Model Boat Mayhem

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Author Topic: 2.4 Ghz interference  (Read 9508 times)

Time Bandit

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Re: 2.4 Ghz interference
« Reply #25 on: March 26, 2015, 08:02:19 pm »

It really doesn't matter how complex the transmitted signal is, if it gets swamped by a larger one, the RX regards it as a "lost" signal, and responds accordingly.  In all probability, the more complex the signal, the more liable it is to corruption. Complex handling of the signal allows for a proportion of frames to be lost without any noticeable effect, but exceed that number, and the RX, if so fitted, will go into its alleged failsafe mode.  Failsafe is usually "stick full back", which, for the majority of the market (planes) is "off", which causes them to come down.  For boats, it usually results in full reverse, which is never a good thing.  On old type radios, loss of signal just meant a loss of output to whatever was plugged in, modern, so-called "clever" receivers are quite capable of having a response built in that keeps an output going.  There probably isn't a way to reprogram the RX, only the TX, which doesn't help.
While 2.4GHz is immune to the more conventional forms of interference, being way, way, out of band of the regular sources of interference, with all of the other devices now using the band, low power model control can be swamped and/or crowded out.  Loss of range would be the first symptom, since the signal strength that the receiver gets from its bound TX reduces with range, and there will come a point when the unwanted signal from the interfering source is strong enough to swamp enough information frames.

Absolutely agreed.
But, the thread starter stated that failsave was set correctly during binding, so there is no possibility the ESC goes full throttle just by swamping the signal.
So something is wrong here, or we might consider that we have to rething our common understanding of "logic".
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regards

Tobias

g6swj

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Re: 2.4 Ghz interference
« Reply #26 on: March 26, 2015, 09:48:11 pm »

Probably a red herring! If the fail safe normally results in throttle full back which in a boats case would be full reverse what would happen if the throttle radio channel setup had been setup with servos "reversed"! Would this result in full throttle?


Jonathan
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malcolmfrary

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Re: 2.4 Ghz interference
« Reply #27 on: March 27, 2015, 08:48:29 am »

Probably a red herring! If the fail safe normally results in throttle full back which in a boats case would be full reverse what would happen if the throttle radio channel setup had been setup with servos "reversed"! Would this result in full throttle?


Jonathan
With so many programmable links, red herrings are very possible.  You can tell the TX how to respond, in some cases it might well be possible to tell the RX how to respond to a loss of signal.  Many ESCs have a programmable feature.  All of these are potential pitfalls, especially when you consider the possible permutations. 
Channel reverse plus motor wiring reverse giving a "failsafe full forward"?  Probably, maybe.  I have some cheap ESCs that have an asymmetrical F/R and are designed around Futabas thinking.  To get full forward and a calm reverse I have to do the reversing everything trick.  Other ESCs with relay reversing are bad news if they need to be run "reversed".  The relay puts a large drain on the radio power supply when operated for actual forward.
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