Jump in computed satellite position

[pedromiguelcp]

I've been using an RTKLIB-based receiver (GNSS-SDR) to process both real-world and simulated RF data. When processing data from a simulator (R&SSMW200A), I noticed some jumps in the estimated receiver position that I traced back to a jump in the pseudorange observable caused by a jump in the computed satellite position. So far, I'm not really sure if this behavior is caused by the simulated data (I haven't had the same behavior with real data) or the receiver itself, so I'm looking for help on this.

Below is the debug data and analysis specifically affecting Galileo satellite PRN E04 (SV63), however, the same problem was verified in other Galileo satellite signals. The debug reveals a sudden jump in the computed satellite position, which appears to result from an E5 ephemeris update that is applied inconsistently. More precisely, the mean anomaly (M0) is updated independently of the corresponding reference time (toe) and other orbital parameters. This leads to a temporary mismatch in the satellite's orbital definition, causing the receiver to compute an incorrect satellite position. Once toe is eventually updated to match the new M0, the satellite position returns to its expected trajectory.

I believe this behavior is inconsistent with how real GNSS satellites operate, where ephemeris updates are synchronized across all parameters. The evidence suggests that the GNSS simulator may be broadcasting partial or desynchronized ephemeris data across signals, such as E1 and E5a.
Additionally, the issue does not consistently affect the same satellite. It appears to occur randomly across different runs with the same simulator recording, sometimes impacting one satellite and not another, and other times affecting both or neither.

True Position:
ECEF (X,Y,Z,t[meters]) = (omitted), -705574, 4.207012e+06
Lat = (omitted) [deg], Long = -8.48536946111111 [deg], Height= 185.702 [m]

Log info:
sat = Internal satellite number
time = GPS Time of Week (TOW) [s]
toe = Time of Ephemeris - reference time for orbital parameters [s]
M0 = Mean Anomaly at toe - defines satellite position in orbit at toe [radians]
sqrtA = Square root of the semi-major axis (A), related to orbital radius [m]
e = Orbital eccentricity - shape of the orbit (0 = circular)
i0 = Inclination angle [radians]
iode = Issue of Data (Ephemeris) - data version
X, Y, Z = satellite 3D position [m]
dts = satellite clock correction (time offset from GPS time) [s]

`12:32:13.018971 rtklib_ephemeris.cc:821] Eph sat=63 time=595220 toe=594000 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.74777e+07 Y=-1.96348e+06 Z=1.08319e+07 dts=-0.000182327
12:32:13.020283 rtklib_solver.cc:1801] RTKLIB Position at RX TOW = 595220 in ECEF (X,Y,Z,t[meters]) = (omitted), -705577, 4.20699e+06, 0.0105328
12:32:13.020298 rtklib_solver.cc:1813] RTKLIB Position at 2025-Mar-15 21:20:01.880000 is Lat = (omitted) [deg], Long = -8.48544 [deg], Height= 156.414 [m] RX time offset= 0.0105328 [s]

12:32:13.094882 rtklib_ephemeris.cc:821] Eph sat=63 time=595220 toe=594000 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.74776e+07 Y=-1.96347e+06 Z=1.0832e+07 dts=-0.000182327
12:32:13.096197 rtklib_solver.cc:1801] RTKLIB Position at RX TOW = 595220 in ECEF (X,Y,Z,t[meters]) = (omitted), -705577, 4.207e+06, 0.0105328
12:32:13.096215 rtklib_solver.cc:1813] RTKLIB Position at 2025-Mar-15 21:20:01.920000 is Lat = (omitted) [deg], Long = -8.48544 [deg], Height= 159.538 [m] RX time offset= 0.0105328 [s]

12:32:13.124214 rtklib_ephemeris.cc:821] Eph sat=63 time=595220 toe=594000 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.74776e+07 Y=-1.96346e+06 Z=1.0832e+07 dts=-0.000182327
12:32:13.125531 rtklib_solver.cc:1801] RTKLIB Position at RX TOW = 595220 in ECEF (X,Y,Z,t[meters]) = (omitted), -705575, 4.207e+06, 0.0105328
12:32:13.125547 rtklib_solver.cc:1813] RTKLIB Position at 2025-Mar-15 21:20:01.940000 is Lat = (omitted) [deg], Long = -8.48541 [deg], Height= 160.129 [m] RX time offset= 0.0105328 [s]

12:32:13.319868 rtklib_ephemeris.cc:821] Eph sat=63 time=595220 toe=594000 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.74775e+07 Y=-1.96342e+06 Z=1.08324e+07 dts=-0.000182327
12:32:13.360900 rtklib_ephemeris.cc:821] Eph sat=63 time=595220 toe=594000 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.74775e+07 Y=-1.96342e+06 Z=1.08324e+07 dts=-0.000182327
12:32:13.417745 rtklib_ephemeris.cc:821] Eph sat=63 time=595220 toe=594000 M0=1.54891 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.68639e+07 Y=-567561 Z=1.24201e+07 dts=-0.000182327 (jump occurs here, after M0 parameter changes)

12:32:25.234133 rtklib_ephemeris.cc:821] Eph sat=63 time=595227 toe=594000 M0=1.54891 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.6856e+07 Y=-565100 Z=1.24372e+07 dts=-0.000182327
12:32:25.234609 rtklib_solver.cc:1801] RTKLIB Position at RX TOW = 595227 in ECEF (X,Y,Z,t[meters]) = (omitted), -655382, 4.61957e+06, -0.0681602
12:32:25.234625 rtklib_solver.cc:1813] RTKLIB Position at 2025-Mar-15 21:20:08.620611 is Lat = (omitted) [deg], Long = -7.66159 [deg], Height= 377686 [m] RX time offset= -0.0681602 [s]

12:32:29.711074 rtklib_ephemeris.cc:821] Eph sat=63 time=595229 toe=594000 M0=1.54891 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.6853e+07 Y=-564158 Z=1.24437e+07 dts=-0.000182327
12:32:29.711581 rtklib_solver.cc:1801] RTKLIB Position at RX TOW = 595229 in ECEF (X,Y,Z,t[meters]) = (omitted), -366810, 4.5422e+06, -0.0876422
12:32:29.711608 rtklib_solver.cc:1813] RTKLIB Position at 2025-Mar-15 21:20:11.120808 is Lat = (omitted) [deg], Long = -4.14172 [deg], Height= 445039 [m] RX time offset= -0.0876422 [s]

12:32:38.170011 rtklib_ephemeris.cc:821] Eph sat=63 time=595234 toe=594600 M0=1.54891 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.74628e+07 Y=-1.95897e+06 Z=1.08703e+07 dts=-0.000182327
12:32:38.170856 rtklib_solver.cc:1801] RTKLIB Position at RX TOW = 595234 in ECEF (X,Y,Z,t[meters]) = (omitted), -705571, 4.207e+06, -0.0694685
12:32:38.170871 rtklib_solver.cc:1813] RTKLIB Position at 2025-Mar-15 21:20:16.040000 is Lat = (omitted) [deg], Long = -8.48531 [deg], Height= 186.401 [m] RX time offset= -0.0694685 [s]

12:32:38.644851 rtklib_ephemeris.cc:821] Eph sat=63 time=595234 toe=594600 M0=1.54891 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.74625e+07 Y=-1.95888e+06 Z=1.0871e+07 dts=-0.000182327
12:32:38.645457 rtklib_solver.cc:1801] RTKLIB Position at RX TOW = 595234 in ECEF (X,Y,Z,t[meters]) = (omitted), -705573, 4.20699e+06, 0.0105314
12:32:38.645471 rtklib_solver.cc:1813] RTKLIB Position at 2025-Mar-15 21:20:16.400000 is Lat = (omitted) [deg], Long = -8.48539 [deg], Height= 156.422 [m] RX time offset= 0.0105314 [s]

12:39:58.552119 rtklib_ephemeris.cc:821] Eph sat=63 time=595493 toe=594600 M0=1.54891 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.71854e+07 Y=-1.87082e+06 Z=1.15619e+07 dts=-0.000182329`

Scooping into the Ephemeris data:

`12:00:00.946653 Eph sat=63 time=594096 toe=593400 M0=1.40014 sqrtA=5440.6 e=0.000349108 i0=0.963609 iode=0 X=2.84932e+07 Y=-2.21778e+06 Z=7.7036e+06 dts=-0.000182316

12:15:09.543192 Eph sat=63 time=594620 toe=593400 M0=1.40014 sqrtA=5440.6 e=0.000349108 i0=0.963609 iode=0 X=2.80588e+07 Y=-2.12319e+06 Z=9.1848e+06 dts=-0.000182321

12:15:09.593331 Eph sat=63 time=594620 toe=593400 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963609 iode=0 X=2.7537e+07 Y=-759711 Z=1.08324e+07 dts=-0.000182321

12:15:33.823103 Eph sat=63 time=594634 toe=593400 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963609 iode=0 X=2.75226e+07 Y=-755991 Z=1.08694e+07 dts=-0.000182321

12:15:33.859453 Eph sat=63 time=594634 toe=593400 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963609 iode=0 X=2.75226e+07 Y=-755986 Z=1.08695e+07 dts=-0.000182321

12:15:33.898502 Eph sat=63 time=594634 toe=593400 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963609 iode=0 X=2.75225e+07 Y=-755980 Z=1.08695e+07 dts=-0.000182321

12:15:33.932543 Eph sat=63 time=594634 toe=593400 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963609 iode=0 X=2.75225e+07 Y=-755975 Z=1.08696e+07 dts=-0.000182321

12:15:33.979122 Eph sat=63 time=594634 toe=594000 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.80464e+07 Y=-2.12015e+06 Z=9.22336e+06 dts=-0.000182321

12:32:10.670552 Eph sat=63 time=595218 toe=594000 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.7479e+07 Y=-1.96389e+06 Z=1.08284e+07 dts=-0.000182327

12:32:10.697229 Eph sat=63 time=595219 toe=594000 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.7479e+07 Y=-1.96388e+06 Z=1.08284e+07 dts=-0.000182327

12:32:12.503458 Eph sat=63 time=595219 toe=594000 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.7478e+07 Y=-1.96357e+06 Z=1.08311e+07 dts=-0.000182327

12:32:12.544605 Eph sat=63 time=595220 toe=594000 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.7478e+07 Y=-1.96357e+06 Z=1.08311e+07 dts=-0.000182327

12:32:13.018971 Eph sat=63 time=595220 toe=594000 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.74777e+07 Y=-1.96348e+06 Z=1.08319e+07 dts=-0.000182327

12:32:13.094882 Eph sat=63 time=595220 toe=594000 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.74776e+07 Y=-1.96347e+06 Z=1.0832e+07 dts=-0.000182327

12:32:13.124214 Eph sat=63 time=595220 toe=594000 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.74776e+07 Y=-1.96346e+06 Z=1.0832e+07 dts=-0.000182327

12:32:13.319868 Eph sat=63 time=595220 toe=594000 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.74775e+07 Y=-1.96342e+06 Z=1.08324e+07 dts=-0.000182327

12:32:13.360900 Eph sat=63 time=595220 toe=594000 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.74775e+07 Y=-1.96342e+06 Z=1.08324e+07 dts=-0.000182327

12:32:13.417745 Eph sat=63 time=595220 toe=594000 M0=1.54891 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.68639e+07 Y=-567561 Z=1.24201e+07 dts=-0.000182327

12:32:25.234133 Eph sat=63 time=595227 toe=594000 M0=1.54891 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.6856e+07 Y=-565100 Z=1.24372e+07 dts=-0.000182327

12:32:29.711074 Eph sat=63 time=595229 toe=594000 M0=1.54891 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.6853e+07 Y=-564158 Z=1.24437e+07 dts=-0.000182327

12:32:38.170011 Eph sat=63 time=595234 toe=594600 M0=1.54891 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.74628e+07 Y=-1.95897e+06 Z=1.08703e+07 dts=-0.000182327

12:32:38.644851 Eph sat=63 time=595234 toe=594600 M0=1.54891 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.74625e+07 Y=-1.95888e+06 Z=1.0871e+07 dts=-0.000182327

12:39:58.552119 Eph sat=63 time=595493 toe=594600 M0=1.54891 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.71854e+07 Y=-1.87082e+06 Z=1.15619e+07 dts=-0.000182329`

M0 changes from M0=1.47452 to M0=1.54891 at 12:32:13.417745, indicating a new ephemeris has been received. But all other parameters remain constant. At this moment, the SV63 3D position suffers a huge jump compared to its position from 568ms before (12:32:13.360900).
11.8 seconds later, at 12:32:25.234133, the satellite position is again computed. Compared to the previous iteration, all parameters remain the same except for the GPS TOW, which changes from 595220s to 595227s. The resulting satellite position changes but maintains the huge offset from the previous iteration.
4.5 seconds later, at 12:32:29.711074, the satellite position is again computed. Compared to the previous iteration, all parameters remain the same except for the GPS TOW, which changes from 595227s to 595229s. The resulting satellite position changes but maintains the huge offset from the previous iteration.
8.5 seconds later, at 12:32:38.170011, the satellite position is again computed. Compared to the previous iteration, GPS TOW changes from 595229s to 595234s, and toe changes from 594000s to 594600s. The computed satellite position gets back to around the values before the jump, and the estimated receiver position approximates the true position.

A possible justification for this problem is that the parameters used for the satellite position computation do not change at the same time as they are supposed to. The satellite position goes back to normal with the new value of M0=1.54891, indicating that the value of that parameter is not wrong, but maybe paired with the wrong values of the other parameters.

The image below shows the satellite Y position evolution when M0 and toe are updated:

This behavior happens with other satellites, too. Sometimes it happens in more than one satellite, and sometimes it does not even happen during the 25-minute recording. With the same recording, there is a certain randomness. With the same run, looking into other satellite logs, M0 and toe are updated at the same time. However, it can happen that those parameters are not updated at the same time at a given moment (=jump in satellite position), but they do not match the PVT timing epoch, so there is no effect on positioning. This behavior happened with other satellites in other runs, and the satellite PRN E04 was ok.

[tomojitakasu]

A set of Galileo F/NAV messages are separated into multiple words and sent to users. The toe and M0 parameters are stored in different words. Users must confirm the consistency among these words by using the IOD_nav, which is located in the second field of each word.

Similarly, in the case of I/NAV messages, while toe and M0 are stored in the same word, other parameters are located in different words. Therefore, consistency checks using IOD_nav are also required. For detailed structure of F/NAV or I/NAV, refer to Galileo OS-SIS-ICD.

In RTKLIB, the decode_gal_fnav() or decode_gal_inav() functions, found in src/rcvraw.c and called by CONVBIN or RTKCONV, check the consistency among raw navigation message words and discard them if an inconsistency is found.

In your case, these consistency checks do not appear to be functioning correctly. One possibility is that the IOD_nav might be duplicated across different sets of F/NAV or I/NAV messages.

[pedromiguelcp]

Thank you for your response @tomojitakasu!

I just did another run with the same recording file and receiver configuration. This time, the SV63 position did not jump, and M0 and toe are updated at the same time. Instead, got jumps in SV68 and SV78 due to the same problem.

Here is the log for all Galileo satellites:

`10:33:32.768651 rtklib_ephemeris.cc:823] Eph sat=63 time=594088 toe=593400 toc=593400 ttr=594085 week=2357 M0=1.40014 sqrtA=5440.6 e=0.000349108 i0=0.963609 iode=0 X=2.84993e+07 Y=-2.21893e+06 Z=7.68067e+06 dts=-0.000182316
10:48:49.095921 rtklib_ephemeris.cc:823] Eph sat=63 time=594634 toe=593400 toc=593400 ttr=594595 week=2357 M0=1.40014 sqrtA=5440.6 e=0.000349108 i0=0.963609 iode=0 X=2.80464e+07 Y=-2.12016e+06 Z=9.22331e+06 dts=-0.000182321
10:48:49.140971 rtklib_ephemeris.cc:823] Eph sat=63 time=594634 toe=594000 toc=594000 ttr=594625 week=2357 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.80464e+07 Y=-2.12015e+06 Z=9.22336e+06 dts=-0.000182321
11:05:55.266544 rtklib_ephemeris.cc:823] Eph sat=63 time=595234 toe=594000 toc=594000 ttr=595195 week=2357 M0=1.47452 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.74631e+07 Y=-1.95905e+06 Z=1.08696e+07 dts=-0.000182327
11:05:55.314225 rtklib_ephemeris.cc:823] Eph sat=63 time=595234 toe=594600 toc=594600 ttr=595225 week=2357 M0=1.54891 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.74631e+07 Y=-1.95904e+06 Z=1.08696e+07 dts=-0.000182327
11:14:33.558357 rtklib_ephemeris.cc:823] Eph sat=63 time=595534 toe=594600 toc=594600 ttr=595525 week=2357 M0=1.54891 sqrtA=5440.6 e=0.000349108 i0=0.963608 iode=0 X=2.71395e+07 Y=-1.85556e+06 Z=1.16719e+07 dts=-0.00018233

10:34:34.561585 rtklib_ephemeris.cc:823] Eph sat=68 time=594126 toe=593400 toc=593400 ttr=594115 week=2357 M0=-0.109792 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.40187e+07 Y=-1.38893e+07 Z=-1.02826e+07 dts=-0.000812893
10:48:26.412761 rtklib_ephemeris.cc:823] Eph sat=68 time=594620 toe=593400 toc=593400 ttr=594565 week=2357 M0=-0.109792 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.44655e+07 Y=-1.40584e+07 Z=-8.90755e+06 dts=-0.0008129
10:48:26.436972 rtklib_ephemeris.cc:823] Eph sat=68 time=594620 toe=593400 toc=594000 ttr=594570 week=2357 M0=-0.0354056 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.55106e+07 Y=-1.31532e+07 Z=-7.19355e+06 dts=-0.0008129
10:48:26.487505 rtklib_ephemeris.cc:823] Eph sat=68 time=594620 toe=593400 toc=594000 ttr=594570 week=2357 M0=-0.0354056 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.55107e+07 Y=-1.31532e+07 Z=-7.19349e+06 dts=-0.0008129
10:48:26.521703 rtklib_ephemeris.cc:823] Eph sat=68 time=594620 toe=593400 toc=594000 ttr=594570 week=2357 M0=-0.0354056 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.55107e+07 Y=-1.31532e+07 Z=-7.19343e+06 dts=-0.0008129
10:48:49.141001 rtklib_ephemeris.cc:823] Eph sat=68 time=594634 toe=594000 toc=594000 ttr=594625 week=2357 M0=-0.0354056 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.44769e+07 Y=-1.4063e+07 Z=-8.86865e+06 dts=-0.0008129
11:05:32.501529 rtklib_ephemeris.cc:823] Eph sat=68 time=595220 toe=594000 toc=594000 ttr=595195 week=2357 M0=-0.0354056 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.49109e+07 Y=-1.42564e+07 Z=-7.1936e+06 dts=-0.000812909
11:05:32.547634 rtklib_ephemeris.cc:823] Eph sat=68 time=595220 toe=594000 toc=594600 ttr=595170 week=2357 M0=0.0389804 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.58567e+07 Y=-1.33189e+07 Z=-5.43977e+06 dts=-0.000812909
11:05:55.314254 rtklib_ephemeris.cc:823] Eph sat=68 time=595234 toe=594000 toc=594600 ttr=595170 week=2357 M0=0.0389804 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.58634e+07 Y=-1.33225e+07 Z=-5.3991e+06 dts=-0.000812909
11:05:55.341617 rtklib_ephemeris.cc:823] Eph sat=68 time=595234 toe=594600 toc=594600 ttr=595225 week=2357 M0=0.0389804 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.49199e+07 Y=-1.42608e+07 Z=-7.15362e+06 dts=-0.000812909
11:14:33.558389 rtklib_ephemeris.cc:823] Eph sat=68 time=595534 toe=594600 toc=594600 ttr=595525 week=2357 M0=0.0389804 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.51015e+07 Y=-1.43538e+07 Z=-6.27945e+06 dts=-0.000812913

10:33:32.768685 rtklib_ephemeris.cc:823] Eph sat=69 time=594088 toe=593400 toc=593400 ttr=594085 week=2357 M0=1.15593 sqrtA=5440.62 e=0.000127912 i0=1.00003 iode=0 X=1.94934e+07 Y=-707837 Z=2.22624e+07 dts=-0.000696401
10:48:42.867967 rtklib_ephemeris.cc:823] Eph sat=69 time=594630 toe=593400 toc=593400 ttr=594595 week=2357 M0=1.15593 sqrtA=5440.62 e=0.000127912 i0=1.00003 iode=0 X=2.03837e+07 Y=85930.1 Z=2.14621e+07 dts=-0.000696402
10:48:42.901865 rtklib_ephemeris.cc:823] Eph sat=69 time=594630 toe=594000 toc=594000 ttr=594620 week=2357 M0=1.23032 sqrtA=5440.62 e=0.000127912 i0=1.00003 iode=0 X=2.03837e+07 Y=85958.3 Z=2.1462e+07 dts=-0.000696402
11:05:49.178608 rtklib_ephemeris.cc:823] Eph sat=69 time=595230 toe=594000 toc=594000 ttr=595195 week=2357 M0=1.23032 sqrtA=5440.62 e=0.000127912 i0=1.00003 iode=0 X=2.13683e+07 Y=881843 Z=2.04635e+07 dts=-0.000696403
11:05:49.221514 rtklib_ephemeris.cc:823] Eph sat=69 time=595230 toe=594600 toc=594600 ttr=595220 week=2357 M0=1.3047 sqrtA=5440.62 e=0.000127912 i0=1.00003 iode=0 X=2.13684e+07 Y=881868 Z=2.04635e+07 dts=-0.000696403
11:14:33.558418 rtklib_ephemeris.cc:823] Eph sat=69 time=595534 toe=594600 toc=594600 ttr=595525 week=2357 M0=1.3047 sqrtA=5440.62 e=0.000127912 i0=1.00003 iode=0 X=2.18639e+07 Y=1.25155e+06 Z=1.99136e+07 dts=-0.000696404

10:32:56.872048 rtklib_ephemeris.cc:823] Eph sat=70 time=594066 toe=593400 toc=593400 ttr=594055 week=2357 M0=0.992606 sqrtA=5440.62 e=0.000475155 i0=0.997088 iode=0 X=1.21922e+07 Y=-1.04987e+07 Z=2.48376e+07 dts=-0.00161043
10:48:49.095862 rtklib_ephemeris.cc:823] Eph sat=70 time=594634 toe=593400 toc=593400 ttr=594570 week=2357 M0=0.992606 sqrtA=5440.62 e=0.000475155 i0=0.997088 iode=0 X=1.32139e+07 Y=-9.51943e+06 Z=2.47104e+07 dts=-0.00161058
10:48:49.140904 rtklib_ephemeris.cc:823] Eph sat=70 time=594634 toe=594000 toc=594000 ttr=594625 week=2357 M0=1.06699 sqrtA=5440.62 e=0.000475155 i0=0.997088 iode=0 X=1.32139e+07 Y=-9.5194e+06 Z=2.47104e+07 dts=-0.00161058
11:05:55.266486 rtklib_ephemeris.cc:823] Eph sat=70 time=595234 toe=594000 toc=594000 ttr=595195 week=2357 M0=1.06699 sqrtA=5440.62 e=0.000475155 i0=0.997088 iode=0 X=1.43321e+07 Y=-8.54507e+06 Z=2.4443e+07 dts=-0.00161074
11:05:55.314167 rtklib_ephemeris.cc:823] Eph sat=70 time=595234 toe=594600 toc=594600 ttr=595225 week=2357 M0=1.14138 sqrtA=5440.62 e=0.000475155 i0=0.997088 iode=0 X=1.43322e+07 Y=-8.54504e+06 Z=2.4443e+07 dts=-0.00161074
11:14:33.558291 rtklib_ephemeris.cc:823] Eph sat=70 time=595534 toe=594600 toc=594600 ttr=595525 week=2357 M0=1.14138 sqrtA=5440.62 e=0.000475155 i0=0.997088 iode=0 X=1.49042e+07 Y=-8.08244e+06 Z=2.42582e+07 dts=-0.00161082

10:32:56.872087 rtklib_ephemeris.cc:823] Eph sat=71 time=594066 toe=593400 toc=593400 ttr=594055 week=2357 M0=2.19541 sqrtA=5440.61 e=0.00050771 i0=0.997101 iode=0 X=2.30746e+07 Y=7.85919e+06 Z=1.68094e+07 dts=-0.000726807
10:48:49.095892 rtklib_ephemeris.cc:823] Eph sat=71 time=594634 toe=593400 toc=593400 ttr=594570 week=2357 M0=2.19541 sqrtA=5440.61 e=0.00050771 i0=0.997101 iode=0 X=2.3787e+07 Y=8.44797e+06 Z=1.54795e+07 dts=-0.000726916
10:48:49.140939 rtklib_ephemeris.cc:823] Eph sat=71 time=594634 toe=594000 toc=594000 ttr=594625 week=2357 M0=2.2698 sqrtA=5440.61 e=0.00050771 i0=0.997101 iode=0 X=2.3787e+07 Y=8.44799e+06 Z=1.54795e+07 dts=-0.000726916
11:05:55.266515 rtklib_ephemeris.cc:823] Eph sat=71 time=595234 toe=594000 toc=594000 ttr=595195 week=2357 M0=2.2698 sqrtA=5440.61 e=0.00050771 i0=0.997101 iode=0 X=2.45049e+07 Y=8.97754e+06 Z=1.39916e+07 dts=-0.00072703
11:05:55.314195 rtklib_ephemeris.cc:823] Eph sat=71 time=595234 toe=594600 toc=594600 ttr=595225 week=2357 M0=2.34418 sqrtA=5440.61 e=0.00050771 i0=0.997101 iode=0 X=2.45049e+07 Y=8.97755e+06 Z=1.39916e+07 dts=-0.00072703
11:14:33.558321 rtklib_ephemeris.cc:823] Eph sat=71 time=595534 toe=594600 toc=594600 ttr=595525 week=2357 M0=2.34418 sqrtA=5440.61 e=0.00050771 i0=0.997101 iode=0 X=2.48477e+07 Y=9.20752e+06 Z=1.32169e+07 dts=-0.000727087

10:32:56.872145 rtklib_ephemeris.cc:823] Eph sat=78 time=594066 toe=593400 toc=593400 ttr=594055 week=2357 M0=2.44258 sqrtA=5440.61 e=0.000356557 i0=0.969087 iode=0 X=1.48086e+07 Y=1.21346e+07 Z=2.2586e+07 dts=0.00151245
10:48:26.412868 rtklib_ephemeris.cc:823] Eph sat=78 time=594620 toe=593400 toc=593400 ttr=594565 week=2357 M0=2.44258 sqrtA=5440.61 e=0.000356557 i0=0.969087 iode=0 X=1.35822e+07 Y=1.24684e+07 Z=2.31681e+07 dts=0.00151248
10:48:26.437088 rtklib_ephemeris.cc:823] Eph sat=78 time=594620 toe=593400 toc=594000 ttr=594570 week=2357 M0=2.51696 sqrtA=5440.61 e=0.000356557 i0=0.969087 iode=0 X=1.16647e+07 Y=1.34218e+07 Z=2.3675e+07 dts=0.00151248
10:48:49.096040 rtklib_ephemeris.cc:823] Eph sat=78 time=594634 toe=593400 toc=594000 ttr=594570 week=2357 M0=2.51696 sqrtA=5440.61 e=0.000356557 i0=0.969087 iode=0 X=1.16334e+07 Y=1.34311e+07 Z=2.36851e+07 dts=0.00151248
10:48:49.141090 rtklib_ephemeris.cc:823] Eph sat=78 time=594634 toe=594000 toc=594000 ttr=594625 week=2357 M0=2.51696 sqrtA=5440.61 e=0.000356557 i0=0.969087 iode=0 X=1.35515e+07 Y=1.24775e+07 Z=2.31812e+07 dts=0.00151248
11:05:32.456272 rtklib_ephemeris.cc:823] Eph sat=78 time=595220 toe=594000 toc=594000 ttr=595195 week=2357 M0=2.51696 sqrtA=5440.61 e=0.000356557 i0=0.969087 iode=0 X=1.22407e+07 Y=1.28987e+07 Z=2.3675e+07 dts=0.00151251
11:05:32.501637 rtklib_ephemeris.cc:823] Eph sat=78 time=595220 toe=594000 toc=594600 ttr=595170 week=2357 M0=2.59135 sqrtA=5440.61 e=0.000356557 i0=0.969087 iode=0 X=1.02992e+07 Y=1.38639e+07 Z=2.40511e+07 dts=0.00151251
11:05:55.266712 rtklib_ephemeris.cc:823] Eph sat=78 time=595234 toe=594000 toc=594600 ttr=595170 week=2357 M0=2.59135 sqrtA=5440.61 e=0.000356557 i0=0.969087 iode=0 X=1.02678e+07 Y=1.38748e+07 Z=2.40582e+07 dts=0.00151251
11:05:55.314350 rtklib_ephemeris.cc:823] Eph sat=78 time=595234 toe=594600 toc=594600 ttr=595225 week=2357 M0=2.59135 sqrtA=5440.61 e=0.000356557 i0=0.969087 iode=0 X=1.22097e+07 Y=1.29095e+07 Z=2.36851e+07 dts=0.00151251
11:14:33.558478 rtklib_ephemeris.cc:823] Eph sat=78 time=595534 toe=594600 toc=594600 ttr=595525 week=2357 M0=2.59135 sqrtA=5440.61 e=0.000356557 i0=0.969087 iode=0 X=1.1536e+07 Y=1.31526e+07 Z=2.38884e+07 dts=0.00151253

10:32:56.872117 rtklib_ephemeris.cc:823] Eph sat=84 time=594066 toe=593400 toc=593400 ttr=594055 week=2357 M0=2.1485 sqrtA=5440.61 e=0.000146106 i0=0.963789 iode=0 X=4.60199e+06 Y=-2.88939e+07 Z=4.50597e+06 dts=1.52243e-05
10:48:49.096010 rtklib_ephemeris.cc:823] Eph sat=84 time=594634 toe=593400 toc=593400 ttr=594570 week=2357 M0=2.1485 sqrtA=5440.61 e=0.000146106 i0=0.963789 iode=0 X=4.61698e+06 Y=-2.91053e+07 Z=2.81403e+06 dts=1.52246e-05
10:48:49.141060 rtklib_ephemeris.cc:823] Eph sat=84 time=594634 toe=594000 toc=594000 ttr=594625 week=2357 M0=2.22289 sqrtA=5440.61 e=0.000146106 i0=0.96379 iode=0 X=4.61698e+06 Y=-2.91053e+07 Z=2.81397e+06 dts=1.52246e-05
11:05:55.314313 rtklib_ephemeris.cc:823] Eph sat=84 time=595234 toe=594000 toc=594000 ttr=595195 week=2357 M0=2.22289 sqrtA=5440.61 e=0.000146106 i0=0.96379 iode=0 X=4.60193e+06 Y=-2.92262e+07 Z=1.01166e+06 dts=1.52248e-05
11:05:55.341687 rtklib_ephemeris.cc:823] Eph sat=84 time=595234 toe=594600 toc=594600 ttr=595225 week=2357 M0=2.29727 sqrtA=5440.61 e=0.000146106 i0=0.96379 iode=0 X=4.60193e+06 Y=-2.92262e+07 Z=1.0116e+06 dts=1.52248e-05
11:14:33.558449 rtklib_ephemeris.cc:823] Eph sat=84 time=595534 toe=594600 toc=594600 ttr=595525 week=2357 M0=2.29727 sqrtA=5440.61 e=0.000146106 i0=0.96379 iode=0 X=4.58534e+06 Y=-2.92462e+07 Z=106464 dts=1.52249e-05`

I'm trying to understand why this behavior is not constant and consistent. I get different results for each run, which makes it difficult to identify if the problem is on the receiver side or the data itself. I believe the problem is with the simulated data because I don´t see this behavior with real-world data, but shouldn't these jumps in satellite positions (due to unsynchronized update of parameters) occur consistently every run with the simulated data?

[pedromiguelcp]

Below is the debug with navigation data information for SV68 (with jump in position) and SV84 (no jump in position):

SV84
10:32:56.872117 rtklib_ephemeris.cc:823] Eph sat=84 time=594066 toe=593400 toc=593400 ttr=594055 week=2357 M0=2.1485 sqrtA=5440.61 e=0.000146106 i0=0.963789 iode=0 X=4.60199e+06 Y=-2.88939e+07 Z=4.50597e+06 dts=1.52243e-05 10:48:42.876960 galileo_telemetry_decoder_gs.cc:666] Galileo E5a CRC correct in channel 32 from satellite Galileo PRN E19 (Block IOV-FM3) with CN0=42.2653 dB-Hz 10:48:42.901893 rtklib_ephemeris.cc:823] Eph sat=84 time=594630 toe=593400 toc=593400 ttr=594570 week=2357 M0=2.1485 sqrtA=5440.61 e=0.000146106 i0=0.963789 iode=0 X=4.61699e+06 Y=-2.91042e+07 Z=2.82528e+06 dts=1.52246e-05 10:48:49.096010 rtklib_ephemeris.cc:823] Eph sat=84 time=594634 toe=593400 toc=593400 ttr=594570 week=2357 M0=2.1485 sqrtA=5440.61 e=0.000146106 i0=0.963789 iode=0 X=4.61698e+06 Y=-2.91053e+07 Z=2.81403e+06 dts=1.52246e-05 10:48:49.122002 rtklib_pvt_gs.cc:1360] Galileo New Ephemeris record inserted in global map with TOW =594625, GALILEO Week Number =1333 and Ephemeris IOD = 104 10:48:49.133292 galileo_inav_message.cc:847] Page number = 2 10:48:49.133302 galileo_inav_message.cc:639] IOD_nav_2= 105 10:48:49.133306 galileo_inav_message.cc:642] OMEGA_0_2= 1.17356 10:48:49.133316 galileo_inav_message.cc:645] i_0_2= 0.96379 10:48:49.133319 galileo_inav_message.cc:648] omega_2= 0.723919 10:48:49.133322 galileo_inav_message.cc:651] iDot_2= 5.65381e-10 10:48:49.133325 galileo_inav_message.cc:653] flag_tow_set1 10:48:49.133334 galileo_telemetry_decoder_gs.cc:414] Galileo E1 CRC correct in channel 26 from satellite Galileo PRN E25 (Block FOC-FM16) 10:48:49.133339 galileo_inav_message.cc:227] Ephemeris (1, 2, 3, 4) have been received and belong to the same batch 10:48:49.133342 galileo_inav_message.cc:235] Batch number: 105 10:48:49.133461 rtklib_pvt_gs.cc:1360] Galileo New Ephemeris record inserted in global map with TOW =594625, GALILEO Week Number =1333 and Ephemeris IOD = 105 10:48:49.141060 rtklib_ephemeris.cc:823] Eph sat=84 time=594634 toe=594000 toc=594000 ttr=594625 week=2357 M0=2.22289 sqrtA=5440.61 e=0.000146106 i0=0.96379 iode=0 X=4.61698e+06 Y=-2.91053e+07 Z=2.81397e+06 dts=1.52246e-05 10:48:59.507434 galileo_telemetry_decoder_gs.cc:666] Galileo E5a CRC correct in channel 32 from satellite Galileo PRN E19 (Block IOV-FM3) with CN0=41.6421 dB-Hz 10:48:59.507483 rtklib_pvt_gs.cc:1422] New IONO record has arrived 10:48:59.507501 rtklib_pvt_gs.cc:1433] New UTC record has arrived 11:05:55.314313 rtklib_ephemeris.cc:823] Eph sat=84 time=595234 toe=594000 toc=594000 ttr=595195 week=2357 M0=2.22289 sqrtA=5440.61 e=0.000146106 i0=0.96379 iode=0 X=4.60193e+06 Y=-2.92262e+07 Z=1.01166e+06 dts=1.52248e-05 11:05:55.315913 galileo_inav_message.cc:847] Page number = 2 11:05:55.315922 galileo_inav_message.cc:639] IOD_nav_2= 106 11:05:55.315923 galileo_inav_message.cc:642] OMEGA_0_2= 1.17356 11:05:55.315930 galileo_inav_message.cc:645] i_0_2= 0.96379 11:05:55.315933 galileo_inav_message.cc:648] omega_2= 0.723919 11:05:55.315936 galileo_inav_message.cc:651] iDot_2= 5.65381e-10 11:05:55.315939 galileo_inav_message.cc:653] flag_tow_set1 11:05:55.315948 galileo_telemetry_decoder_gs.cc:414] Galileo E1 CRC correct in channel 26 from satellite Galileo PRN E25 (Block FOC-FM16) 11:05:55.315973 galileo_inav_message.cc:227] Ephemeris (1, 2, 3, 4) have been received and belong to the same batch 11:05:55.315975 galileo_inav_message.cc:235] Batch number: 106 11:05:55.341687 rtklib_ephemeris.cc:823] Eph sat=84 time=595234 toe=594600 toc=594600 ttr=595225 week=2357 M0=2.29727 sqrtA=5440.61 e=0.000146106 i0=0.96379 iode=0 X=4.60193e+06 Y=-2.92262e+07 Z=1.0116e+06 dts=1.52248e-05 11:14:33.558449 rtklib_ephemeris.cc:823] Eph sat=84 time=595534 toe=594600 toc=594600 ttr=595525 week=2357 M0=2.29727 sqrtA=5440.61 e=0.000146106 i0=0.96379 iode=0 X=4.58534e+06 Y=-2.92462e+07 Z=106464 dts=1.52249e-05

SV68:

10:34:34.561585 rtklib_ephemeris.cc:823] Eph sat=68 time=594126 toe=593400 toc=593400 ttr=594115 week=2357 M0=-0.109792 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.40187e+07 Y=-1.38893e+07 Z=-1.02826e+07 dts=-0.000812893 10:48:26.412761 rtklib_ephemeris.cc:823] Eph sat=68 time=594620 toe=593400 toc=593400 ttr=594565 week=2357 M0=-0.109792 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.44655e+07 Y=-1.40584e+07 Z=-8.90755e+06 dts=-0.0008129 10:48:26.435570 galileo_telemetry_decoder_gs.cc:666] Galileo E5a CRC correct in channel 34 from satellite Galileo PRN E09 (Block FOC-FM9) with CN0=42.5862 dB-Hz 10:48:26.435580 galileo_fnav_message.cc:323] Ephemeris (1, 2, 3) have been received and belong to the same batch 10:48:26.435581 galileo_fnav_message.cc:329] Batch number: 103 10:48:26.435627 rtklib_pvt_gs.cc:1360] Galileo New Ephemeris record inserted in global map with TOW =594570, GALILEO Week Number =1333 and Ephemeris IOD = 103 10:48:26.436972 rtklib_ephemeris.cc:823] Eph sat=68 time=594620 toe=593400 toc=594000 ttr=594570 week=2357 M0=-0.0354056 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.55106e+07 Y=-1.31532e+07 Z=-7.19355e+06 dts=-0.0008129 10:48:26.487505 rtklib_ephemeris.cc:823] Eph sat=68 time=594620 toe=593400 toc=594000 ttr=594570 week=2357 M0=-0.0354056 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.55107e+07 Y=-1.31532e+07 Z=-7.19349e+06 dts=-0.0008129 10:48:26.521703 rtklib_ephemeris.cc:823] Eph sat=68 time=594620 toe=593400 toc=594000 ttr=594570 week=2357 M0=-0.0354056 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.55107e+07 Y=-1.31532e+07 Z=-7.19343e+06 dts=-0.0008129 10:48:49.121876 galileo_inav_message.cc:847] Page number = 2 10:48:49.121886 galileo_inav_message.cc:639] IOD_nav_2= 104 10:48:49.121888 galileo_inav_message.cc:642] OMEGA_0_2= -0.925131 10:48:49.121896 galileo_inav_message.cc:645] i_0_2= 0.969422 10:48:49.121899 galileo_inav_message.cc:648] omega_2= -0.415212 10:48:49.121902 galileo_inav_message.cc:651] iDot_2= -3.94302e-10 10:48:49.121904 galileo_inav_message.cc:653] flag_tow_set1 10:48:49.121913 galileo_telemetry_decoder_gs.cc:414] Galileo E1 CRC correct in channel 24 from satellite Galileo PRN E09 (Block FOC-FM9) 10:48:49.121918 galileo_inav_message.cc:227] Ephemeris (1, 2, 3, 4) have been received and belong to the same batch 10:48:49.121920 galileo_inav_message.cc:235] Batch number: 104 10:48:49.122002 rtklib_pvt_gs.cc:1360] Galileo New Ephemeris record inserted in global map with TOW =594625, GALILEO Week Number =1333 and Ephemeris IOD = 104 10:48:49.141001 rtklib_ephemeris.cc:823] Eph sat=68 time=594634 toe=594000 toc=594000 ttr=594625 week=2357 M0=-0.0354056 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.44769e+07 Y=-1.4063e+07 Z=-8.86865e+06 dts=-0.0008129 11:05:32.501529 rtklib_ephemeris.cc:823] Eph sat=68 time=595220 toe=594000 toc=594000 ttr=595195 week=2357 M0=-0.0354056 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.49109e+07 Y=-1.42564e+07 Z=-7.1936e+06 dts=-0.000812909 11:05:32.512358 galileo_telemetry_decoder_gs.cc:666] Galileo E5a CRC correct in channel 34 from satellite Galileo PRN E09 (Block FOC-FM9) with CN0=42.8036 dB-Hz 11:05:32.512370 galileo_fnav_message.cc:323] Ephemeris (1, 2, 3) have been received and belong to the same batch 11:05:32.512373 galileo_fnav_message.cc:329] Batch number: 103 11:05:32.512429 rtklib_pvt_gs.cc:1360] Galileo New Ephemeris record inserted in global map with TOW =595170, GALILEO Week Number =1333 and Ephemeris IOD = 103 11:05:32.547634 rtklib_ephemeris.cc:823] Eph sat=68 time=595220 toe=594000 toc=594600 ttr=595170 week=2357 M0=0.0389804 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.58567e+07 Y=-1.33189e+07 Z=-5.43977e+06 dts=-0.000812909 11:05:55.314254 rtklib_ephemeris.cc:823] Eph sat=68 time=595234 toe=594000 toc=594600 ttr=595170 week=2357 M0=0.0389804 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.58634e+07 Y=-1.33225e+07 Z=-5.3991e+06 dts=-0.000812909 11:05:55.318538 galileo_inav_message.cc:847] Page number = 2 11:05:55.318544 galileo_inav_message.cc:639] IOD_nav_2= 105 11:05:55.318547 galileo_inav_message.cc:642] OMEGA_0_2= -0.925135 11:05:55.318552 galileo_inav_message.cc:645] i_0_2= 0.969422 11:05:55.318555 galileo_inav_message.cc:648] omega_2= -0.415212 11:05:55.318557 galileo_inav_message.cc:651] iDot_2= -3.94302e-10 11:05:55.318560 galileo_inav_message.cc:653] flag_tow_set1 11:05:55.318568 galileo_telemetry_decoder_gs.cc:414] Galileo E1 CRC correct in channel 24 from satellite Galileo PRN E09 (Block FOC-FM9) 11:05:55.318572 galileo_inav_message.cc:227] Ephemeris (1, 2, 3, 4) have been received and belong to the same batch 11:05:55.318574 galileo_inav_message.cc:235] Batch number: 105 11:05:55.318764 rtklib_pvt_gs.cc:1360] Galileo New Ephemeris record inserted in global map with TOW =595225, GALILEO Week Number =1333 and Ephemeris IOD = 105 11:05:55.341617 rtklib_ephemeris.cc:823] Eph sat=68 time=595234 toe=594600 toc=594600 ttr=595225 week=2357 M0=0.0389804 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.49199e+07 Y=-1.42608e+07 Z=-7.15362e+06 dts=-0.000812909 11:14:33.558389 rtklib_ephemeris.cc:823] Eph sat=68 time=595534 toe=594600 toc=594600 ttr=595525 week=2357 M0=0.0389804 sqrtA=5440.6 e=0.000366836 i0=0.969422 iode=0 X=2.51015e+07 Y=-1.43538e+07 Z=-6.27945e+06 dts=-0.000812913

In SV84 we can see that a new I/NAV message is recorded before toe and M0 being updated at the same time.
In SV68, a new F/NAV is recorded and only M0 is updated. Only when a new I/NAV message is recorded the toe parameter is updated and the satellite position is corrected.

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how can i use gnss-sdr with rtklib？