The Tracking, Occultation and Ranging (TOR) instrument onboard TerraSAR-X and on TanDEM-X. - Markus Rothacher; Byron D. Tapley; Cristoph Reigber; Rolf König; Carsten Falck; Ludwig Grunwaldt; Wolfgang Koehler; Franz-Heinrich Massmann; Grzegorz Michalak (IGARSS, 2007)