Center for Mapping
Zero Baseline Test Results
The results from several one-hour tests, each one
corresponding to two pairs of receivers tested simultaneously are presented in
Figure 1. The residual plots refer to a high satellite; for all types of
receivers the low satellites display residuals larger by 25-50%, as compared to
the ones presented in Figure 1. Due to the loose splitter connection, data on
Trimble 4000SSI were lost; also, due to the incorrect set-up, the Z-12
collected data at a 20-s interval as opposed to a 1-s for the rest of the
receivers. The zero baseline summary statistics, based on
all the tests are presented in Table 2.
Figure 1. L1 phase residuals on zero baseline for PRN 29 (high satellite), first row: Topcon (JPS) Legacy (left) and Trimble 4000SSE (right) with LegAnt antenna (GPS week 1077); second row: Ashtech Z-12 (left), and Leica 9500 (right) with LegAnt antenna (GPS week 1078); third row: Topcon (JPS) Legacy (left) and Trimble 4700 (right) with LegAnt antenna (GPS week 1082); fourth row: for PRN 30 (high satellite), Topcon (JPS) Legacy (left) and Trimble 4700 (right) with Trimble microcentered antenna (GPS week 1082);
|
Receiver type |
Mean residual[cm] |
Stand. Dev. [cm] |
Min residual[cm] |
Max residual[cm] |
|
Mean residual [cm] |
Stand. Dev. [cm] |
Min residual [cm] |
Max residual [cm] |
|
Leica 9500 |
0.00 |
0.06 |
-0.17 |
0.18 |
0.00 |
0.05 |
-0.17 |
0.15 |
|
|
Trimble 4000SSE |
0.00 |
0.06 |
-0.20 |
0.21 |
0.00 |
0.05 |
-0.20 |
0.20 |
|
|
Trimble 4700 |
0.00 0.00* |
0.22 0.19* |
-0.74 -0.61* |
0.71 0.63* |
0.00 0.00* |
0.19 0.18* |
-0.63 -0.57* |
0.66 0.61* |
|
|
Topcon Legacy |
0.00 -0.01 0.00 0.00* |
0.12 0.15 0.09 0.12* |
-0.39 -0.38 -0.32 -0.36* |
0.39 0.39 0.33 0.36* |
0.01 0.00 0.00 0.00* |
0.09 0.09 0.05 0.08* |
-0.39 -0.35 -0.18 -0.31* |
0.39 0.38 0.19 0.36* |
|
|
Ashtech Z-12 |
0.00 0.00 |
0.07 0.06 |
-0.19 -0.14 |
0.17 0.14 |
-0.01 0.00 |
0.05 0.04 |
-0.13 -0.10 |
0.15 0.12 |
Table 2. Zero baselines with LegAnt antenna, low satellite (left) and high satellite (right) – survey statistics (* refers to the test with a microcentered antenna). Results for the receivers tested multiple times are included.
An example of differences between receivers in terms
of their capability of maintaining lock to the satellites is presented in
Figure 2, illustrating comparison between Legacy and 4000SSE. It can be
observed from Figure 2 that both receivers tracked the same satellites, but
Legacy maintained continuous lock to the satellites in view, while 4000SSE
experienced some minor losses on L2 for PRN 6, 11 and 21. On the other hand,
the example plot of single difference residuals from both receivers (Figure 1)
indicate that 4000SSE provides residual bounded within 1 mm, with occasional
jumps to about 2-mm level, while Legacy’s residuals oscillate within 1.5 to 2
mm. There were no other differences in terms of tracking capabilities observed
among other receivers involved in the zero baseline tests.
Figure 2. Satellite L1/L2 phase tracking on zero baseline, Topcon (JPS) Legacy
(left), and Trimble 4000SSE (right) with LegAnt antenna (GPS week 1077).