Issue with Receiving RTCM Corrections on Quectel LC86L Module

IoT Modules GNSS Module
1

Hello everyone,

I am using the Quectel LC86L module and facing issues receiving RTCM corrections. Here are the details of my setup:

  1. Hardware Connection:
  • RX of GNSS connected to TX of FTDI.
  • TX of GNSS connected to RX of FTDI.
  • GND of GNSS connected to GND of FTDI.
  • VCC of GNSS connected to a suitable power supply.
  1. Module Configuration: I have configured the GNSS module to receive RTCM with the following PMTK commands:
    $PMTK251,1152001F # Change baud rate to 115200
    $PMTK301,1    2D\r\n # Set to receive RTCM
  2. Using STRSVR (RTKLIB):
    I am using STRSVR to receive RTCM corrections from the NTRIP server and send them to the serial port.
    2024/08/06 09:37:08 [-C—] 0 B 0 bps
    2024/08/06 09:37:13 [CC—] 5730 B 8757 bps (0) 192.148.213.42/COBA3M
    2024/08/06 09:37:18 [CC—] 11202 B 8738 bps (0) 192.148.213.42/COBA3M
    2024/08/06 09:37:23 [CC—] 16817 B 4383 bps (0) 192.148.213.42/COBA3M
    2024/08/06 09:37:28 [CC—] 22289 B 8696 bps (0) 192.148.213.42/COBA3M
    2024/08/06 09:37:33 [CC—] 26800 B 8729 bps (0) 192.148.213.42/COBA3M
    2024/08/06 09:37:38 [CC—] 33376 B 4348 bps (0) 192.148.213.42/COBA3M
    2024/08/06 09:37:43 [CC—] 38985 B 8720 bps (0) 192.148.213.42/COBA3M
    2024/08/06 09:37:48 [CC—] 44469 B 8744 bps (0) 192.148.213.42/COBA3M
    Despite following these steps, the NMEA sentences do not show that the module is using differential corrections (DGPS). The quality of position field in the GGA sentences remains 1.

Could anyone help me identify what might be wrong with my configuration or suggest additional steps to resolve this issue?

Thank you in advance for your help!

2

Hi @josetemero

  1. Confirm that all commands have been sent successfully and the module has responded. Send “$PMTK301,12D" and the response is "$PMTK001,301,332”.
  2. How far is the base station you are using from you? It is necessary to ensure that the base station is no more than 10Km away from the module. The closer the distance between the module and the base station, the better the test effect.
  3. Is the RTCM data format you injected RTCM2.x or RTCM3.x? LC86L only supports RTCM2.x data.
3

Hi @george.gao

Thank you for your response.

  1. Command Confirmation: I have sent the command $PMTK301,1*2D and received the response $PMTK001,301,3*32, confirming that the command has been successfully sent and acknowledged by the module.
  2. Base Station Distance: The base station I am using is approximately 6 km away from my module.
  3. RTCM Data Format: I am injecting RTCM data in the format 2.3, which is supported by the LC86L module.

Additionally, when I open the USB port in SUSterm, I receive the NMEA GGA messagges with quality=1.
I have set the baud rate to 115200 as specified in the protocol specification.
This is my BKG configuration:

BKG_configuration
BKG_configuration1589×445 56.1 KB

Thank you for your assistance.

4

Hi @josetemero

  1. Please use the “$PQVERNO,R*3F” command to check the version of the module and let me know.
  2. Can you provide me with a copy of the RTCM data you imported into the module so I can verify it?
  3. Please provide your email address. If your version is not the latest, I will send you the latest software version via email.
5

Hi @george.gao
Thank you for your assistance. I have executed the command $PQVERNO,R*3F and received the following response:
$PQVERNO,R,LC86LICNR11A01S,2023/01/11,02:14*64
Additionally, I have captured the RTCM data as requested. Please find the raw RTCM data attached to this email. The data was captured directly from the stream that I have been using in my tests.

Please let me know if the version of the firmware I am using is the latest, or if an update is required. If a firmware update is necessary, I would appreciate it if you could send the latest version to my email address (I will leave my email address in a personal message as the forum does not allow me to include it here).

Thank you again for your support. I look forward to your guidance on the next steps.
RTCMdataRaw.zip (463.1 KB)

6

Hi @josetemero
I parsed the RTCM message you provided and found no problem. I have already raised the issue with my internal software colleagues and they need to arrange internal testing and verification, which may not be done quickly. But I will let you know as soon as possible if there is a result.

7

Hi @josetemero
Can you help me capture the debug log?
The operation is as follows:

  1. $PMTK251,921600*14 //Change the baud rate to 921600bps
  2. $PMTK299,1*2D //Open the debug log
  3. Restart the module
  4. Inject RTCM data and start capturing log
    You need to save the log output by the module and the RTCM data injected by the differential station, thank you.