neogps and ublox (fix.lat_err_cm)

  • Sorry for cross-posting. I tried posting this question to the devices forum, but got some strange responses (asking me why I'm even trying to use positional error data, or asking me for code examples when I'm clearly just trying to get an integer value off a data structure.)

I noticed that /dev posts here, so I'm hoping he can see this message....


Hi folks,

I'm currently using NeoGPS with a ublox 8 board with Arduino Mega 2560. Everything works great except for the following:

fix.lat_err_cm, fix.lon_err_cm and fix.alt_err_cm, in integer centimeters
fix.spd_err_mmps, in integer mm/s
fix.hdg_errE5, in integer degrees * 100000
fix.time_err_ns, in integer nanoseconds

all the values above are returned as an integer value of "0".

Here are the my flags in ubx_cfg.h:

#define UBLOX_PARSE_STATUS
#define UBLOX_PARSE_TIMEGPS
#define UBLOX_PARSE_TIMEUTC
#define UBLOX_PARSE_POSLLH
//#define UBLOX_PARSE_DOP
//#define UBLOX_PARSE_PVT
#define UBLOX_PARSE_VELNED
//#define UBLOX_PARSE_SVINFO
//#define UBLOX_PARSE_CFGNAV5
//#define UBLOX_PARSE_MONVER
//#define UBLOX_PARSE_HNR_PVT

Here are the flags in my NMEAGPS_cfg.h:

#define NMEAGPS_PARSE_GGA
//#define NMEAGPS_PARSE_GLL
//#define NMEAGPS_PARSE_GSA
#define NMEAGPS_PARSE_GSV
//#define NMEAGPS_PARSE_GST
#define NMEAGPS_PARSE_RMC
#define NMEAGPS_PARSE_VTG
//#define NMEAGPS_PARSE_ZDA
#define NMEAGPS_PARSE_SATELLITES
#define NMEAGPS_PARSE_SATELLITE_INFO
#define GPS_FIX_LOCATION_DMS

Does anyone know if there's a special message I have to enable on my ublox module (such as RXM, SEC, TIM, NAV or MON) or some combination of flags I have to enable to get the positional accuracy / error values I mentioned to have meaningful values?

Post complete code!

froggg:
I tried posting this question to the devices forum, but got some strange responses (asking me why I'm even trying to use positional error data, or asking me for code examples ..........

I noticed that /dev posts here, so I'm hoping he can see this message....

/dev has not posted on here for almost a year.

/dev used to answer questions about the neogps library, but no longer, so you are stuck with the rest of the volunteers.

Apologies for trying to help.

Found the solution!

GST messages have to be enabled in NMEAGPS_cfg.h

In addition, the uBlox module must have GST messages enabled (which are disabled by default.) Make sure that you view the messages in uCenter to verify that you have the correct sub-message enabled.

Once these two are complete, then the lat, long, and altitude errors come through.