a good start is the work of Andy Hooper:
- http://sismologia.ist.utl.pt/files/Hooper_2004.pdf
- http://eoscience.esa.int/landtraining2017/files/materials/D4T1a_P.pdf
- https://web.stanford.edu/group/radar/people/Hooper_Thesis.pdf
But we also have an own category about this in our forum: StaMPS - Detailed instructions - #2 by ABraun