The ONERA RAMSES system is a flexible SAR system in constant evolution, developed mainly as a test bench for new technologies and to provide specific data for TDRI (Target Detection, Recognition and Identification) algorithm evaluation. It is flown on a Transall C160 platform operated by the CEV (Centre d'Essais en Vol). This paper gives an overview of the latest upgrading to acquire large data set without on board deramp-on-receive mode and then present the acquisition campaign at X band for very high resolution single pass interferometric multi-baseline mode. The multi- baseline mode used is a ping-pong mode where four antennas are used. The goal of this campaign was to acquire interferometric data in very high resolution mode, better than 0.3 m along slant range axis with a large slant range swath of 2400 m.