Sar multitemporal speckle nosie reduction


I need to generate radiometrically terrain corrected images and then apply speckle filter. I have got three stripmap CosmoSkyMed images. I used 1) Radar → Radimetric -->Calibrate to extract sigma 0, then 2) Radar -->Radiometric → Radiometric Terrain Flattening and then 3) Radar -->Terrain Correction → Range-Doppler terrain correction for each image separately. Now, I want to do speckle filtering and I know that for the multitemporal method I need the co-registered data. Could you please advice me how to include the coregistration in the pre-processing steps mentioned above? I tested Radar -->Coregistration with different inputs including the calibrated data extracted from step 1., but non of them worked.