Dgps dgnss

Reach Module / M+ / M2 RTK / PPK configuration
1

In ReachView, how can I tell if my position is DGPS? My understanding is the only position types are single, float, and fix? I can look for the SBAS PRNs in the status page or in the NMEA GGA string for fix type but it seems it should be more obvious.

2

DGPS is an acronym for a non-RTK systems that have an accuracy of near 10 cm.

The Reach GNSS RTK receiver has better than 2 cm accuracy when you have a Fix.

3

Thanks for your reply. Yes, I’m familiar with RTK. Let my try and rephrase. My question is, given single positioning mode (no RTK), does Reach notify me when SBAS corrections are being applied? Even RTKLIB identifies DGPS as a positioning mode. From the RTKLIB docs, “It supports various positioning modes with GNSS for both real‐time‐ and post‐processing:
Single, DGPS/DGNSS, Kinematic, Static, Moving‐Baseline, Fixed, PPP‐Kinematic, PPP‐Static and PPP‐Fixed.”

4

I’m not 100% Sure on this - but where ReachView is set to Kinematic mode it probably will not show you DGPS results. It may be filtering them out, or assuming only autonomous (single), float, fix possibilities.

If you’re set to Single Mode you may see the DGPS from ReachView in an output NMEA stream.

Rather than look for the PRN values, I would check out the NMEA output stream for $GPGGA. It displays the current solution type as well.

 $GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47

Where:
     GGA          Global Positioning System Fix Data
     123519       Fix taken at 12:35:19 UTC
     4807.038,N   Latitude 48 deg 07.038' N
     01131.000,E  Longitude 11 deg 31.000' E
     1            Fix quality: 0 = invalid
                               1 = GPS fix (SPS)
                               2 = DGPS fix
                               3 = PPS fix
			       4 = Real Time Kinematic
			       5 = Float RTK
                               6 = estimated (dead reckoning) (2.3 feature)
			       7 = Manual input mode
			       8 = Simulation mode
     08           Number of satellites being tracked
     0.9          Horizontal dilution of position
     545.4,M      Altitude, Meters, above mean sea level
     46.9,M       Height of geoid (mean sea level) above WGS84
                      ellipsoid
     (empty field) time in seconds since last DGPS update
     (empty field) DGPS station ID number
     *47          the checksum data, always begins with *

I think searching the GGA output would be quicker than scanning the PRN values. Though if it doesn’t display DGPS at all, I would search for the PRNs.

Hopefully the GGA search will speed things up for you!

1 Like
5

I will look at GGA and see if SBAS corrections are taking place. Thx.

6

@igor.vereninov @egor.fedorov Can one of you provide some insight? Is a DGPS solution possible with Reach?

7

savvy0816

Is a DGPS solution possible with Reach? Yes and No. DGPS is available in the ublox NeoM8T.

Below is the NMEA GGA message with WAAS enabled and a DGPS solution. To get this open u-center and open a network connection tcp://192.168.x.xx:2000. u-center will connect but EMLID has turned off a bunch of messages so nothing appears on the screen. Open the messages view goto UBX CFG GNSS to enable the SBAS sats and UBX CFG SBAS to enable DGPS. Check the NMEA GGA message (it takes a couple of minutes for the solution status to change). If you turn off the REACH or change any of the receiver parameters using ReachView the configuration returns to the EMLID defaults.

$GNGGA,201517.00,6109.94962,N,14950.69479,W,2,12,0.59,45.6,M,11.3,M,0000*6A

I am not sure about this but it seems the DGPS solutions are only available in u-center. The Reach is doing its own processing through RTKLib so the NMEA GGA string returns solution status 1 when the u-center reports status 2.