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December 03, 2020, 16:09:55 pm

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Default PPM polarity?

Started by pheasant_plucker, January 10, 2017, 13:12:05 pm

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pheasant_plucker

I have a DJT module fitted to my X12s for my V8FR receivers.
What polarity PPM do I need to set when I bind them?

Gerry
Senior Administrator

The man serving me in the canteen said "Look, You can see the face of Jesus in the Margarine" The Asian guy next to me replied "I can't believe it's not Budda"

Phil_G

January 10, 2017, 14:25:53 pm #1 Last Edit: January 10, 2017, 15:06:33 pm by Phil_G
Either Gerry, Frsky modules are all edge-change triggered so the polarity doesnt matter at all.
On the emulation encoders I used to invert the PPM for JR style modules but theres no point, it makes no difference to a Frsky module.  The PPM pulse width is also non-critical (unlike Spektrum for example where it has to be 400uS)
Cheers
Phil


pheasant_plucker

Thanks Phil, So your saying the receivers aren't bothered which polarity pulse they get?

GErry
Senior Administrator

The man serving me in the canteen said "Look, You can see the face of Jesus in the Margarine" The Asian guy next to me replied "I can't believe it's not Budda"

Phil_G

January 10, 2017, 15:04:42 pm #3 Last Edit: January 10, 2017, 15:09:17 pm by Phil_G
The receivers dont see the PPM at all Gerry. PPM is just a means of conveying stick positions to the RF module input - from then on its all digital, ie packetised data, there is no PPM transmitted,
Thats why CPPM has the 'C',  to look at on a scope its an identical signal, but CPPM is 'combined' from channel data inside the receiver, not passed on from the transmitter in any way as it would be with a 35mhz set.
Cheers
Phil