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PCV Calibration & Results of AOAD/M_T

Details, Accuracy, Precision

The Allen Osborne Associates Dorne Margolin Model T (AOAD/M_T), serial number (SN) 404 has been extensively calibrated using the automated real-time absolute PCV field calibration method by IfE and Geo++®

There were in total 42 calibrations, which were combined using the complete variance-covariance matrix of the individual results for a combined PCV estimation.

The calibrations differ by location, constellation (robot, satellites, weather, ...) and date. Spherical harmonics of degree 8 and order 5 were used for all real-time calibrations and for the final PCV model.

The absolute PCV are given in meter using the sign convention of the Geo++ antenna file format, which is opposite to the IGS/NGS. The graphics show the L1 and L2 PCV after removing the offset

OFFSETS L1=+0.00060 -0.00046 +0.09124
OFFSETS L2=-0.00010 -0.00062 +0.12006

(north, east, height in [m]).

The PCV vary for L1 over a range of approximately 20 mm and for L2 over 14 mm (click on the images - L1, left / L2, right - for a high resolution jpg).

Phase Center Variations GPS L1
Phase Center Variations GPS L2

Standard Deviation

The standard deviation is generally homogeneous for all azimuths and is in the order of 0.3-0.5 mm for most of the elevation ranges with a slight degradation to 1-2 mm for elevations below 5 deg. The large number of combined calibrations of the AOAD/M_T gives a too optimistic standard deviation well below 0.1 mm, but with the same elevation dependent degradation (click on the images - L1, left / L2, right - for a high resolution jpg). Nevertheless, the overall standard deviation of the 42 combined calibrations is at the 0.2 mm level.

Standard deviation of Phase Center Variations GPS L1
Standard deviation of Phase Center Variations GPS L2

Azimuthal Variations

Azimuthal PCV L0 (offset and elevation dependent terms removed)

The azimuthal variations in the PCV are generally below 1 mm for the AOAD/M_T. However, the effect in L0 (ionospheric free signal) reaches values of 1 mm, even for the elevation range from 90 to 10 deg (click on the image for a high resolution jpg). At lower elevations, the azimuthal variations are even higher.

Azimuthal PCV L0 (offset and elevation dependent terms removed).

Repeatability

The repeatability is derived from independent calibrations at two sites (identical antenna). The repeatability gives values between 0.5 to 1 mm in the elevation range from 90 to 10 deg. For the elevation range from 10 to 0 deg the repeatability shows higher differences above 1 mm, which can individually amount to some mm at the horizon. However, the mean repeatability is generally at the 0.5 to 1 mm level.

The following graphics are the difference in PCV from one calibration done by IfE and one by Geo++®. The robots, the locations and the general conditions were different. The calibrations were selected by chance. For an operational calibration always two calibrations are combined, which
gives a better repeatability than presented here. For the repeatability, the PCV were reduced to the same height offset (combined solution) with no horizontal offsets (included in the PCV).

(Click on the images - L1, left / L2, right - for a high resolution jpg)

Phase Center Variations GPS L1
Phase Center Variations GPS L2

Individual Sets of PCV Calibrations

The following survey indicates the individual calibrations, which were input to the combined solution of absolute PCV for the AOAD/M_T, SN 404. The number of epochs differ due to different options in the automated guidance of the real-time calibrations. Listed are an internal counter, date, local time, number of epochs and the standard deviation of weight unit of the simulataneous real-time processing of both GPS frequencies for the AOAD/M_T GPS antenna.

IfE Calibrations of AOAD/M_T, SN 404

  4  Date: 2000-04-12 10:27:15 Epochs: 13347 s0: 0.662
  5  Date: 2000-04-13 08:28:51 Epochs: 11463 s0: 0.670
  6  Date: 2000-04-14 07:43:06 Epochs: 16068 s0: 0.712
  7  Date: 2000-04-15 14:39:25 Epochs: 10697 s0: 0.640
  8  Date: 2000-04-17 12:34:08 Epochs: 11847 s0: 0.611
  9  Date: 2000-05-22 14:21:46 Epochs:  6987 s0: 0.702

Geo++® Calibrations of AOAD/M_T, SN 404

  1  Date: 2000-04-29 10:26:10 Epochs: 11957 s0: 0.743
  2  Date: 2000-04-29 15:03:43 Epochs:  6311 s0: 0.850
  3  Date: 2000-04-29 22:15:24 Epochs: 11239 s0: 0.800
  5  Date: 2000-04-30 20:12:03 Epochs: 12937 s0: 0.697
  6  Date: 2000-05-01 01:02:46 Epochs:  6465 s0: 0.745
  8  Date: 2000-05-01 13:53:15 Epochs: 15594 s0: 0.672
  9  Date: 2000-05-02 03:55:00 Epochs:  6655 s0: 0.854
 10  Date: 2000-05-23 12:56:17 Epochs: 11711 s0: 0.732
 11  Date: 2000-05-23 16:55:27 Epochs:  7433 s0: 0.888
 12  Date: 2000-05-23 19:20:23 Epochs:  7103 s0: 0.919
 13  Date: 2000-05-24 11:34:19 Epochs:  7267 s0: 0.674
 14  Date: 2000-05-24 13:57:43 Epochs:  6779 s0: 0.830
 15  Date: 2000-05-24 17:36:01 Epochs:  5721 s0: 1.013
 16  Date: 2000-05-24 19:51:57 Epochs:  5829 s0: 0.612
 17  Date: 2000-05-24 21:55:43 Epochs:  5235 s0: 0.600
 18  Date: 2000-05-24 23:42:41 Epochs:  5573 s0: 0.675
 19  Date: 2000-05-25 01:34:12 Epochs:  6120 s0: 0.915
 21  Date: 2000-05-25 13:04:55 Epochs:  7127 s0: 0.651
 22  Date: 2000-05-25 15:32:38 Epochs:  3283 s0: 0.861
 23  Date: 2000-05-25 18:01:14 Epochs: 10867 s0: 0.724
 24  Date: 2000-05-25 22:02:56 Epochs:  6575 s0: 0.636
 25  Date: 2000-05-26 00:25:17 Epochs:  6347 s0: 0.750
 26  Date: 2000-05-26 10:18:44 Epochs:  6145 s0: 0.792
 27  Date: 2000-05-26 12:24:13 Epochs:  5599 s0: 0.641
 28  Date: 2000-05-26 14:17:33 Epochs:  7711 s0: 0.807
 29  Date: 2000-05-26 16:50:23 Epochs:  5879 s0: 0.826
 30  Date: 2000-05-26 18:45:02 Epochs:  6151 s0: 0.721
 31  Date: 2000-05-26 20:58:25 Epochs:  7193 s0: 0.597
 32  Date: 2000-05-26 23:32:22 Epochs:  6865 s0: 0.728
 33  Date: 2000-05-27 10:46:42 Epochs: 11933 s0: 0.635
 34  Date: 2000-05-27 15:15:16 Epochs:  6977 s0: 0.886
 35  Date: 2000-05-27 17:39:17 Epochs:  7159 s0: 0.836
 36  Date: 2000-05-27 20:07:39 Epochs:  6399 s0: 0.655
 37  Date: 2000-05-27 22:25:35 Epochs:  6845 s0: 0.663
 38  Date: 2000-05-28 00:42:42 Epochs:  8019 s0: 0.809
 39  Date: 2000-05-28 03:24:06 Epochs:  6217 s0: 0.861