Principles of Modern Radar - Volume 2 1891121537

340 CHAPTER 8 Interferometric SAR and Coherent Exploitationβ̂δhδR˜ x , ˜ yφφ a , φ bφ abφ G ,φ R ,φ ρφabFE˜φ, ˜φ a , ˜φ b , ˜φ ab˜φ refab˜φ difab , ˆφ difabγγ noise , γ spatial , γ temporalλσ hξψψ 0ψ 1ψ Bσ φabσ 2ˆφ abσ 2̂ |γ |BB tB tcB ⊥B c⊥dDD t⊥hĥĥ difHI abpPP 1 ,P 0sensor tilt angle, relative to horizontalestimated change in heightdifference in range to two sensorsx- and y-dimension gradients of the interferometric phasedifferencephasephase shift at receivers a and b, respectivelyinterferometric phase differencephase shift due to radar receiver transfer function, propagationrange, and scatterer complex reflectivity, respectivelyflat-earth interferometric phase differencewrapped values of phases φ,φ a ,φ b ,φ abwrapped reference interferometric phase differencewrapped, estimated differential interferometric phasedifferencesobjective function for phase unwrappingcoherencecoherence due to noise, baseline decorrelation, and temporaldecorrelation, respectivelywavelengthstandard deviation of hpeak-to-RMS ratiogeneral depression angle relative to horizontaldepression angle to foreshortened scatterer, relative tohorizontaldepression angle to elevated scatterer, relative to horizontalangular baseline (radians)standard deviation of interferometric phase differencevariance of estimated interferometric phase differencevariance of estimated coherence magnitudesensor baseline separationtemporal baselinedecorrelation time of temporal baselinesensor baseline projected perpendicular to the line of sightcritical perpendicular baselinedriving function for Ghiglia-Romero phase unwrappingalgorithmtwo-dimensional discrete cosine transform of dtomographic aperture projected orthogonal to the line of sightscatterer elevationestimated elevationestimated differential elevationplatform height above ground levelinterferogramsingle- versus dual-transmitter scale factor for interferometricphase differenceerror power in phase unwrapping objective functionactual and foreshortened scatterer locations