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2.4GHz radio control protocol?

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deephaven:
I notice that a lot of radio control model aircraft etc now use 2.4GHz rather than the lower frequencies. Does anyone know if they use a standard protocol like Zigbee or similar or is there one dedicated to that application? Just curious.

kaptain_zero:
They still use PCM (pulse code modluation) but proprietary spread spectrum transmissions. No two manufacturers equipment is compatible. Notable exception is JR/Spektrum who share their technology as far as I know.

Regards

Christian 

deephaven:
Thanks Christian.

RCMR:
As Christian has said, there is no "standard" for the protocols used now that RC gear has gone to 2.4GHz.

In the old FM ("longwire) days, there was a defacto standard that involved the use of a pulsetrain (one for each channel) with a median width of 1.5mS and a variance of (usually) +/- 500nS.  Each frame (series of channel-pulses) was demarked by a sync pulse that was generally 3mS or longer, depending on the number of channels encoded.  The standard frame-rate was around 20mS (50 fps).

Now however, each manufacturer has come up with their own method for encoding the channel positions, each striving to produce the lowest-latency and highest redundancy.

None of these protocols are well documented -- since they're considered "proprietary" by most manufacturers.  However, a little work with a logic analyzer will likely reveal a whole lot.

The only systems that use existing standard base protocols (or did) are the XPS and (I think) the Jeti ones.  They are/were based on ZigBee.

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