ALOS Data Users Handbook

Section 3 Outline of ALOS Satellite SystemPRISMBackward Telescope UnitForward Telescope UnitNadir Telescope UnitElectrical UnitAsymmetric CacheBuffer / Editor BUpwelling RadiationOpticsOpticsThermalINTDetectorDetectorModuleDriveElectronicsRadiometer StructurePre-ampElectronicsWireHarnessAnalog Signal ProcessorPost-ampElectronicsController/TimeGeneratorPower SupplyPS Electronics BPS Electronics AA/DConvSTRSTRWireHarnessAsymmetric CacheBuffer / Editor ADigital SignalProcessorControllerPower SupplyThermalINTSTRALOS SystemOptical BenchThermal Control UnitThermal TC Electronics AINTTC Electronics BWire HarnessFigure 3.2-2 PRISM Block DiagramMain characteristics of PRISM are shown in Table 3.2-2 and the main operation modes are given by Table 3.2-3.Table 3.2-2 PRISM Main CharacteristicsItem Forward Nadir Backward NoteObservation Band0.52 to 0.77 μmIFOV3.61 μradFOV5.8 deg. – 70 km swath2.9 deg. 2.63 deg. 35 km swathScan Cycle0.37msPointing Angle ± 1.5 deg. ± 1.36 deg. For triplet observationMTF > 0.2 Including MTF degradation along trackby spacecraft flightS/N > 70Gain Setting4 stepsAD Bit 8Data Rate < 960 Mbps (320 Mbps/telescope) Before compressionAngle from nadir ± 23.8 deg. (for forward and backward) Along trackTable 3.2-3 PRISM Operation ModesMode Content RemarksObservationNominal mode1 Nadir / Forward / Backward views simultaneous observation(35km swath of each view)2 Nadir 70km + Backward 35km simultaneous observation3 Nadir 70km observation1Electrical Calibration ModeCondition is the same as(Get Electronics calibration data after the detector)Observation Mode 1Calibration Blackbody Calibration Mode2 (Measure offset level of image signal when zero inputsignal)ditto3-8