3.1 Experimental Environment and Positioning Data Processing
The purpose of the experiment is to collect the sample data of single-point positioning
and differential positioning. The experimental equipment includes four sets of BDS
reference receivers and antennas, one data processor, one set of very high-frequency
data broadcast (VDB) transmitter and antenna, one set of BDS test receiver and antenna
and one test computer. Some equipment is shown in Fig. 2.
Four reference receiver antennas are erected at four calibrated corners on the top
floor, respectively, and the test receiver antenna is placed at a calibrated measuring
point. Data processor uses BDS data of four reference receivers to calculate differential
correction. Test computer realizes single-point positioning and differential positioning
by applying correction in positioning calculation. The schematic diagram of the whole
experimental device is shown in Fig. 3. The actual position coordinates of the reference
receiver antennas and the test receiver antenna are shown in Table 1.
The calculating period of the test computer is 1 s and 20,000 sample data expressed
in WGS-84 rectangular coordinate system are collected according to the two methods
of single-point positioning and differential positioning, respectively. Positioning error
ðDx; Dy; DzÞ which includes the horizontal positioning error Dd and the height positioning error Dh is the difference between the calculated value and the true value of the
measured point. The positioning error vector in station-origin coordinate system
ðDe; Dn; DuÞ can be obtained by using the transformation Formula (3):
De
Dn
Du
2
6
4
3
7
5 ¼
À sin k
cos k
0
sin / cos k À sin / sin k cos /
cos / cos k cos / sin k sin /
2
4
3
5
Dx
Dy
Dz
2
6
4
3
7
5
ð3Þ
De; Dn; Du are eastward error, northward error, upward error, respectively. k; / is
the longitude and latitude of the measured point. Thus, we can deduce the horizontal
Fig. 2. Some experimental equipment
Analysis and Experimental Research on Data Characteristics …
39
The purpose of the experiment is to collect the sample data of single-point positioning
and differential positioning. The experimental equipment includes four sets of BDS
reference receivers and antennas, one data processor, one set of very high-frequency
data broadcast (VDB) transmitter and antenna, one set of BDS test receiver and antenna
and one test computer. Some equipment is shown in Fig. 2.
Four reference receiver antennas are erected at four calibrated corners on the top
floor, respectively, and the test receiver antenna is placed at a calibrated measuring
point. Data processor uses BDS data of four reference receivers to calculate differential
correction. Test computer realizes single-point positioning and differential positioning
by applying correction in positioning calculation. The schematic diagram of the whole
experimental device is shown in Fig. 3. The actual position coordinates of the reference
receiver antennas and the test receiver antenna are shown in Table 1.
The calculating period of the test computer is 1 s and 20,000 sample data expressed
in WGS-84 rectangular coordinate system are collected according to the two methods
of single-point positioning and differential positioning, respectively. Positioning error
ðDx; Dy; DzÞ which includes the horizontal positioning error Dd and the height positioning error Dh is the difference between the calculated value and the true value of the
measured point. The positioning error vector in station-origin coordinate system
ðDe; Dn; DuÞ can be obtained by using the transformation Formula (3):
De
Dn
Du
2
6
4
3
7
5 ¼
À sin k
cos k
0
sin / cos k À sin / sin k cos /
cos / cos k cos / sin k sin /
2
4
3
5
Dx
Dy
Dz
2
6
4
3
7
5
ð3Þ
De; Dn; Du are eastward error, northward error, upward error, respectively. k; / is
the longitude and latitude of the measured point. Thus, we can deduce the horizontal
Fig. 2. Some experimental equipment
Analysis and Experimental Research on Data Characteristics …
39