Download SMOS L1 Processor Algorithm Theoretical Baseline Definition

SMOS L1 Processor
Algorithm
Theoretical Baseline
Code
:
SO-DS-DME-L1PP-0011
Date
:
29/10/10
Issue
:
2.10
Page
:
34 of 89
VkjH ,V = TsysH k,V TsysH ,jV M kjH ,V
Eq. 67
and apply the in-phase and amplitude error corrections as well as removing the offsets computed
previously.
The visibilities offsets are corrected with the switch S-parameters, retrieved using the physical
temperature at calibration time:
VkjUH ,V = VkjUC
S LCk S LCj
S LH ,Vk S LH ,Vj η H ,Vkη H ,Vj
Eq. 68
The final equation will thus be:
H ,V
V
VˆkjH ,V = kjH ,V − akjVˆkjUH ,V
g kj
where
Eq. 69
akj is a coefficient to adjust the influence of the visibilities offsets in the final calibrated
visibility. This coefficient is defined as an integer number (0, 1 or 2) indicating if offset correction is
needed for baseline kj.
Additionally, as discovered by ESTEC during November 2007, the offset correction for baselines
involving NIR-LICEF needs to be corrected with a factor 2, due to the different integration time in
which the NIR-LICEF are providing correlations (the rest of the time it operates as a NIR).
During IVT campaign, it was seen that offset correction is only required for baselines sharing the same
Local Oscillator, so for the current time there shall be three configurable processing options:
No offset correction ( akj = 0 for all baselines)
Offset correction ( akj = 1 for all LICEF baselines, and akj = 2 for all NIR-LICEF baselines)
Local Oscillator Offset Correction ( akj = 1 only for LICEF baselines sharing the same Local
Oscillator, i.e. the LICEF for those baselines are linked to the same CMN, and akj = 2 only for NIRLICEF baselines sharing the same Local Oscillator)
3.1.7.2. Redundant Space Calibration
This method is based on the fact that there are redundant baselines measured that should be measuring
the same value, in case this is not true, it can be attributed to separable amplitude and phase errors
associated to each receiving chain.
As this method is very sensitive to non-separable errors, in SEPS it has only been applied to calibrate
non-normalised visibilities to correct for error terms associated to the path between the antenna and the
input switch, that is, for all the antennae along the arms.
The set of equations for this purpose is expressed in phase and amplitude as [RD.18]:
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