Mavlink Telemetry problem. Parameter upload is very slow

Thank you! I will do so. Otherwise which GCS is prefered for quadcopter operations QGroundControl or MissionPlanner?

mission planner is more feature rich but qground control is sleeker and more modern just depends on what you prefer.

Make sure you are using the most recent beta version of Mission Planner and 4.1.2 firmware on your vehicle. That may help.

Using ctrl+T is a workaround, i think he should find the reason why it takes 10 minutes to download params, it should take few seconds.

A proper configured RFD900ux should be very fast.

Take a look at RFD900 and RFD868 threads in this forum. Mine run great even with extra Yappu telemetry and AES 256 bit encryption!

Make sure Tx and Rx are connected properly on both radio’s, I had a similar issue: RFD868+ "getting params 1" never finishes? (Solved) - #6 by Graham_Dyer
Otherwise try enable rts/cts on the radio or also try change sr1_params to say 100.

You mean that RFD900 works?? Wow i wouldn’t have ever imagined!!!
I must remember to never take the obvious for granted.

hello, have you check the Stream rate parameters yet? Please post the param file or .bin log file, so I can check these. However, it guess it may be a problem.

Hi! Thank you for help! Could you please explain what do you mean on Stream rate parameters. I have been looking for them in ardupilot documentation but could not find.

Hi! Electronically it’s fine, I can see the rx and tx bytes are also incrementing. But the speed…

Here is the documentation:

Here is parameters documentation:

Google “arducopter stream rate parameters” gave me those links. :stuck_out_tongue:

Look for a param named:

SRX_PARAMS (X is the serial port you are using for telemetry).

You can try increasing it to 50 and see if it makes any difference.

For example if you have telemetry on serial 1 look for:


and increase it to 50.

You can find all params in MissionPlanner---->config---->full parameter tree (scroll down to SR0 SR1 SR2…)

Hope it is clearer than some “i have it longer than yours kind of answers” :slight_smile:

Thanks it’s clear now! I’ve tried set SR1_PARAMS to 50 but no effect. I use the TELEM1 connector with factory cable to interfacing cube orange with RFD900 (precisely RFD868ux). Based on the manual it is SERIAL 1.

Ok thanks for being so detailed I’ll try to following you :slight_smile:
Here are my relevant parameters below(I still have connection it works but very slow). I’m trying two different options as you will see. I also made a try with crossfire from my FPV drones with micro TX v2 and nano RX but it was also slow.


Setup no. 1.

GROUND: TX MOD (a factory made RFD900based radio module inserted to my Radiomaster TX16S connecting to PC via WIFI in AP mode using UDP protocol on port 14550)

result 1:image
Setup no. 2.

UAV :same settings
Ground: RFD868ux modem with usb serial cable using serial port in mission planner.

result 2: almost the same

Hi sadly the SR1_PARAMS setting did not solve the problem. Here is my settings filerfd900_211209.param (21.8 KB)

I think I make a chance with software upgrade now. It’s the next step.


  1. change serial1_protocol=2 (Mavlink2), since 4.1.x uses mavftp to transfer params faster
  2. change BRD_SER1_RTSCTS=0
  3. Do you provide “clean” external power to Remote Radio? if not, please add a dedicated BEC with some shielding
  4. Lower your air_speed to 64 to both radios
  5. change duty_cycle to 100 to remote radio
  6. change SR1_PARAMS = 10
  7. ensure your antennas are at 90degr for both sides for diversity to work
  8. If you use the monopole antennas on the airside, ensure 90 deg placement and proper usage of some duct tape aluminum foil to act as ground plane.

If your hardware works as expected, then the above mentioned params will most propably fix your problems

Hi thanks for your reply!
Meanwhile I made some changes, now it’s about 0.750-1 kb/s :grinning: but I will make some tuning based on your advices.

  1. serial1_protocol=2 it’s done
  2. change BRD_SER1_RTSCTS=0 Do you think it’s not neccesary to use RTS/CTS (they are enabled on both radios now)?
  3. Do you provide “clean” external power - I will try it!
  4. Lower your air_speed to 64 to both radios - Now it is 100 it was 64 but I will try again with 64.
  5. change duty_cycle to 100 - when I change to set the duty cycle from 10 to anything else it does not connect. or you mean 10 = 100% ?
  6. change SR1_PARAMS = 10 It is now 50 I will try it.
  7. ensure your antennas are at 90degr for both sides for diversity to work - it’s done
  8. If you use the monopole antennas on the airside, ensure 90 deg placement and proper usage of some duct tape aluminum foil to act as ground plane. - seems to be a good idea thanks
  1. yes, it will propably cause more issues
  2. Mandatory!!! Twist the cables and might use ferite
  3. Mandatory
  4. Correct i mean 100%
  5. 50 is overkill,
  6. google the Lamda for 868MHz and apply the correct area needed (no less no more), less wont do anything, more might make it more prone to noise. Rule of thump is minimum 1/4 wave length radius (about 3inch radius circle for 868)

I use these settings with the RFD900 and with TXMODv2, you have to set your SERIAL1_BAUD=115
RFD868 should work the same as the 900’s. Duty Cycle should definitely be 100 unless there’s a restriction in your region.

I also use SBUS for the RC control via TXMOD (GPO1_1 SBUSIN and GPO1_1 SBUSOUT), not shown in the above settings. It’s much better than PPM (the ordinary R/CIN and R/COUT)
You can use RTS/CTS after you’ve got everything working well with them disabled.