Hello Tomoji, "Tomoji Takasu" <[email protected]> writes: > Large multipath might much degrades solutions. I recommend > you had better use good antennas.
I see. I connected two cheap external antennas to the receivers and performed the experiment again in the same place. I converted the resulting files http://iki.fi/lindi/gps/experiment/2/neo1.ubx http://iki.fi/lindi/gps/experiment/2/neo2.ubx to RINEX using $ rtklib-convbin neo1.ubx $ rtklib-convbin neo2.ubx and then went on to try different rtklib modes. Single mode (-p 0) ================== I used $ rtklib-rnx2rtkp -p 0 neo1.obs neo1.nav > neo1.pos $ rtklib-rnx2rtkp -p 0 neo2.obs neo2.nav > neo2.pos to calculate positions of individual receivers separately. From http://iki.fi/lindi/gps/experiment/2/p0-neo1-scatter.png http://iki.fi/lindi/gps/experiment/2/p0-neo2-scatter.png you can see that the radius of scatter is around 0.00005 degrees. DGPS mode (-p 1) ================ I used $ rtklib-rnx2rtkp -x 2 -p 1 -l 60.217480929 24.393206102 71.2617 neo1.obs neo2.obs neo2.nav > p1-neo1.pos to calculate the position of neo1 by using neo2 as base. As you can see in http://iki.fi/lindi/gps/experiment/2/p1-neo1-scatter.png the resulting scatter is still around 0.00005 degrees. Is this because DGPS only helps with systematic error that is the same for both receivers? In the log file Q==4 so I assume that DGPS itself worked. The trace file contains segments like $ sed -n 2000,2020p rnx2rtkp.trace 2 valpos : validation failed (08:40:49.99 nv=6 np=3 vv=54.85 cs=16.30) 2 valpos : large residual (08:40:50.99 sat=8-26 L1 v=-4.932 sig=0.904) 2 valpos : validation failed (08:40:50.99 nv=6 np=3 vv=53.01 cs=16.30) 2 valpos : large residual (08:40:51.99 sat=8-26 L1 v=-4.889 sig=0.904) 2 valpos : validation failed (08:40:51.99 nv=6 np=3 vv=53.64 cs=16.30) 2 valpos : large residual (08:40:52.99 sat=8-26 L1 v=-3.779 sig=0.904) 2 valpos : validation failed (08:40:52.99 nv=6 np=3 vv=34.25 cs=16.30) 2 valpos : validation failed (08:40:53.99 nv=6 np=3 vv=31.12 cs=16.30) 2 valpos : validation failed (08:40:54.99 nv=6 np=3 vv=26.83 cs=16.30) 2 valpos : validation failed (08:40:55.99 nv=6 np=3 vv=25.01 cs=16.30) 2 valpos : validation failed (08:40:56.99 nv=6 np=3 vv=24.13 cs=16.30) 2 valpos : validation failed (08:40:57.99 nv=6 np=3 vv=31.10 cs=16.30) 2 valpos : validation failed (08:40:58.99 nv=6 np=3 vv=42.23 cs=16.30) 2 valpos : validation failed (08:40:59.99 nv=6 np=3 vv=41.14 cs=16.30) 2 valpos : large residual (08:41:00.99 sat=8-26 L1 v=-3.995 sig=0.904) 2 valpos : large residual (08:41:00.99 sat=8-28 L1 v=-3.673 sig=0.917) 2 valpos : validation failed (08:41:00.99 nv=6 np=3 vv=51.05 cs=16.30) 2 valpos : large residual (08:41:01.99 sat=8-26 L1 v=-4.333 sig=0.904) 2 valpos : large residual (08:41:01.99 sat=8-28 L1 v=-3.760 sig=0.917) 2 valpos : validation failed (08:41:01.99 nv=6 np=3 vv=56.15 cs=16.30) 2 valpos : large residual (08:41:02.99 sat=8-26 L1 v=-4.155 sig=0.904) Are these a real problem? Kinematic mode (-p 2) ===================== I first tried $ rtklib-rnx2rtkp -x 2 -p 2 neo1.obs neo2.obs neo2.nav > p2-neo1.pos since this is recommended on page 53 of the manual. However, the resulting file has no positions, why is this? If I add -l and use $ rtklib-rnx2rtkp -p 2 -x 2 -l 60.217480929 24.393206102 71.2617 neo1.obs neo2.obs neo2.nav > p2-neo1.pos then I get positions where the scatter plot http://iki.fi/lindi/gps/experiment/2/p2-neo1-scatter.png still has a radius of around 0.00005 degrees. As you can see with $ grep -c " 1 " p2-neo1.pos 304 $ grep -c " 2 " p2-neo1.pos 10516 most calculated positions have the Q==2 set. According to manual page 60 this should indicate that integer ambiguity is not resolved. Am I still suffering from a poor antenna? The trace file $ sed -n 10000,10020p rnx2rtkp.trace 2 valpos : large residual (09:53:09.00 sat=26-28 L1 v= 4.763 sig=0.891) 2 valpos : validation failed (09:53:09.00 nv=14 np=3 vv=68.98 cs=31.30) 2 valpos : large residual (09:53:10.00 sat=26-9 L1 v= 7.358 sig=1.556) 2 valpos : large residual (09:53:10.00 sat=26-28 L1 v= 4.753 sig=0.891) 2 valpos : validation failed (09:53:10.00 nv=14 np=3 vv=69.81 cs=31.30) 2 valpos : large residual (09:53:11.00 sat=26-9 L1 v= 6.876 sig=1.556) 2 valpos : large residual (09:53:11.00 sat=26-28 L1 v= 4.250 sig=0.891) 2 valpos : validation failed (09:53:11.00 nv=14 np=3 vv=52.83 cs=31.30) 2 valpos : large residual (09:53:12.00 sat=26-9 L1 v= 6.776 sig=1.555) 2 valpos : large residual (09:53:12.00 sat=26-28 L1 v= 4.188 sig=0.891) 2 valpos : validation failed (09:53:12.00 nv=14 np=3 vv=50.52 cs=31.30) 2 valpos : large residual (09:53:13.00 sat=26-9 L1 v= 6.421 sig=1.555) 2 valpos : large residual (09:53:13.00 sat=26-28 L1 v= 4.131 sig=0.891) 2 valpos : validation failed (09:53:13.00 nv=14 np=3 vv=47.92 cs=31.30) 2 valpos : large residual (09:53:14.00 sat=26-28 L1 v= 3.968 sig=0.891) 2 valpos : validation failed (09:53:14.00 nv=14 np=3 vv=42.19 cs=31.30) 2 valpos : large residual (09:53:15.00 sat=26-9 L1 v= 6.403 sig=1.554) 2 valpos : large residual (09:53:15.00 sat=26-28 L1 v= 4.385 sig=0.891) 2 valpos : validation failed (09:53:15.00 nv=14 np=3 vv=52.14 cs=31.30) 2 valpos : large residual (09:53:16.00 sat=26-9 L1 v= 6.232 sig=1.553) 2 valpos : large residual (09:53:16.00 sat=26-28 L1 v= 4.486 sig=0.891) does contain errors but I am not quite sure what they mean. If I use $ rtklib-rnx2rtkp -v 2 -p 2 -x 2 -l 60.217480929 24.393206102 71.2617 neo1.obs neo2.obs neo2.nav > p2-neo1.pos I naturally get more Q==1 positions $ grep -c " 1 " p2-neo1.pos 1084 $ grep -c " 2 " p2-neo1.pos 9736 but the resulting scatter plot still looks the same. -Timo _______________________________________________ This message is sent to you from [email protected] mailing list. Visit http://lists.osgeo.org/mailman/listinfo/foss-gps to manage your subscription For more information, check http://wiki.osgeo.org/wiki/FOSS-GPS
