[FOSS-GPS] Accurate timestamp in rtkpost
abmmusa
amusa2 at uic.edu
Sat Dec 5 13:48:49 PST 2015
Hi David,
Thanks for your answers. Overall, my application is following: I'm recording
video at 30 fps with an iPhone and simultaneously recording GPS data using
the Topcon receiver while driving. My end goal is to have accurate location
tag for every frame in the video. Now I can do that by matching timestamp of
the video frame to the timestamp of TopCon gps location. However, I can
visually see that the location of the video frame is not same as the
location from timestamp matching. It's possible that the iPhone timestamp
will not perfectly align with the GPS time, but I expect that it should
align within few milliseconds as the network time and actual GPS time should
be close enough.
As you said earlier, the GPS receiver reports in actual seconds and that is
the case for my data too. However, I thought during the solution I will get
accurate timestamp. But as I described above, visually things are not
matching. So is it possible that rtkpost is just reporting the receiver
timestamp, and not attempting to produce accurate solution for time from the
GPS data.
I tried recording at 5 Hz also, and the topcon data in rinex file is
rounded. Below is some data from both RINEX observation file and produced
solution.
2.10 OBSERVATION DATA G (GPS) RINEX VERSION /
TYPE
Topcon Link 7.1 25-NOV-15 18:45 PGM / RUN BY /
DATE
build July 25, 2002 (c) Topcon Positioning Systems COMMENT
log1125s_MX34 MARKER NAME
MARKER NUMBER
-Unknown- -Unknown- OBSERVER /
AGENCY
P87OWUNMX34 -Unknown- -Unknown- REC # / TYPE /
VERS
-Unknown- -Unknown- ANT # / TYPE
197218.0508 -4751023.4506 4236790.3266 APPROX POSITION
XYZ
0.0000 0.0000 0.0000 ANTENNA: DELTA
H/E/N
1 1 WAVELENGTH FACT
L1/2
2015 11 25 18 58 23.2000000 GPS TIME OF FIRST
OBS
2015 11 25 19 54 59.2000000 GPS TIME OF LAST OBS
0.200 INTERVAL
17 LEAP SECONDS
12 # OF SATELLITES
7 C1 P1 P2 L1 L2 D1 D2 # / TYPES OF
OBSERV
G 5 4951 3182 3182 4951 3182 4951 3182 PRN / # OF OBS
G10 16680 16297 16297 16680 16297 16680 16297 PRN / # OF OBS
G13 15686 14594 14594 15686 14594 15686 14594 PRN / # OF OBS
G14 20 0 0 20 0 20 0 PRN / # OF OBS
G15 16490 16213 16213 16490 16213 16490 16213 PRN / # OF OBS
G18 15773 14718 14718 15773 14718 15773 14718 PRN / # OF OBS
G20 16405 15984 15984 16405 15984 16405 15984 PRN / # OF OBS
G21 16844 16661 16661 16844 16661 16844 16661 PRN / # OF OBS
G22 10063 7686 7686 10063 7686 10063 7686 PRN / # OF OBS
G24 12416 11200 11200 12416 11200 12416 11200 PRN / # OF OBS
G27 7793 6354 6354 7793 6354 7793 6354 PRN / # OF OBS
G29 8512 7453 7453 8512 7453 8512 7453 PRN / # OF OBS
SE TPS 00000000 COMMENT
END OF HEADER
15 11 25 18 58 23.2000000 0 10G 5G10G13G15G18G20G21G22G24G29
24555318.542 24555317.9604 24555323.1574 129039006.493 5
100549922.87442
1155.332 900.259
21201697.714 21201696.7144 21201698.8844 111415672.515 7
86817407.27946
5473.874 4265.356
21817273.179 21817271.9744 21817272.2664 114650540.470 7
89338082.88345
1983.871 1545.874
20319507.735 20319507.5674 20319506.7674 106779734.742 8
83204987.16246
3903.913 3042.010
21943928.946 21943927.6294 21943926.7654 115316124.999 7
89856720.47144
5849.595 4558.126
20604626.734 20604625.2544 20604624.6354 108278042.649 8
84372499.78946
2785.491 2170.512
21462938.074 21462936.7894 21462935.5774 112788503.386 7
87887145.57845
5827.135 4540.625
24970969.735 24970969.1274 24970972.7974 131223333.550 4
102251953.89941
6873.734 5356.157
24335061.956 24335061.7814 24335065.6234 127881617.987 5
99648014.64143
7408.557 5772.902
22506510.317 22506509.9664 22506511.1734 118272501.298 6
92160397.74244
859.302 669.586
15 11 25 18 58 23.4000000 0 10G 5G10G13G15G18G20G21G22G24G29
24555275.280 24555274.6334 24555276.0644 129038775.623 5
100549742.98042
1153.394 898.748
21201489.496 21201488.2224 21201490.8034 111414577.672 7
86816554.15646
5474.695 4265.996
21817197.581 21817197.0274 21817196.4624 114650143.781 7
89337773.77645
1982.824 1545.058
20319359.120 20319358.6794 20319358.1344 106778954.011 8
83204378.80246
3903.342 3041.565
21943706.299 21943705.0444 21943704.1154 115314955.009 7
89855808.79444
5850.544 4558.865
20604520.679 20604519.8814 20604518.5224 108277485.613 7
84372065.73746
2784.816 2169.987
21462716.398 21462715.0634 21462714.1374 112787337.900 7
87886237.40445
5827.705 4541.069
24970707.575 24970708.1614 24970710.3974 131221958.787 4
102250882.65241
6875.172 5357.277
24334779.989 24334780.0034 24334783.7614 127880136.278 5
99646860.06443
7407.977 5772.449
22506477.461 22506477.6104 22506478.5864 118272329.453 6
92160263.83644
859.397 669.660
% program : RTKPOST ver.2.4.17329288 -87.630811939 155.5716 2 6
0.0249 0.0200 0.0711 -0.0078 -0.0133 -0.0278 0.00 2.1
% inp file :
C:\Users\bits\Desktop\piksi_obs_files\lakeshore112515\rinex\log1329s.15O
% inp file :
C:\Users\bits\Desktop\piksi_obs_files\lakeshore112515\cors_ccsk\ccsk3290.15o
% inp file :
C:\Users\bits\Desktop\piksi_obs_files\lakeshore112515\rinex\log1329s.15*
% inp file :
C:\Users\bits\Desktop\piksi_obs_files\lakeshore112515\gps_orbit\igr18723.sp3
% obs start : 2015/11/25 18:58:23.2 GPST (week1872 327503.2s)
% obs end : 2015/11/25 19:54:59.2 GPST (week1872 330899.2s)
% pos mode : kinematic
% freqs : L1+L2
% solution : combined
% elev mask : 15.0 deg
% snr mask : 0.0 dBHz
% dynamics : off
% tidecorr : off
% ionos opt : iono-free
% tropo opt : saastamoinen
% ephemeris : precise
% navi sys : gps glonass
% amb res : continuous
% amb glo : on
% val thres : 3.0
% antenna1 : ( 0.0000 0.0000 0.0000)
% antenna2 : ( 0.0000 0.0000 0.0000)
% ref pos : 42.063470775 -87.767146535 168.6722
%
%
(lat/lon/height=WGS84/ellipsoidal,Q=1:fix,2:float,3:sbas,4:dgps,5:single,6:ppp,ns=#
of satellites)
% GPST latitude(deg) longitude(deg) height(m) Q ns
sdn(m) sde(m) sdu(m) sdne(m) sdeu(m) sdun(m) age(s) ratio
2015/11/25 18:58:23.200 41.867328540 -87.630858799 155.6244 2 6
0.0247 0.0199 0.0713 -0.0074 -0.0134 -0.0278 0.20 1.9
2015/11/25 18:58:23.400 41.867328683 -87.630852351 155.6219 2 6
0.0247 0.0200 0.0712 -0.0075 -0.0134 -0.0278 0.40 2.0
2015/11/25 18:58:23.600 41.867328759 -87.630846515 155.6055 2 6
0.0247 0.0200 0.0712 -0.0076 -0.0134 -0.0278 0.60 2.0
2015/11/25 18:58:23.800 41.867328811 -87.630841287 155.6038 2 6
0.0247 0.0200 0.0712 -0.0075 -0.0134 -0.0278 0.80 2.1
2015/11/25 18:58:24.000 41.867328892 -87.630836581 155.5969 2 6
0.0247 0.0200 0.0712 -0.0075 -0.0134 -0.0278 0.00 2.1
2015/11/25 18:58:24.200 41.867328959 -87.630832456 155.6191 2 6
0.0247 0.0200 0.0712 -0.0076 -0.0134 -0.0278 0.20 2.2
2015/11/25 18:58:24.400 41.867328998 -87.630828664 155.5892 2 6
0.0248 0.0200 0.0712 -0.0076 -0.0133 -0.0278 0.40 2.1
2015/11/25 18:58:24.600 41.867329055 -87.630825419 155.5930 2 6
0.0248 0.0201 0.0712 -0.0077 -0.0133 -0.0278 0.60 2.0
2015/11/25 18:58:24.800 41.867329090 -87.630822460 155.5815 2 6
0.0248 0.0200 0.0712 -0.0077 -0.0134 -0.0278 0.80 2.1
2015/11/25 18:58:25.000 41.867329141 -87.630819886 155.5689 2 6
0.0248 0.0200 0.0711 -0.0076 -0.0133 -0.0278 0.00 2.1
2015/11/25 18:58:25.200 41.867329192 -87.630817733 155.5866 2 6
0.0248 0.0200 0.0712 -0.0077 -0.0134 -0.0278 0.20 2.1
2015/11/25 18:58:25.400 41.867329241 -87.630815873 155.5773 2 6
0.0249 0.0199 0.0712 -0.0076 -0.0134 -0.0278 0.40 2.0
2015/11/25 18:58:25.600 41.867329224 -87.630814336 155.5778 2 6
0.0249 0.0199 0.0711 -0.0075 -0.0134 -0.0278 0.60 2.1
2015/11/25 18:58:25.800 41.867329257 -87.630812982 155.5701 2 6
0.0248 0.0200 0.0711 -0.0078 -0.0134 -0.0277 0.80 2.1
2015/11/25 18:58:26.000 41.867329288 -87.630811939 155.5716 2 6
0.0249 0.0200 0.0711 -0.0078 -0.0133 -0.0278 0.00 2.1
2015/11/25 18:58:26.200 41.867329306 -87.630811130 155.5681 2 6
0.0249 0.0200 0.0712 -0.0078 -0.0134 -0.0278 0.20 2.1
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