GPS World September 2006 - 4

INNOVATION | RTK Systems SD Wind-up [PRN16, Head-Hall, 06 SEP
2005:248145.8] SD Wind-up [PRN16, Head-Hall, 06 SEP 2005:248186.3] 100 400
Azimuth [deg] Azimuth [deg] 300 95 200 90 100 85 0 0 100 200 300 400 500
600 700 800 900 0 100 200 300 400 500 600 700 800 900 -0.3 0.4 Height [m]
-0.4 Height [m] 0.2 -0.5 0 -0.6 -0.2 -0.7 -0.4 0 100 200 300 400 500 600
700 800 900 0 100 200 300 400 500 600 700 800 900 0.04 0.02 0.02 L1-L2 [m]
0.01 L1-L2 [m] 0 0 -0.02 -0.01 -0.04 -0.02 0 100 200 300 400 500 600 700
800 900 0 100 200 300 400 500 600 700 800 900 Elapsed Time [seconds]
Elapsed Time [seconds] FIGURE 2 Single-differenced phase wind-up
observations using a FIGURE 1 Single-differenced phase wind-up
observations using pair of rotating antennas one static and one rotating
antenna first two rotations, we may see the combined The performance of
the UNB RTK sys- clearly shows the effects of phase wind- effects of three
different error sources includ- tem was very good most of the time during
up. As the vehicle changed its direction ing the residual spin modulation
of the phase the test. However, we found several places about 180 degrees
see the top panel and where the system had problems. In some Figure 5 ,
the phase wind-up observations wind-up, antenna phase-center variation,
and cases, this took place when the vehicle should pick up a half of the
wavelength dif- multipath. In fact, it is the combined effects changed its
direction FIGURE 5 note the ference between L1 and L2 carrier phases. of
several error sources rather than the iso- For PRN 18 in Figure 7, we see
this change lated effects of the phase wind-up that can gaps in the
solutions. So we began to inves- of 2.5 centimeters. On the other hand,
compromise an RTK system in reality. We tigate what caused the system
problems. We we saw an additional change of around 1

GPS World September 2006

Table of Contents for the Digital Edition of GPS World September 2006

GPS World September 2006 - 1
GPS World September 2006 - 2
GPS World September 2006 - 3
GPS World September 2006 - 4
GPS World September 2006 - 5
GPS World September 2006 - 6
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