A fast multi-baseline and multi-frequency band phase-unwrapping algorithm

•The 2D FFTs of gradient functions are derived, see Eqs. (11) and (12).•Eq. (3) is derived to satisfy the irrotational-field boundary condition.•The computational complexity of the novel method is estimated and compared.•Real and simulated data are processed to verify the novel method.•The novel method is about three times faster than the time-domain method.

Multi-baseline and multi-frequency band can improve the performance of phase unwrapping. This paper, taking the multi-baseline InSAR (interferometric synthetic aperture radar) system as an example, proposes a fast method for multiple-baseline and multi-frequency band phase unwrapping in the frequency domain. The basic idea is to perform a least-squares minimization of the differences between the estimated and absolute phase gradients on all interferograms simultaneously, which are all in the frequency domain. Results on real and simulated data show that the frequency-domain method yields results similar to those of the time-domain method while improving efficiency by avoiding mirroring operations.