I have been experimenting with the LC29HEA as a RTK GNSS receiver for my drone and have been unsuccessful to achieve stable flight using this device. After considerable research it appears the LC29H is not considered suitable for use on areal drones. From my experience the problem appears to be because the current firmware used in the LC29HEA outputs position data in ASCII NMEA 01832 format which is too bulky and slow for update frequencies of 10Hz required by most Flight Controllers (Ardupilot & PX4). I have found out that almost all RTK units used on drones use a faster binary message format(ie u-blox). I understand earlier versions of the LC29H firmware were able to output position data in MTK bit format which is supported by Ardupilot/PX4 and could be activated by $PAIR862 but this has now been removed from later versions. If the MTK output was a really MTK is it possible someone can give me copy of the last firmware with that functionality. Better still, is it possible Quectel can reactivate this function in a new firmware version ?
Hi @aluna ,
The LC29H (EA) supports a high-precision RTK update rate of 10 Hz by default (with a maximum of 10 Hz supported). To achieve stable 10 Hz performance without data loss, the documentation provides specific requirements:
- Baud Rate: It is highly recommended to set the UART baud rate to 460800 bps or higher. Messages may be lost if the baud rate is below 460800 bps at a 10 Hz output frequency.
- Message Filtering: When the output frequency is set to be greater than 1 Hz, the module is designed to only output RMC and GGA messages at that high frequency. Satellite-specific messages like GSA and GSV will automatically maintain a 1 Hz frequency to reduce bulk and prevent bandwidth issues.
Can you share the details of the current firmware version?
Best Regards.
Thankyou Mohamad, I think your email has helped me identify the problem. I believe the drone FC firmware PX4 and Ardupilot both require the GSA and GSV messages. So even though the RMC and GGA messages are set to 10Hz the FC is effectively throttle by the 1Hz to decode the GSA and GSV messages, The FC requires a minimum frequency of 5Hz to maintain stable flight (10Hz is better).
I am using LC29HEANR11A04S_RSA firmware. It would be very advantageous if this could be upgraded to send GSA and GSV also at 10Hz and would open the market to many drone enthusiasts if this is really the issue.
Hello Richard, @aluna
Purtroppo hai riaperto una questione che si è infranta con la prova del loiter_mode; c’era grande entusiasmo…
The module can output raw data, but the matter is that nobody has a decent parser,
there are in “Airoha_IoT_SDK_for_GNSS_Developers_Guide” & “Airoha_IoT_SDK_Location_Raw_Measurement_User_Guide” uncensored but unobtainable!
U can enable $PAIR830,2*2F not 862
and only read once the PVT & Heading by $PAIR031*38 & $PAIR036*3F
U can also enable proprietary data by $PAIR100,1,1*3B but the focus is on PAIR120 limited by firmware…
Hope U can investigate further.
Here bin data of 10Hz raw_data & proprietary sentences and only nmea_GGA
Regards
Thanks this interesting. I can now get some raw data out of the LC29H but it is going to be quite a task for me to workout what it is and if it is suitable for Ardupilot. Documentation is limited !