Bernese GPS Software Version 5.0 - Bernese GNSS Software

nSat : the number of satellites, and
6.6 Screening of Post-Fit Residuals
nDel : the number of observation pieces rejected based on the thresholds specified in
options “DETECT LARGE RESIDUALS” in panel “RESRMS 2: Options” and added
to the edit information file.
The units for the residuals in program RESRMS is in general millimeters. The residuals for
code measurements are re-scaled with respect to the residuals of phase measurements using
a factor of 100 (specified in the file ${X}/GEN/CONST.), i.e., the units for code residuals are
decimeters.
All other weights applied in the parameter estimation process when computing the residuals
(e.g., “Elevation-dependent weighting”, or “Station sigma factors” in program GPSEST) cannot be
taken into account in program RESRMS. It is strongly recommended to save normalized
residuals in GPSEST to assure a reliable and homogeneous outlier detection by RESRMS.
Normalized residuals are defined as r norm = r/σr where r is the real residual and σr is
the a priori (NORM APR) or the a posteriori (NORMALIZED for (option “Type of computed
residuals” in panel “GPSEST 3.1: General Options 1”) RMS of the residual (see Section 7.4.4). In
contrast to real residuals, normalized residuals are always converted to one-way L1 carrier
phase residuals.
One of the major purposes of the program RESRMS is the screening of post-fit residuals.
The residual file from a GPSEST solution is analyzed for outliers and an edit information
file (description in Section 22.10.7) is written. Using this file program SATMRK (description
in Section 6.7.1) can mark the corresponding measurements in the observation files.
These steps are highly recommended when processing baseline files and are mandatory when
processing zero-difference observation files. When the observation files are preprocessed by
the program RNXSMT (zero-difference case) the screening of the post-fit residuals should
be done iteratively with lowering the outlier detection thresholds (option “DETECT LARGE
RESIDUALS”).
Station Observation Sigma Factors
For each individual station a measurement noise may be computed from the residuals of
their observations. Station observation sigma factors are then derived from this measurement
noise. The conversion of measurement noise to sigma factors may be defined by the
options “STATION OBSERVATION SIGMA FACTORS” in panel “RESRMS 3: Residual Statistics
and Sigma Factors”. The station sigma factors may be stored in a file which is described in
Section 22.8.14.
The purpose of these station observation sigma factors is the following: As the noise of
original code observations (not smoothed by program RNXSMT) may differ significantly for
different receivers the sigma factors may be used for weighting the code observations in the
parameter estimation or for rescaling the outlier rejection thresholds in program CODSPP.
Station sigma factors are not necessary when processing phase observations.
A file containing normalized residuals which were generated in GPSEST using a station
observation sigma file already applied cannot be use to generate a new station sigma file.
Bernese GPS Software Version 5.0 Page 133