How to “Fine Tune” Frequency T16 TX16S Multi-Protocol Module

If you are getting bad range or unexplained failsafe from your Jumper T16 or Radiomaster TX16S when flying with the multi-protocol module, the problem could be fixed by frequency fine tuning. Here I will show you how to fine tune frequency setting in the radio.

Go to “Model Setup”, scroll down to “Internal RF”, you should find the option “RF Freq. Fine Tune”. Default is 0, and you can change it between -50 and 50.

Method 1

Enable “Low Power Mode” option under “Internal RF” in the model setup page. (Remember to disable it after you finish fine-tuning frequency)

Place your quad a couple of meters away from your radio.

Decrease “RF Freq. Fine Tune” until you get a failsafe (warning from radio). Confirm it by flipping the arm switch, make sure you remove all the props first. The arm switch shouldn’t arm the quad when signal is lost, if it does then keep decreasing it until it won’t arm anymore.

Write down this number.

Now increase “RF Freq. Fine Tune”, signal will come back, but if you keep going, you will get another failsafe. Again, confirm with arm switch.

Write down this number.

Now the middle of these two numbers is what you want. Simply add the two numbers and divide by two.

For example, if I had -39 and 45, (-39+45)/2 = 6/2 = 3

Now, disable “Low Power Mode”.

Method 2

Place your quad at a distance, e.g. 50 meters away. Change tuning, and check RSSI (next to “RF Freq. Fine Tune”), find the number that gives you the highest RSSI.

Why this is needed?

I think it’s just the downside of having multiple protocols. Jumper explains why this is required:

Original FrSky, Futaba, Corona Hitec, and HoTT receivers have been frequency-tuned by the manufacturer at the factory. Because of variations in the oscillator crystals used in multiprotocol modules, it is necessary to fine-tune the module to match the manufacturer frequencies.

‘Compatible’ receivers suffer the same variation in crystal oscillators as multiprotocol modules but have to be compatible with genuine (manufacturer-tuned) transmitters so they will typically have auto-tuning built-in, and will self-tune to the radio’s frequency when they are bound.

7 thoughts on “How to “Fine Tune” Frequency T16 TX16S Multi-Protocol Module

  1. Alan

    Hi Oscar, I understand ther is a config file which can be written to force the fine tune into certain offsets. Now this would handy if the module was used in different transmitters. I have been reading this on github, but there aren’t any examples on how this done in plan English(a copy of the config.h file and where to place it),any help would be appreciated

    Reply
  2. Fenrir

    So this value is different for every mutliprotocol module and different for every module and receiver combination, where the receiver is from a different manufacturer? Or does it vary based on the protocol too? (D8, D16, FCC vs. LBT)

    I think this is important to add because I tuned mine for FrSky D16, but then got really dangerous corrupted packets on a jumper receiver that caused the quad to go into a deathroll without signal loss. Since I retuned for the Jumper RX it was fine.

    Reply
  3. Fenrir

    You can read it from the RSSI value in Betaflight or from the OSD. The XM+ can be flashed with firmware that outputs RSSI always on channel 8 or channel 16, that’s what the firmware labeled RSSI is for. I believe there is also an RSSI pad you can solder to.

    Reply
  4. Ajaxdima

    Hello, for method 1 how much is best to put the quad far from the ground and from the transmitter? Thank you Oscar for all your work!

    Reply

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