenna Gain 0.7m x 8m0.7 m x 12 0.4m x 6m0.4 m x12mMain Antenna Area
1.7 kW3.5 kWRadiated Peak Power60 dBTotal Dynamic Range
25 m / 13 m20 m / 10 mRge Res.10 MHz/20 MHz BW
30m25 mAzimuth Resolution (4 looks)
36.5, 46.5,53, 5836.5,46.5,53,5855.554.5Off Nadir during Mission/°
15- 55 elec.15 - 55 elec.54-55 mech.15-55mech.Adjustable Off-Nadir /Degree >25 dB39 dBPolarization Isolation
5.3 GHz HV5.3 GHz HV9.6 GHz V9.6 GHz VVFrequency, Polarization
C-Band Secondary
C-Band Primary
X-Band Secondary
X-BandPrimary
X-SAR/SRTM Radar Specifications
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13Institut für Hochfrequenztechnk und RadarsystemeQue
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13Institut für Hochfrequenztechnk und Radar
X-SAR Outboard Antenna and Electronics
LNA
ϕ
LNA
ϕ
LNA
ϕ
LNA
ϕ
LNA
ϕ
LNA
ϕ
XDC Mast
Phase control
Phased Array Antenna
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14Institut für Hochfrequenztechnk und RadarsystemeQue
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14Institut für Hochfrequenztechnk und Radar
X-SAR Antenna Characteristics
Elevation angle off boresight / deg Azimuth angle off boresight / deg
Rel
ativ
e in
tens
ity /
dB
Rel
ativ
e in
tens
ity /
dB
Primary Antenna: slotted waveguidearray (transmit & receive)(12 m x 0.4 m)
Secondary Antenna: phased array(6 m x 0.4 m) receive only
Elevation Two Way Pattern Azimuth Two Way Pattern
Remote Sensing Technology Institute
M. Eineder, 30.11.2001
X
C
photo © JPL
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15Institut für Hochfrequenztechnk und RadarsystemeQue
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15Institut für Hochfrequenztechnk und Radar
SRTM Antenna AlignmentExample showing antenna misalignment effects and design to reduce the misalignment
– YOCS
(A) Bending in Y-Z Plane (Roll) (B) Bending in X-Y Plane (Yaw) (C) Twisting along Y Axis (Pitch)
Cross Track
Alo
n g Track
Near
Outboard Antenna Footprint
Inboard Antenna Footprint
Far Cross Track
Alo
ng Track
Near Far
Outboard Antenna Footprint
Inboard Antenna Footprint
Cross Track
Alon
g Track
Near FarOutboard Antenna Footprint
Inboard Antenna Footprint
• Impacts – Lose SNR and swath – Baseline vector change
• The Observable – AODA measurements – Radar echo profiles
• Corrective Measures – Main antenna electronic
steering in elevation
• Impacts – Lose SNR and swath – Baseline vector change
• The Observable – AODA measurements – Radar echo Doppler estimates – Radar echo profiles
• Corrective Measures – Outboard structure adjustment in
yaw – Main antenna electronic steering
in azimuth – Outboard beam tracking
• Impacts – Lose SNR and swath
• The Observable – AODA measurements – Radar echo profiles
• Corrective Measures – Outboard structure adjustment in
pitch – Main antenna electronic steering
in azimuth – Outboard beam tracking
– Y ICS
ZOCS
ZICS
XICS II XOCS
– YOCS
– Y ICS
X ICS X OCSXICS
ZIC S II ZOCS Y ICS = Y OCS
X ICS
XOCS
ZOCS ZICS
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16Institut für Hochfrequenztechnk und RadarsystemeQue
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16Institut für Hochfrequenztechnk und Radar
117 tapes for X-SARrecording time 59 minutes max90 Mbit/sec datarate50 playbacks, 2 minutes each
SRTM Data Recording on board
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17Institut für Hochfrequenztechnk und RadarsystemeQue
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17Institut für Hochfrequenztechnk und Radar
System Parameters of the X-SAR InstrumentHistorical development and restrictions:
• Orbit height ranging from 233 km to 249 km (coverage requirement of C-Radar)• PRF limited to eleven fixed values ranging from 1240 Hz up to 1736 Hz• Off-nadir angle higher than 51 degrees to avoid interference with the Attitude and
Orbit Determination Avionics (AODA)
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18Institut für Hochfrequenztechnk und RadarsystemeQue
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18Institut für Hochfrequenztechnk und Radar
Cargo Bay Payload Layout
Star Tracker(STA )
GPS A ntenna
X-B and Outb oard Elec tronics
F ORE
AF T
C an is terOutb oard Supp ort Stru ctu re (O SS)
C -Band M ain A ntenn aL -Band M ain A ntenna
X-B and M a in A ntenn a
GPS A ntenna
Pallet A ntenn a Trun ion
A ntenna C ore Stru ctu re (A CS)
A OD A Su ppo rt Pane l (ASP)
A stros Targ et Tracker (ATT )
IR U
An ten na Tru nio n (ATS)
GPS An ten na
GPS A ntenn a
M A ST
M ilkstoo l
A ntenna C ontrol le r (CP DU )
GPS A ntenna
LED Targets (OTA )Fl ip Hinge
X-Band Outb oard An ten na
A FT Elec tro nics Panel (A EP)
GPS Receivers
A FT
X-Band 2nd Ch an nel Electron ics
Elec . D is tance M eter (ED M )
C -To -L D ow nconverte r
O utbo ard A ntenna B racketOu tboard C orner C ube
C -Band Ou tboard A ntenna
B eam A uto-Tracker
Courtesy JPL
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19Institut für Hochfrequenztechnk und RadarsystemeQue
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19Institut für Hochfrequenztechnk und Radar
Payload Flight Segment Configuration
XAE: X ANTENNA ELECTRONICS XCB: X COMBINER BOX XDC: X DOWN-CONVERTER XDU: X DISTRIBUTION UNIT XOA: X OUTBOARD ANTENNA (PANELS) GPSA-2a/b: GPS ANTENNAS OTA: OPTICAL TARGET ARRAYS GPSA-2a/b: GPS ANTENNA/LNA (OUTBOARD) BAT: BEAM AUTO- TRACKER CLDC: C-TO-L DOWN-CONVERTER & CAL COA: C OUTBOARD ANTENNA COR: CAL OPTICAL RECEIVER CPDU: CNTL & PWR DIST. UNIT OAS: OUTBOARD ANTENNA SUBSYSTEM
AODA SENSOR
PANEL (ASP)
STA
IRU
ATT SA
DSCU1
DSCU2
HVE
RFE
TSS
DCE2
SIUDAE
IFD
RAE
GPSR- 1/2
CSM
CATSMDA
RIO
CTTA1
CTTA2
EXCITER1
EXCITER2
VSN
CV DRVR/RCVR
CH DRVR/RCVR
LH DRVR/RCVR
LV DRVR/RCVR
RC
BS
DCE1
NEWOLD MODC-RADAR
NEWOLD MODSMS
NEWAODA
NEWOLD MODX-RADAR
LEGEND:
PDA
MPMC
PHRR1
PHRR2
PHRR3
APC-1/2
DDRE
APC1/2: AODA PROCESSING COMPUTERS
DDRE: DIGITAL DATA ROUTING ELECTRONICS
HDDT: HIGH DENSITY DIGITAL TAPE
PHRR: PAYLOAD HIGH RATE RECORDER
RIC: RECORDER INTERFACE CONTROL
RDA: RADAR DATA ANALYZERS
DDHA1
DDHA2
DDHA3
DDHA4
LVE
C/AI: CAL/ANTENNA INTERFACE COT: CAL OPTICAL TRANSMITTER DDHA1-4: DIGITAL DATA HANDLING ASSEMBLY RFES: RF ELECTRONICS SUBSYSTEM RCBS: REDUNDANCY, CAL & BITE SELECT VSN: VIDEO STEERING NETWORK
CTTA: CNTL, TMG AND TLM ASSEMBLY DSCU: DEPLOY/STOW CONTROL UNIT MPMC: MAST POWER AND MOTOR CONTROL PDA: POWER DISTRIBUTION ASSEMBLY RIO: REDUNDANT I/O HVE: HIGH VOLTAGE ELECTRONICS LVE: LOW VOLTAGE ELECTRONICS DCE1/2: X DATA & CONTROL ELECTRONICS RFE: X RADIO FREQUENCY ELECTRONICS
X-ELEC. PLATE
DSCU PLATE
PDA PLATE
CTTA PLATE
DDHA PLATE
RFES PLATE
AFT ELECTRONICS PANEL (AEP)
CAN
MILK STOOL
YA
PAFA
FLIP HINGE
MAST
XBS
XTSTR
IDR
IVE
ACS/ATS
GPSA- 1a
GPSA- 1b
XMA
LMA
CM
A
CARGO BAYAFT DECK PALLET SMS
PALLET SMSCARGO BAYAFT DECK
CMA: C MAIN ANTENNA LMA: L MAIN ANTENNA GPSA-1a/b: GPS ANTENNAS ACS: ANT. CORE STRUCTURE ATS: ANT. TRUNION STRUCTURE CAT: CANT. ATTACHMENT TRUSS CAN: CANISTER CSM: CONNECTOR SEPARATION
MECHANSIM FA: FLIP ACTUATOR LPS: LAUNCH PIN STRUCTURE PA: PITCH ACTUATOR PICA: PYROTECHNIC INITIATOR
CONTROL ASSEBLY SMDA: SUBSTITUTE MOTOR DRIVE
ASSEMBLY TSS: TRUSS SUPP. STRUCTURE YA: YAW ACTUATOR XBS: X-ANT. BACK STRUCTURE XTS: X-ANT. TRUNION STRUCTURE XMA: X PRIMARY ANTENNA
NOTE: PLACEMENT OF HARDWARE PIECES IN THIS DWG MAY NOT CORRESPOND TO FLIGHT CONFIGURATION
APC1 APC2
RIC
RDA3
RDA1
RDA2
NOT SHOWN: PHRR SPARES AND APC/RIC/RDA SPARES; ALSO HDDTs > 264.
EDM 1-4
ATT EA
PSU
XOA
OTA
XCB
XDC
XAECLDC
GPSA- 2b
GPSA- 2a
OUTBOARD SUPPORT
STRUCTURE(OSS)
CO
AP
BAT
XDU
LPS
C/A
I; CO
T
COR
OAS
CPDU
COA
DAE: DIGITAL ADAPTER ELECTRONICS IFD: INTERMEDIATE FREQ & DEMODULATION UNIT PSU: POWER SUPPLY UNIT RAE: RF ADAPTER ELECTRONICS ATT SA: ASTROS TARGET TRACKER SENSOR ASSEMBLY ATT EA: ATT ELECTRONICS ASSEMBLY GPSR-1/2: GPS RECEIVERS EDM: ELECTRONICS DISTANCE METER IRU: INERTIAL REFERENCE UNIT SIU: SENSOR INTERFACE UNIT STA: STAR TRACKER ASSEMBLY
PICA
COLD-GAS TANKS
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20Institut für Hochfrequenztechnk und RadarsystemeQue
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20Institut für Hochfrequenztechnk und Radar
PRF Selection / Timing
Fixed PRF:
1674 Hz
Pulse bandwidth: 9.5 MHz
Down link data rate: 45 Mbit/s
Pulse length: 40 µs
Quantization: 8 bits/sample
Echo sampling frequency: 11.25 MHz
PRF-Restrictions
PRF / Hz
Offn
adir
ang l
e /
deg
Timing at Equator Timing at +/- 57 deg latitude
Time relative to start of transmit pulse / microsecTime relative to start of transmit pulse / microsec
Data Window
Antenna Boresight
Nadir Return
Transmit Pulse
Echo Profile
Data Window
Antenna Boresight
Nadir Return
Transmit Pulse
Echo Profile
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21Institut für Hochfrequenztechnk und RadarsystemeQue
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21Institut für Hochfrequenztechnk und Radar
Instrument Performance Characteristics
Signal-to-Noise Ratio
Transmit peak power:3300 W
Noise figure: 5.25 dB Noise figure: 2.52 dB
σ : SRL1 / SRL20
SNRadc
SNRimg
SNRadc_out
SNRvid
Distance from nadir / km
SN
R /
dB
Primary System
SNRadc
SNRimg
SNRadc_out
SNRvid
Distance from nadir / km
SN
R /
dB
Secondary System
RASR
Total ASR
Distance from nadir / km
Amb
to s
ig/
dB
Primary System
CrosstermASR
AASR
Secondary System
RASR
Total ASR
Distance from nadir / kmAm
bto
sig
/ dB
CrosstermASR
AASR
Ambiguities
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22Institut für Hochfrequenztechnk und RadarsystemeQue
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22Institut für Hochfrequenztechnk und Radar
Telemetry System
Mission PlanningSystem
Command System
Performance EstimatorSystem (PE)
Radar Data Analysis
Performance AnalysisSystem (PA)
>12 hours before DT
> 6 hours before DT
during DT
during / after DT
Mission Planning and Operations System•Data Take start and stop times•Selection of radar parameters•Downlink and play back times•Tape management
•Check parameter selection•optimize gain setting
•Generate command sequence•Uplink onboard sequencer load•Real-time commanding
•Monitor instrument health•Monitor instrument function
•Monitor DT performance (echo profile)•Monitor parameter settings
•High rate data analysis (bit error rate)•Antenna alignment (Doppler centroids)•Quick-look radar image processing•Quick-look interferometry
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23Institut für Hochfrequenztechnk und RadarsystemeQue
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23Institut für Hochfrequenztechnk und Radar
C/X Joint Operations Agreement1. Priorities C-band DEM, X-band DEM
2. PHRR Operations PHRR 3 =X, X reassign to CA or CB, PHRR4- Xreplace with spare,
3. DDRE Contingency activate bypass,
4. High-Rate Live Downlink whenever possible, channels sequentially by DT
5. High Rate Playback 2 minutes of last DT, ratio C:X=2:1, contingencies
6. Command Uplink AODA, real-time, sequencer loads
7. Datatake Planning joint C,X DT’s same start/stop, no short-term plan
8. Antenna Tilt X-antenna tilt < 0 deg, Tilt CMD by C- Control
9. Beam Adaptive Tracker use decided by C-Radar
10. Milkstool (beam alignment) optimize C and X alignment
11. Energy Contingency shortage shared
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24Institut für Hochfrequenztechnk und RadarsystemeQue
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24Institut für Hochfrequenztechnk und Radar
X-SAR Operational Constraints3: The Orbiter attitude should be constrained so that the sun does not shine on the radiating surfaces of the SIR-C/X-SAR antennas. If the Orbiter must maneuver to an attitude that violates this constraint, antenna surface temperatures shall not exceed: (1) +40 deg C (inboard and outboard, antennas non-operating) or (2) +30 deg C (inboard and outboard, antennas operating);
7:X-SAR tri-drive operations. For loss of one motor drive system, nominal experiment ops may continue. For loss of two motor drive systems, use of the remaining motor system will be minimized. EVA capability exists to stow antenna if the third motor system fails.
16:Power up of X-SAR outboard heater electronics (PSU) when temperature is below –30 deg C. If external environmental temperatures near the X-SAR outboard electronics (XOE) are below -30 deg C,the PSU shall not be powered-on by the crew (SSP/S9). The Orbiter shall maneuver to warm the XOE toabove -30 deg C so that switch-on may occur.
17: Potential damage to X-SAR outboard electronics (XOE) boxes if external environmental temperaturesexceed -40 deg C when the PSU is unpowered (SSP1/S9). If external environmental temperaturesexceed -30 deg C when PSU is unpowered, the Orbiter will maneuver to a warmer attitude. Prevent permanent damage to the X-SAR outboard electronics.
20:The X-SAR antennas should not be allowed to get colder than -117 deg C. If X-SAR antenna temperatures drop below -112° C, maneuver the Orbiter to a warmer attitude.The X-SAR antennas have been qualified from -150 deg C to 70 deg C (non-operating). The X-SAR components that are the limiting factors are the radiating waveguides and the reinforcement frame. However, the manufacturer recommends not exceeding -117 deg C to +40 deg C to avoid degradation of antenna performance.
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25Institut für Hochfrequenztechnk und RadarsystemeQue
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25Institut für Hochfrequenztechnk und Radar
Specific X-SAR Crew Activities (crew procedures)
• X-SAR activationMain antenna deploy
• PHRR 3, Tape changes
• X-SAR deactivationMain antenna stow
Nominal Operations Non nominal Operations POCC support
X-Ops
C-InstrumentAMS
X-OpsX-Ops
C-InstrumentAMS
• X-SAR B CMD Swap source PSP1(2) to 2(1)•Tilt angle Display Lookup Table
• Tilt Mode Sel Man• Antenna OVD Ply (ANT POS)• Tilt 3(4)ENA• ANT POS(ANT S TO)tb-LAT(gray)• ANT HTR 1(2,3),tb- bp
• No confirm PSU Power On• No PSU Power On• No confirm PSU Power Off• No PSU Power Off
• EVA-Restow X-SAR Antenna
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26Institut für Hochfrequenztechnk und RadarsystemeQue
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26Institut für Hochfrequenztechnk und Radar
X-SAR/SRTM Data Flow
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27Institut für Hochfrequenztechnk und RadarsystemeQue
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27Institut für Hochfrequenztechnk und Radar
X-SAR Calibration
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28Institut für Hochfrequenztechnk und RadarsystemeQue
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28Institut für Hochfrequenztechnk und Radar
X-SAR/SRTM Error Budget
Performance Requirements
• Relative Height Accuracy(90 %) <6 m
• Absolute Height Accuracy(90 %) <16 m
X-SAR/SRTM Height Error Sources
•Baseline Tilt Angle
•Baseline Length
Instrument Phase
•Random Phase
Ambiguity Phase
• Atmosphere
• Position
• Calibration
• Slant Range
• Processing
14,4 m5,5 mTotal4,2 m4,o deg4,2 m4,0 degInstrument Phase2,6 m4,0 mm0,8 m1,3 mmBaseline Length13,4 m9 arcsec3,0 m2 arcsecBaseline Tilt AngleErrorAccuracyErrorAccuracyError Type
Absolute (11 Days)Relative (30 seconds)Height Error Examples (Middle of Swath)
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29Institut für Hochfrequenztechnk und RadarsystemeQue
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29Institut für Hochfrequenztechnk und Radar
Calibration Concept
Ocean Sea Level
Calibration
• Estimation of systematic errors• Monitoring of system parameters and instrument performance• Characterization of instrument parameters• Development of calibration models (parameter drifts as a function of time and temperature )
• Ocean as reference height (sea surface height model)Known orbit with respect to WGS 84 ellipsoid
Ground Control
PointOcean Sea
Level Calibration
Measured height
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30Institut für Hochfrequenztechnk und RadarsystemeQue
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30Institut für Hochfrequenztechnk und Radar
X-SAR/SRTM Calibration Phases
• Preflight concept definition phase including sensor characterization, calibration algorithm development and implementation
• Ground campaigns during the mission
• 6 months commissioning phase: generation of static and dynamic calibration files, analysis and modeling of parameter drifts with temperature and time
• Operational calibration and validation
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31Institut für Hochfrequenztechnk und RadarsystemeQue
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31Institut für Hochfrequenztechnk und Radar
Required data for X-SAR calibration/validation
DLR/User
ERS-1altimeter data
TOPEX-POSIDON data
AODA
MPOS
X-SAR
DLR/User
X-SAR
DLR/User
DLR/User
GCP data base
High precision DEMs
Tide tables
Geoid undulations
AODA-PADR file
X-SAR HK data
Ocean datatakes
Calibration test sites (CRs)
Cal tone
Maps
GDPS X-GDPS
NIMA/JPL
DLR/User
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32Institut für Hochfrequenztechnk und RadarsystemeQue
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32Institut für Hochfrequenztechnk und Radar
AODA System OverviewInstruments Function Accuracy Rate
X Y ZGPS2 GPSR &4 GPSA
C-band area centroids (ACS and OCS) state vectors - Position (WGS 84) - Velocity (WGS 84)Time tag
1m0.05m/s
1m0.05m/s
1m0.05m/s 1 Hz
Star TrackerAssembly (STA)
Estimates inertial attitude of ICSSTA boresight orientation wrt inertial space
InertialReferenceUnit (IRU)
Propagation of inertial attitudes between STA updates
roll5.0
0.05arcsec
pitch36.0
0.05arsec
yaw 5.0
0.0.5arcsec
1 Hz
ASTROS (ATT)& Optical TargetAssembly (OTA)
Estimates the relative attitude and position of the OSS ->C-InSAR baseline and support antenna alignmentTracks 3 LED targets at 60 m distance
0.8arcsec
- 0.8arcsec
4 Hz
ElectronicDistance Meter(EDM)
Distance measurement to OCS and X-SAR backstructure- 2 for ICS to OCS vector length determination (red.)- 2 for ICS to inboard X-SAR area centroid Y & Z offsetdetermination
- 0.5mm
0.5 mm -0.5mm
0.5Hz
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33Institut für Hochfrequenztechnk und RadarsystemeQue
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AODA Flight System Functional Diagram
APC 28VDC Cabin Pwr
serial digital i/o
MET/SIO sync
MET/SIO clk
X-OSTT
serial digital data
power
serial digital i/oanalog data
power
pulse trains & clocks
analog datapower
serial digital i/opower
OTA(3 arrays)GPSA-2
GPSA-1
ATTEA
IRU
STA
PCB128VDC
Main Pwr
serial digital dataPDI
pwr/rf
downlink
power
LNA
LNA
SIU
AMTC: Auto Mast Twist CompensationAPC: AODA Processing Computer (Thinkpad)ATT: ASTROS Target TrackerDAE: Digital Adapter ElectronicsEA: Electronics Assembly (ATT)EDM: Electronic Distance MeterGPSA-1: GPS Antennae Set 1 (inboard)GPSA-2: GPS Antennae Set 2 (outboard)GPSR: GPS ReceiverIRU: Inertial Reference UnitLNA: Low Noise AmplifierMET: Mission Elapsed TimeMPMC: Mast Power & Motor ControlOSTT: One Second Time-TickOTA: Optical Target AssemblyPCB: Power Control BoxPDI: Payload Data InterleaverSA: Sensor Assembly (ATT)SIO: Serial Input/Output (shuttle att/sv data)SIU: Sensor Interface UnitSTA: Star Tracker Assembly
Payload Bay and Outboard Support Structure Crew Cabin
C-RADARMPMC
discrete (bi-level) i/o
discrete (bi-level) i/o
GPSR-1
GPSR-2
LNA
MET/SIO data
X-RADAR DAE
OPS RCRD
serial digital i/o (x4)
power (x4)EDM(x4)
ATTSA
ctrl/data
MET/SIO sync
serial digital data
powerMET/SIO sync
AMTC discrete
output signals
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34Institut für Hochfrequenztechnk und RadarsystemeQue
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34Institut für Hochfrequenztechnk und Radar
SRTM Baseline Measurement Breakdown
Example showing how the baseline measurement is broken down into respective subsystems
GPS Antenna 1
GPS Antenna 2
Inboard C-Band Phase Center
Inboard Coordinate System Origin
Outboard Coordinate System Origin
A
P i
G 2
Outboard C-Band Phase Center
B
Po
To Origin of WGS84
P
Inboard Area Centroid
Eo
E i
B = (
)
-A P i P o )
= (P -WGSGPSxP
WGSicsM ICS
ocsM+
ICSocsMWGS
icsM A- Pi+G x
- E i ( Eo+
Ei+
To Origin of WGS84
AODA
GDPS
SMS
C-RADAR
Measurement Responsibility
GPS2PWhere :
= ICS to OCS Origin VectorA
ICSocsM WGS
icsM, = Rotation Matrices to convert between Coordinate Systems
= Location of Antenna Area Centroids,P i Po
= Offset Vectors between Area Centroids and the True Phase Center of Antennas
,E i Eo
G x = Location of the x th GPS Antenna ICS/OCS
B
P = Phase Center Position Vector= Interferometric Baseline Vector
= Location of the x th GPS antenna in WGS84GPSxP
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35Institut für Hochfrequenztechnk und Radar
INSTRUMENT CALIBRATION
Interferometric phase:
( )( )
(CT1attCTtestcpRAEtestcp1ant
,LNAXCBi,switchi,LNAant
outboom
i,2CT1CT
21int
615.36
61
−−−−
−−
−
Φ+Φ−Φ−Φ+
Φ−Φ−Φ−
Φ+
Φ−Φ+
Φ−Φ−=Φ
∑
∑
• caltone estimation
• phase variation of 263MHz signal on boom cablefrom phase detector
correction terms from preflight instrumentcharacterization
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36Institut für Hochfrequenztechnk und RadarsystemeQue
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36Institut für Hochfrequenztechnk und Radar
Correction and Calibration of the X-SAR Data
Antenna 2LNA's
XCB
XDC
RFE
RAE
IFD
Antenna 1
Boom
135MHz
1052MHz
263MHz
WG
Secondary Channel Primary Channel
STALO
Critical Parts of the X-SAR Radar electronics
• Phase variation of radar receive signalin the six individual paths: antenna panel to XCB including LNA’sand phase shifters
• Down-conversion using 263 MHz signalgenerated in the RFE (1052 MHz) and distributedover the mast to XDC, ± 4 deg phase variationat 263 MHz multiplied by 36 in down-conversion
•Phase variation of radar receive signal running at 135 MHz over the mast cable: ± 2deg over a temperature range between -10oC and -50oC
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test coupler
Antenna
Panel #1
263 MHz
Channel 1
switch box
RX-Gain
XCB
XDC
IFD
RAE
Boom
RX-Gain
Channel 2
RFE
WG
1052MHz
cal-tonegenerator
cal-tonegenerator
downconversion
downconv.
LNA
I/Q I/Q90 MHz
RADAR RECEIVE SIGNALS
ΔΦ
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38Institut für Hochfrequenztechnk und RadarsystemeQue
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38Institut für Hochfrequenztechnk und Radar
D1-D18 1.5 m Corner reflectors GermanyD19-D24 3m Corner reflectorsD25-D27 RU1-Russia-Kitab-1 RU2-Russia-Zelenchukskaya-2RU3-Russia-Zvenigorod-3RU4-Russia-Irkutsk-4RU5-Russia-Bear_Lakes-5CH1-5 Switzerland-1-5SA1-2 South-Africa-1-2 NO1-2 Norway-1-2 EG1-3 Aegypten-1-3 BK1-6 Baikal-1-6KG1-Kirgisien-1-4 IS1-2 MIRBATS-ISRAELIS3-673-HILL-ISRAELIS4-MITSPE-ZOHAR-ISRAELIS5-HIDDEN-HILL-ISRAELIS6-SEDE-ZIN/minhat-north-ISRA IS7-SEDE-ZIN/minhat-south-ISRA IS8-BEER-SHEVA/goral-ISRAELIS9-BEER-SHEVA/hatserim-ISRAEL
X-SAR/SRTM Calibration Sites
Remote Sensing Technology Institute
M. Eineder, 30.11.2001
DT 146.190
SRTM Calibration: Uses Ocean Data Takes
As reference surface, instantaneous ocean heights including gravity, tides,barometric pressure are used. Precision is in centimeter range.Ocean data are provided by Geoforschungszentrum Potsdam (GFZ).
Institut für Hochfrequenztechnik und Radarsysteme 9
•Data take start and stop•window position•gain selection
Downlink/Playback
TDRSS coverage
XSAR/SRTM Mission Planning
Tape management
Remote Sensing Technology Institute
M. Eineder, 30.11.2001
8500 kmRelative Accuracy 6 m (84%)
Absolute Accuracy 16 m (99%)
Result: Long Time Stability on DT 146.190
Azimuth cut of DEM error over a long ocean data take. Absolute accuracy requirement (16m, 90%) is easily met, the relative requirement (6 m, 90%) only after reduction of thermalnoise.
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Ocean Calibration
• Height error:
truthgroundmeas hhh −−=δ
• Error contributions from baseline length/tilt, phase and orbit height offsets
[ ]⎥⎥⎥⎥
⎦
⎤
⎢⎢⎢⎢
⎣
⎡
δΦδ
δαδ
δδδδ=δ Φα
H
b
h H,h,h,hb,h
• MAP estimation based on prior information provided by AODAproblem sufficient SNR at 55deg incidence angle ?
Two iterations to determine static and dynamic calibration file
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40Institut für Hochfrequenztechnk und RadarsystemeQue
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40Institut für Hochfrequenztechnk und Radar
SRTM Calibration:measured Height over Ocean
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41Institut für Hochfrequenztechnk und Radar
Geometric Calibration
• Differential range delays from data itself by cross correlationof the speckle patterns between the two interferometric channels
• Common range delay, time tag/velocity biases using cornerreflectors, calibration sites: Oberpfaffenhofen, Mojave Desert, Australia
• Baseline length/tilt, orbit, phase offsets: estimation from short ocean data takes before/after ocean-land crossing or from GCP’s
• Residual phase errors (e.g. multipath) and system stability: long oceandata takes at the beginning and end of the mission
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42Institut für Hochfrequenztechnk und Radar
SRTM Data Products
DTED (Digital Terrain Elevation Data) ⇒ ITED (Interferometric Terrain Elevation Data)
• 1 degree x 1 degree cell; origin in SW corner• elevations in meter• intervals in Arc Seconds (DTED 1: posts every 3 arcsec, DTED 2: 1 arcsec)• datum: vertical = mean sea level, horizontal = WGS 84• Specification ITED level 2
C-Band X-Bandhorizontal absolute accuracy < 20 m < 20 m ( 90% circular error WGS)vertical absolute accuracy < 16 m < 16 m ( 90% linear error WGS)
horizontal relative accuracy < 15 m <15 m ( 90% circular error WGS)vertical relative accuracy < 10 m < 6 m ( 90% linear error WGS)
HEP (Hight Error Map) ⇒TPDSlope Map ⇒ TBD
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43Institut für Hochfrequenztechnk und RadarsystemeQue
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43Institut für Hochfrequenztechnk und Radar
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44Institut für Hochfrequenztechnk und RadarsystemeQue
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44Institut für Hochfrequenztechnk und Radar
X-SAR/SRTM Swaths over Bavaria (Calibration site)
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SIR-C Results
Remote Sensing Technology Institute
M. Eineder, 30.11.2001
SRTM-Fact Sheet• Orbit height: 233 km
• Mission duration: 11 days
• Cost:US Mission: $ 142MShuttle Start: $ 50 MX-SAR: $ 40 M
• Data amount: ca.10 TBytes (15000 CD-ROMs)
• 756 data takes, mapped surface: 120 x 106 km2
Areas of X-SAR Application• 115 Principal investigators
(AO)
• 1,000+ requests during andafter the mission
• Accuracy: horizontal 20m / vertical 6m (15m absolute)
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47Institut für Hochfrequenztechnk und Radar
Geometric Stability
excellent baseline stability:
4 ηinc=54.50 average +-0.20
4 data from shuttle nav. system
excellent antenna co-alignment:
4 Doppler differences ca. 50 Hz between both channels
small, coupled oscillations of shuttle and boom, will be compensated
44.55
44.60
44.65
0 5 10 15 20time [s]
0.10
0.14
0.18
0.22
0.26
0 5 10 15 20
time [s]44.70
Boom tip [m]
Shuttle attitude [deg]Boom tip
Shuttle roll attitude
Eineder, M. 2000
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48Institut für Hochfrequenztechnk und RadarsystemeQue
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Results (II)
SRTM/X-SAR color coded interferogram of the peninsula of Hokkaido/Japan, MET 5/07:55:00
Eineder, M. 2000
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49Institut für Hochfrequenztechnk und Radar
Throughput
11 day mission
4 69 data takes have been received and analyzed during mission
4 72 Gigabytes of data
4 99 interferograms generated
4 45 DEMs
InSAR processing of a 45 km x 170 km takes 1 hour
4 some variation depending on the phase unwrapping difficulty
4 including automated tie pointing.
processing is done on a 12 CPU SUN E4000
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Receive Signal Phase - Corrections
Antenna 2LNA's
XCB
XDC
RFE
RAE
IFD
Antenna 1
Boom
135MHz
1052MHz
263MHz
WG
Secondary Channel Primary Channel
STALO
1. No beam steering was done during mission -> No correction necessary
5. Due to major temperature variation of XDC there were high phase errors in the receive path-> Phase correction with Cal Tone (max. expected error?)6. Due to temperature variations of the mast cable there were phase errors in the receive path-> Phase correction with Mast Phase HK (max. 9°)(max. expected error for receive signal 330° within a orbit )
3. Cal Tone was in ‘cycling mode’-> Each Cal Tone path has a different Cal Tone Offset (max. expected difference 360°)4. Cal Tone Level was following IFD gain (XDC/RAE Cal Tone Att.)-> Correction of the phase jumps for different XDC/RAE Cal Tone Att. Settings with Cal Tone Att. Characterization data. (max. expected phase jump 60°)
2. Variation of XOA coax cable temperature 5°C/orbit -> Phase correction with Cal Tone ( max. expected error 0.2°)
7. Different gain settings (70 dB … 80 dB) was used-> Correction of the phase jumps for different Gain Att. Settings with Gain Att. characterization data.
(max. expected phase jump 60°)8. Due to a low temperature variation (about 2°C) of the shuttle cold plates there were minor phase errors in the receive path (RAE, IFD,RFE)-> Phase correction with Cal Tone ( max. expected error ?)
9. Low temp. variation for Coax Cable with Ref. Signal -> No Correction possible (max. expected error < 0.1°/10 min, for 1052 MHz)
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Interferometric Performance
Coherence
4 desert regions no problems so far
4 water surfaces sometimes decorrelate under calm wind conditions
Coregistration
4 currently better than 0.05 pixelShadow / Layover
4 layover no problem: < 0.06 % in alpine regions
4 shadow problems in alpine regions: ca. 7% of ground surface
Remote Sensing Technology Institute
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52Institut für Hochfrequenztechnk und Radar
SRTM Calibration:measured Height over Ocean
Remote Sensing Technology Institute
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53Institut für Hochfrequenztechnk und RadarsystemeQue
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53Institut für Hochfrequenztechnk und Radar
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54Institut für Hochfrequenztechnk und Radar
Mast Phase and Mast Temperature
-30
-20
-10
0
10
20
30
05. 22:00:00 05. 23:00:00 06. 00:00:00 06. 01:00:00 06. 02:00:00
MET
Tem
p 'M
ast_
58D
'
184,00
186,00
188,00
190,00
192,00
Mas
t Pha
se
at 2
63 M
Hz
Mast_58DMast Phase
Remote Sensing Technology Institute
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Mast motion and antenna alignment
1.4 0.7 0 0.7 1.4
Dynamic mast torsion (pitch axis)= max 0.05º
Dynamic mast deflection (yaw axis)= max 0.02º
Dynamic mast deflection (roll axis)= max 0.1º
0 10 20 30 40 sec
+0,04
0,00
-0,04
Remote Sensing Technology Institute
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56Institut für Hochfrequenztechnk und Radar
Geometric Stability
excellent baseline stability:
4 ηinc=54.50 average +-0.20
4 data from shuttle nav. system
excellent antenna co-alignment:
4 Doppler differences ca. 50 Hz between both channels
small, coupled oscillations of shuttle and boom, will be compensated
44.55
44.60
44.65
0 5 10 15 20time [s]
0.10
0.14
0.18
0.22
0.26
0 5 10 15 20
time [s]44.70
Boom tip [m]
Shuttle attitude [deg]Boom tip
Shuttle roll attitude
Eineder, M. 2000Remote Sensing Technology Institute
Remote Sensing Technology Institute
M. Eineder, 30.11.2001
SRTM Calibration: Mast Oscillation Problem
ca. 160 km
44.60
44. 50
44.40
44.30
shut
tle ro
ll an
gle
0 1400 2800 4200 [Km]
44.20
1. Gravitygradient rotatesinterferometer
to uprightposition
2. At dead band limitshuttle fires thrusters to
return to nominalattitude
3. Shuttleaccelerationcauses mast
oscillations ...
300 meterheight
oscillations!
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Results (I)
SRTM/X-SAR Radar amplitude image of the peninsula of Hokkaido/Japan, MET 5/07:55:00
Eineder, M. 2000Remote Sensing Technology Institute
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59Institut für Hochfrequenztechnk und Radar
Results (III)
SRTM/X-SAR coherence map of the peninsula of Hokkaido/Japan, MET 5/07:55:00
Eineder, M. 2000Remote Sensing Technology Institute
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Results (IV)
SRTM/X-SAR DEM of volcano Komaga-take on Hokkaido/Japan, MET 5/07:55:00
Eineder, M. 2000Remote Sensing Technology Institute
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61Institut für Hochfrequenztechnk und Radar
Phase unwrapping: Komaga-take (1131m)
Moderate topography: Minimum cost flow (MCF) method gives excellent results!
Eineder, M. 2000Remote Sensing Technology Institute