ALOS-1 Interferometry Issue

Hi All,

I’m trying to perform ALOS-1 PALSAR repeat-pass InSAR. I have 1 master, and two slaves, with 45 / 90 days temporal baseline and ~ 0.9 km / ~2.2 km spatial baseline, respectively. The InSAR pair with the shorter baselines works, but the InSAR pair with the larger baselines fails to go through the co-registration step. I am doing de-skeweing as a first step on all three complex images. The co-registration for the 2nd pair just returns blank master and slave output bands. Is it due to too large baseline, even though literature says critical baseline for ALOS can be as large as 5-6 km? Anyone has any experience with this issue, or any input?

Many thanks,