For interferometric SAR, the baseline requirements change depending on the specific application. For differential interferometry, the objective is to observe surface movements disregarding the topography. With baseline equal to zero (<5m), the topography information in the interferogram will disappear. Such short baseline are therefore wanted in applications such as glacier movement studies.
For normal interferometry on the contrary, it is the topography that is sought in the process. Signal processing constraints such as noise and the correlation criterion lead to optimal results with baseline ranging from 150 to 300 m, but results can be obtained with baseline up to 600 m.
In order to increase significantly the number of Interferometric orbit pairs, the Ice Phase shall be divided in sub-phases, for which the orbit drifts shall restart from the same points.
Ground track maintenance at the Poles, Out-Of-Plane manoeuvres
The Ice Phase is divided in 2 sub-phases, separated by an Out-Of-Plane manoeuvre (OCM). The objective is to repeat as much as possible the inclination drift. Each sub-phase duration should be around 7 weeks.
Ground track maintenance at the Equator, In-Plane manoeuvres
During each 7 weeks sub-plane, the ground track will be maintained at the Equator in such a way that only one In-Plane manouvre is performed in the middle of each sub-phase. The ground track dead band at the Equator shall then be computed by ESOC in order to fulfil the manoeuvre spacing requirement, and should be in any case lower than +-1 Km. A third In-Plane manoeuvre is necessary at the same time as the Out-Of-Plane Manoeuvre.
Orbit number characteristics
ABS_ORB_NUM = REL_ORB_NUM + CYCLE_NUM*43 + 8341
CYCLE_NUM = INT( ( ABS_ORB_NUM - 8342)/43 )
REL_ORB_NUM= ABS_ORB_NUM - 8341 - CYCLE_NUM *43
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Remko Scharroo, firstname.lastname@example.org