Can't get better than RTK float with the Sparkfun LG290P GNSS RTK Breakout Module

GPS/GNSS
1

Hi All,

I have searched the GPS/GNSS Forum for an answer to my issue and have not able to find a solution.

Base Station: Sparkfun RTK Postcard/Portability Shield with L1/L2/L5 active antenna.
ZED-F9P UART3 RTCM3 Telemetry baud rate of 57,600.
Rover 1: Sparkfun ZED-F9P RTK Receiver with L1/L2 active antenna .
Rover 2: Sparkfun LG290P RTK GNSS Breakout Module L1/L2 active antenna.
LG290P GNSS RTK Breakout Module FW: LG290P03AANR01A05S
The baud rate for the LG290P RTCM3 Telemetry UART3 input is 57,600.

I decided to evaluate my Sparkfun RTK Postcard Base Station with the Sparkfun LG290P RTK GNSS Development Module that I plan to install on my Traxxas Rover.
I setup the RTK Postcard/Portability Shield Base Station in the driveway with a clear view of the sky, got a mean deviation of under 0.3 m after a 60 sec Survey-in, after which the RTCM3 transmissions began.
Then I powered up the Sparkfun ZED-F9P RTK Receiver that is presently on my Traxxas Rover, which had a clear view of the sky, and after less than five minutes I had a RTK Fix indication when the board RTK indicator quit flashing.
So I swapped out the ZED-F9P RTK Receiver with the Sparkfun LG290P RTK GNSS Breakout Module and could only get a RTK Float indication as the board RTK indicator kept flashing and never turned off to indicate a RTK Fix indication.
To verify this issue with the LG290P RTK GNSS Development Module, I took the LG290P RTK GNSS Development Module off the Traxxas Rover and hooked it up to a laptop outdoors and used the Quectel QGNSS app to verify that the LG290P RTK GNSS Development Module on the Rover was only getting a RTK Float indication, not a RTK Fix indication, and that was the case as the QGNSS Data View Quality Indicator was showing “Float RTK”.

Since my Sparkfun ZED-F9P RTK Receiver was able to reach RTK Fix using the same Sparkfun RTK Postcard/Portability Shield Base Station I am confident that the same RTCM3 messages should be being received by the LG290P RTK GNSS Development Module too.

Therefore I am presently at a loss as to how to troubleshoot this issue as it looks like I have the latest stable LG290P software version according to the Sparkfun GitHub.

Regards,

TCIII

2

Hi All,

After doing a lot of IoT searching, its seems that the LG290P RTK GNSS Development Module requires RTCM3-MSM4 messages on the UART3 input to achieve a RTK Fix indication when in the Rover mode.
I believe that my Sparkfun RTK Postcard/Portability Shield Base Station is only outputting RTCM3 messages.

Is this revelation correct and if so how to configure my Sparkfun RTK Postcard/Portability Shield Base Station for RTCM3-MSM4 message output on UART3?

Further research indicates that the UART3 output of the LG290P can be configured directly for RTCM3-MSM4 output by sending the following commands, using QGNSS, to the LG290P module:

  • Stop the module: Command: $PQTMGNSSSTOP*09
  • The command $PQTMSETTING,W,MODE,1,0,3*6D puts the receiver into a mode where it will only output MSM4 and RTCMv3 1005 messages.
  • Save the new settings to the non-volatile memory by sending $PQTMSAVEPAR*5A.
  • Reboot the module by sending $PQTMSRR*4B.

On the other hand, I have tried using the RTK Everywhere serial user interface with PuTTY, but the “Configure GNSS Messages” Menu item only opens up a menu that allows “Set Base RTCM Messages” which allows the selection of available RTCM3 messages, but not the configuration of those messages.

So far I am hesitant to use the QGNSS app to change the UART3 output configuration as I am not quite sure of the impact on the installed RTK Everywhere firmware.

Regards,
TCIII

3

Hi All,

The solution to my issue is becoming more convoluted as I have come upon another solution to configure the Sparkfun RTK Postcard’s LG290P to output RTCM3-MSM4 messages on UART3:

  • Stop the module: Command: $PQTMGNSSSTOP*09

  • Set UART3 to output only RTCM3 messages: Command: $PQTMCFGPROT,W,3,0,4*41.

  • Set the MSM4 output rate: Command: $PQTMCFGMSGRATE,W,RTCM3,1074,1*61

  • Save parameters: Send the command $PQTMSAVEPAR*5A. The module will respond with $PQTMSAVEPAR,OK*4E.

  • Reboot the module: Send the command $PQTMSRR*4B. The LG290P will then restart with the new settings.

Comments please.

Regards,
TCIII

4

TC third, I don’t understand where you got these commands from…you should strictly refer to the manual: Resources - SparkFun LG290P Quadband GNSS RTK Breakout Hookup Guide

However, I thought it would be better to set the breakout as the base and the postcard as the rover.I tested the breakout at 5700 baud but you have to use MSM7 & ephemerides.
Using the protocol the commands to set the base are these in order
For the postcard just reset it and it is already ready.
base_mode for breakout:

$PQTMRESTOREPAR*13   Clear all data to default
$PQTMGNSSSTOP*09
$PQTMCFGRCVRMODE,W,2*29   # set receiver to base mode
Set the base in ecef -->   $PQTMCFGSVIN,W,2,0,0,x,y,z*<Checksum>   <-- need to compile and run the checksum
$PQTMCFGSVIN,R*26 check if ecef base is correct (U can ask in postcard sending the above command and copy the coord)
$PQTMCFGRTCM,W,7,0,15,07,06,2,30*36
$PQTMSAVEPAR*5A
$PQTMSRR*4B
$PQTMGNSSSTOP*09
$PQTMCFGMSGRATE,W,1,3,RTCM3-1019,1*56
$PQTMCFGMSGRATE,W,1,3,RTCM3-1020,1*5C
$PQTMCFGMSGRATE,W,1,3,RTCM3-1041,1*5B
$PQTMCFGMSGRATE,W,1,3,RTCM3-1042,1*58
$PQTMCFGMSGRATE,W,1,3,RTCM3-1044,1*5E
$PQTMCFGMSGRATE,W,1,3,RTCM3-1046,1*5C
$PQTMSAVEPAR*5A
$PQTMSRR*4B
$PQTMCFGMSGRATE,W,1,3,RTCM3-1033,0*5F
$PQTMCFGUART,W,3,57600*34
$PQTMSAVEPAR*5A
$PQTMSRR*4B

Anyway if U would try on the postcard first, set as follows for the base mode
not rover…

$PQTMCFGRTCM,W,7,0,15,07,06,2,30*36
$PQTMSAVEPAR*5A
$PQTMSRR*4B
$PQTMGNSSSTOP*09
$PQTMCFGMSGRATE,W,1,3,RTCM3-1019,1*56
$PQTMCFGMSGRATE,W,1,3,RTCM3-1020,1*5C
$PQTMCFGMSGRATE,W,1,3,RTCM3-1041,1*5B
$PQTMCFGMSGRATE,W,1,3,RTCM3-1042,1*58
$PQTMCFGMSGRATE,W,1,3,RTCM3-1044,1*5E
$PQTMCFGMSGRATE,W,1,3,RTCM3-1046,1*5C
$PQTMSAVEPAR*5A
$PQTMSRR*4B
$PQTMCFGMSGRATE,W,1,3,RTCM3-1033,0*5F
$PQTMSAVEPAR*5A
$PQTMSRR*4B

as you notice, you have to save and reset several times
Regards

5

@bamarcant,

Thanks for the response, much appreciated.

Unfortunately due to physical limitations, there is no way for me to swap the LG290P GNSS RTK Breakout Module for the RTK Postcard and vice versa.

I assume that the second set of commands is an attempt to get the RTK Postcard/Portability Shield, which is presently the Base Station, to send the correct RTCM3-MSM7 & ephemerides messages to the LG290P GNSS RTK Breakout Module which is presently the Rover?

If I do reconfigure the RTK Postcard/Portability Shield to send the correct RTCM3-MSM7 & ephemerides messages, will there be any issues using the RTK Postcard/Portability Shield with the Sparkfun ZED-F9P RTK GNSS Breakout Module as the Rover?

Regards,
TCIII

6

The MSM7’s are more complete and ublox and other receivers also benefit, but you have to wait and change the firmware for the postcard RTK_Everywhere
when ready for msm7.I don’t know if the manual setup revert to default once reboot…