Ardupilot Integration Issues

Hello everyone,

I was hoping someone would be able to take a look at this issue I am having.

I recently purchased the Reach M+ UAV RTK kit and have set it up as follows:

  1. Connected the LoRa Radio to the Reach M+ RTK GNSS Module (S2 Port) using the provided 7 pin connector

  2. Connected the Reach M+ RTK GNSS Module (S1 Port) to a Cube Orange controller (GPS2/Serial4 Port) as follows:

     a. Pin 1 on M+ to Pin 6 on Cube (Ground - Ground)
     b. Pin 4 on M+ to Pin 3 on Cube (TX - RX)
     c. Pin 5 on M+ to Pin 2 on Cube (RX - TX)
    

    The M+ Module is powered from an external, power source through the USB input.

  3. GNSS Antennae is connected to the M+ Module and is placed on a 75mm x 90mm steel plate, roughly 250mm above the top surface fo the drone.

Reach RS+ Module Setup:

  1. GNSS Settings:
    a. Positioning Mode: Kinematic
    b. GPS AR mode: Fix-and-Hold
    c. GLONASS AR Mode: On
    d. GNSS Selected: GPS, GLONASS,GALILEO, SBAS, QZSS
    e. Update Rate: 5Hz
  2. Correction Input: LoRa
    a. Frequency: 902.5 MHz
    b. Output Power: 20dBm
    c. Air Data Rate: 9.11 kb/s
  3. Correction Output: Off
  4. Position Streaming
    a. Output 1: UART, 38400 Baud, NMEA
    NMEA Settings:
    Talker ID: GN
    Message type: All set to 1 Hz
    b. Output 2: Off
  5. Base Mode:
    a. Base Coordinates: Average Single, 5 min accumulation time
    b. RTCM3 messages:
    1002 - 1 Hz
    1010 - 0.5 Hz
    1097 - 0.5 Hz
    1107 - 0.5 Hz
    1117 - 1 Hz
    1127 - 0.5 Hz
    1006 - 0.1 Hz

Reach M+ RTK GNSS Module Setup:

  1. GNSS Settings:
    a. Positioning Mode: Static
    b. GPS AR mode: Fix-and-Hold
    c. GLONASS AR Mode: On
    d. GNSS Selected: GPS, GLONASS,GALILEO, SBAS, QZSS
    e. Update Rate: 5Hz
  2. Correction Input: Off
  3. Correction Output: LoRa
    a. Frequency: 902.5 MHz
    b. Output Power: 20dBm
    c. Air Data Rate: 9.11 kb/s
  4. Position Streaming
    a. Output 1: Off
    b. Output 2: Off
  5. Base Mode:
    a. Base Coordinates: Average Single, 5 min accumulation time
    b. RTCM3 messages:
    1002 - 1 Hz
    1010 - 0.5 Hz
    1097 - 0.5 Hz
    1107 - 0.5 Hz
    1117 - 1 Hz
    1127 - 0.5 Hz
    1006 - 0.1 Hz

ArduPilot Setup:

  1. GPS_TYPE2 = 5 (NMEA)
  2. GPS_AUTO_SWITCH = 1
  3. GPS_INJECT_TO = 1
  4. SERIAL4_PROTOCOL = 5 (GPS)
  5. SERIAL4_BAUD = 38

The system seems to be working, the M+ Module receives corrections and is able to get down to a FIX status.

The issue that I am running into is that I cannot arm the drone when on Position Hold and I constantly get either a High HDOP error or GPS Unhealthy error which does not allow me to arm. I Have triple checked all of my wiring and settings and I cannot figure out what the issue is.

Please let me know if anyone has any ideas or needs any additional information.

Thanks,
David

Hi David,

Welcome to our community!

In most cases, such errors are shown if the receiver tracks an insufficient number of satellites for the precise position calculation. However, you’ve noted that your Reach M+ got Fix. Could you please clarify whether the Fix solution is stable and how big is HDOP? You can also record the following logs on the base and rover for 10-15 minutes so that I can take a closer look at the satellite signals reception:

  • raw data, base correction, and position logs on the rover

  • raw data log on the base

As I see, the Position streaming is enabled on Reach RS+, while the Correction output is turned off. So, it looks as if the settings for Reach M+ and Reach RS+ are swapped. Could you please check it?

Hi Kseniia,

I will get the logs for you today.

In regards to the settings for the RS+ and M+, I think I accidentally switched the titles when I was typing up my original post. The M+ is the one with Position Streaming enabled and the RS+ is the one with the Correction Output set to the LoRa Radio.

Attached are the log files for both the RS+ and the M+ Modules. We started up both modules and let them start recording information and about 10 or so minutes in we turned the drone on. We were still getting the same issue with the GPS unhealthy error. Let me know if there is any other information that I can provide.
Logs.zip (7.0 MB)

Hi David,

Thanks for sharing the logs! I’ll check them and write back.