Solution Accuracy
NMEA
Multi-Vendor
- EPE - Accuracy Estimates - Horizontal and vertical accuracy estimates - probably 1-sigma
- GBS - GNSS Satellite Fault Detection - includes latitude, longitude, altitude errors (1-sigma)
- This message outputs the results of the “Receiver Autonomous Integrity Monitoring” algorithm (RAIM)
- GRS - GPS Range Residuals - includes residuals for up to 12 satellites
- GST - GNSS Pseudorange Noise Statistics - includes UERE, latitude, longitude, altitude errors (1-sigma)
Notes:
- EPE and GBS are only supported by some MediaTek chipsets, such as the MT3333.
- GRS and GST are supported by many / most MediaTek chipsets.
- EPE is not supported by UBX chipsets but the accuracy estimates can be found in PUBX,0.
- GBS, GST and GRS are all supported by the UBX chipsets.
NMEA 4.10
- GFA (TBC) - GNSS Fix Accuracy and Integrity - Supports Galileo and other GNSS. Different than the GST sentence
Vendor Specific
- PGLOR (Broadcom) - RMS (comparable to 1-sigma) - 68% of 1-dimension, 63% for 2-dimensions
- PGLOR,…,LSQ - Least squares - HErr, AltErr, HSpdErr, VSpdErr, TrkAngErr (RMS)
- PGLOR,…,STA - GNSS latitude/longitude status - VelTrkQual - [poor/good] velocity + [poor/good] track
- PGLOR,…,SPD - Speed status - includes cadance, etc.
- PGRME (Garmin) - Estimated Error Information - includes estimated horizontal position error (HPE) + vertical position error (VPE)
- PJLTS - Jackson Labs Time and 3D velocity - TBC
- Micro-JLT GNSSTM board - Jun 2023
- Includes speed accuracy estimate (cm/s)
- Survey modes have a variance of average position, suggesting standard deviation is also used internally
- See also XYZSPeed (speed accuracy) and PASHR (ROC) and GPS:DYNAMic:MODE (dynamic motion model for the Kalman filter)
- PSRFEPE (SiRF) - EHPE, EVPE, EHVE, EHE. According to gpsd, SiRF have never confirmed whether it is 1-sigma.
- PUBX,0 (x-box) - Position - probably 1-sigma
- includes hAcc, vAcc but no sAcc or cAcc