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.
Do I Need Frequency Fine Tune?
If you see this “Fine Tune” option, you should do it regardless for optimal range. If you don’t see this option, it means the protocol you are using does not require frequency fine tune.
Protocol that requires fine tuning are:
- Frsky D (e.g. Frsky D4R, D8R)
- Frsky X (e.g. Frsky X4R, XSR, XM+)
- Frsky V (e.g. Frsky V8R4, V8FR)
- S-FHSS (Futaba S-FHSS)
- Any other protocols that uses CC2500 RF Chip to emulate XN297
Steps to Fine Tune Frequency
Place your quad a couple of meters away from your radio.
You will need to adjust “RF Freq. Fine Tune“, and it will have an impact on “RSSI: x dB” next to it, which is a signal strength indicator.
Increase “RF Freq. Fine Tune” until RSSI drops to 0 dB. Write down that number.
Now decrease “RF Freq. Fine Tune“, signal will come back, but if you keep going, you will get another RSSI drop. Again, write down this number.
The middle of these two numbers is what you want to set “RF Freq. Fine Tune” to. How to work it out? Simply add the two numbers together and divide by two.
For example, if I had 24 and -48, it would be (24-48)/2 = -12
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.