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Bernese GPS Software Version 5.0 - Bernese GNSS Software

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16.4 Estimation of Phase Center Corrections<br />

Figure 16.4: Program input panels for the determination of the receiver antenna phase<br />

center variation in program <strong>GPS</strong>EST.<br />

RECEIVER-DEPENDENT: One (common) receiver antenna offset is estimated for every combination<br />

of receiver type and antenna type. In a separate selection list the reference<br />

antenna (or a group of reference antennas) has to be specified.<br />

INDIVIDUAL: You get a selection list where you can select individual antennas (i.e., including<br />

the antenna serial number) for the receiver antenna offset estimation.<br />

MANUAL: In an additional panel you may specify the parameter setups for each antenna<br />

or antenna type in detail.<br />

You can estimate not more than N − 1 offsets if you have N different receivers because you<br />

can only relatively calibrate receiver antennas in a field campaign.<br />

In the panel “<strong>GPS</strong>EST 6.2.1: Receiver Antenna PCV Patterns 1” (see Figure 16.4) the parameters<br />

to be estimated are selected for the elevation and azimuth dependent part of the receiver<br />

antenna phase center variation model. To estimate azimuth independent variations you have<br />

to set the “Azimuth increment” to 360 degrees for the polygon model respectively the “Order m”<br />

to 0 for the spherical harmonics representation. The selection of the antennas is analogous<br />

to the estimation of the receiver antenna offsets.<br />

If no reference antenna is specified, an a priori sigma for each parameter is required in order<br />

to prevent the normal equation system from becoming singular. If a reference antenna is<br />

specified, in general no a priori sigma is required, because the singular (0,0) term is not<br />

estimated in the spherical harmonics model and a zero mean condition is imposed on all<br />

grid points for the piece-wise linear model.<br />

Because of the correlations it makes no sense to estimate receiver antenna offsets and azimuth<br />

and elevation dependent variations together in one program run. The parameters<br />

for the receiver antenna models are not yet supported by ADDNEQ2 and cannot be stored<br />

in normal equation files. As a consequence, all available sessions of a calibration campaign<br />

<strong>Bernese</strong> <strong>GPS</strong> <strong>Software</strong> <strong>Version</strong> <strong>5.0</strong> Page 343

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