change of both PS and DS targets. SqueeSAR technology [11] is one example of the PSDS technique. The PL technique is applied first to all the ()/NN 12interferograms available from N images. It jointly exploits these interferograms to squeeze the best estimates of N 1interferometric phases. Once the estimate of the N 1- linked phases has been produced, the second step is necessary to remove the signal decorrelations and estimate the parameters of interest, such as the elevation error and constant velocity, similar to the PS interferometry