****************************************************************************** DORIS Electronic Mail Mon Aug 31 16:46:36 WETDST 1998 Message Number 0051 ****************************************************************************** Author: Murielle COSTES, Jean-Paul BERTHIAS Subject: 10 days of missing DORIS SPOT2 dataO Dear Colleagues, DORIS performs measurements at 2 frequencies, around 400 MHz and 2 GHz. Any other system that transmits in these bands will interfere with the signal and cause loss of data. In order to monitor the power radiated in these bands, and thus detect potential sources of jamming, the DORIS instrument has the capability to function in a listening only mode (known as "jamming" measurement mode). To validate the "jamming" measurements made by the DORIS instrument on SPOT4 during its commissioning phase, the DORIS instrument on SPOT2 was turned into the "jamming" measurement mode in early June for two SPOT sub-cycles (about 5 days each). The exact schedule of this campaign was as follows: - May 30 through June 3, 1998 : monitoring of the 400 MHz band - June 4 through June 8, 1998 : monitoring of the 2 GHz band - return to nominal operation on June 8 at 23:51 UTC. When operating in the "jamming" measurement mode no Doppler measurements can be made. Thus, no DORIS data are available for SPOT2 during these 10 days. However, the DORIS instrument on SPOT4 was operational at that time, and data were acquired. They will be released as soon as they can be Validated and properly formatted (probably around end of September / beginning of October). A report comparing "jamming" measurements made by SPOT4 and SPOT2 will be available by mid-september. This input will be used at system level. Murielle Costes, DORIS system Manager, CNES Jean-Paul Berthias, Precise Orbit Determination Group Manager [Mailed From: Pascal Willis ]