E Comparison Of RT-2 And RT-20
232 MiLLennium GPSCard SW Version 4.503/4.52 Command Descriptions Manual Rev 2
RT-2 Performance
The RT-2 software provides the accuracies shown in Table E-3 & Figure E-1 (static mode) and Table E-4 & Figure
E-2 (kinematic mode) for “typical” multipath, ionospheric, tropospheric, and ephemeris errors, where “typical” is
described as follows:
•A typical multipath environment would provide no carrier-phase double-difference multipath errors
greater than 2 cm or pseudorange double-difference multipath errors greater than 2 m on satellites at 11°
elevation or greater. For environments where there is greater multipath, please consult NovAtel Customer
Service.
•Typical unmodeled ionospheric, tropospheric and ephemeris errors must be within 2σ of their average
values, at a given elevation angle and baseline length. It is assumed that the tropospheric correction is
computed with standard atmospheric parameters. All performance specifications assume that at least 6
satellites above the mask angle (varies between 11 and 14 degrees) are being tracked on both L1 and L2.
In Tables E-3 and E-4, accuracy values refer to horizontal RMS error, and are based on matched positions. There
are no data delays for a matched log and therefore no need to add anything. The level of position accuracy at any
time will be reflected in the standard deviations output with the position.
Table E-3 RT-2 Performance: Static Mode
Table E-4 RT-2 Performance: Kinematic Mode
PRTK logs contain some error due to predictions from base station observations. The expected error of a PRTK
log will be that of the corresponding RTK log plus the appropriate error from Table E-5.
Table E-5 RT-2 Degradation With Respect To Data Delay ➀
See Section A.3, Page 65 for an overview of GPS positioning.
Baseline
length Time since L2 lock-on with at least
6 satellites above mask angle Horizontal accuracy at
the stated time Runs meeting the stated
accuracy at the stated time
< 10 km 70 seconds + 1.5 sec/km 2 cm + 0.5 ppm 75.0%
< 10 km 5 minutes 1 cm + 1 ppm 75.0%
< 15 km 4 minutes 5 cm 66.7%
< 25 km 7 minutes 7 cm 66.7%
< 35 km 10 minutes 35 cm 66.7%
< 35 km 30 minutes 25 cm 66.7%
Baseline
length Time since L2 lock-on with at least
6 satellites above mask angle Horizontal accuracy at
the stated time Runs meeting the stated
accuracy at the stated time
< 10 km 120 seconds + 1.5 sec/km 2 cm + 0.5 ppm 75.0%
< 15 km 8 minutes 8 cm 66.7%
< 25 km 14 minutes 10 cm 66. 7%
< 35 km 20 minutes 40 cm 66. 7%
< 35 km 60 minutes 25 cm 66.7%
Data Delay (sec) Distance (km) Accuracy (CEP)
0 - 2 1+1 cm/sec
2 - 7 1+2 cm/sec
7 - 30 1+5 cm/sec
>30 1single point or pseudorange differential positioning ➁
➀Mode = Static or Kinematic
➁After 30 seconds reverts to pseudorange positioning (single point or differential
depending on messages previously received from the base station).