Don Fry Posted June 17, 2016 Share Posted June 17, 2016 Peter, please be patient with me, I know little about electronics, but while I can see understand why 'breakthrough" occurs with a mobile next to a radio, I don't see why it should do anything to a microprocessor, after all the same phone has no effect on the I pad I'm inputting this on. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted June 17, 2016 Share Posted June 17, 2016 To repeat as is the fashion on this thread..if you believe an outside source is shooting you down..why are you flying there ? they're your own comments and you're all convinced it's true, so why are you flying there ? John Quote Link to comment Share on other sites More sharing options...
Pete B Posted June 17, 2016 Share Posted June 17, 2016 Off-topic posts deleted - stick to the subject, please.... Pete Edited By Pete B - Moderator on 17/06/2016 13:57:46 Quote Link to comment Share on other sites More sharing options...
Peter Christy Posted June 17, 2016 Share Posted June 17, 2016 Donald, You would be surprised by just how well screened your IPad is! This is not to protect it from outside interference (though it has this side-effect!), but to protect nearby equipment from interference generated BY the IPad! Most computers these days have clock speeds running up into the GHz region, and since the clock functions are square waves, they produce huge amounts of localised RF interference. The American FCC regulations are extremely strict on "spurious emissions" from electronic equipment, and most computer gear is extremely well screened as a consequence. You will be aware of the BMFA advice to not wear a mobile 'phone whilst flying. I actually witnessed a large, scale, turbine helicopter being brought down and destroyed when the pilot's mobile rang whilst he was flying it! We could reproduce the problem on the ground afterwards. Now a mobile phone only puts out a few watts at most. A radar beam or tight beam microwave link *could* have an effective power of hundreds of watts. More than enough to cause either a receiver or decoder to have a severe fit! And before anyone asks, the transmitter in question was not a cheap minority manufacturer, but a very expensive and highly regarded European manufactured one! The BMFA did investigate this back in the 35 MHz days, and showed that wrapping a 35 MHz receiver in cooking foil provided an effective screen against this kind of interference. The same will apply to 2.4 GHz equipment, BUT you will need to be much more careful not to inadvertantly screen out the wanted 2.4 GHz signal. Please range check thoroughly if you try this! -- Pete Quote Link to comment Share on other sites More sharing options...
Phil Green Posted June 17, 2016 Share Posted June 17, 2016 I have an alternate theory - RF blocking tends not to be 'all or nothing', what happens is that the interference causes the noise floor to rise to the point where frames begin to be dropped. Not all frames, one or two with minimal interference, then progressively more as the noise floor rises. Its a gradual degradation of signal quality. We know that Spektrum failsafe occurs after 45 consecutive corrupted or lost frames. Lets say that in an increasingly noisy environment you lose one frame every 45 frames. There will be no failsafe and you're unlikely to notice at all - plenty of good data is getting through. At 3 frames in 45 you might notice some increased latency, you'd still have full control, and no failsafe. At 44 frames lost out of 45 you will have almost 1 second of latency, the servos (or quad equivalent) sticking at the position requested in the last good frame, then suddenly moving to the position commanded in the next good frame one second (ie 44 bad or missing frames) later. But still no failsafe, because at no point has the receiver counted 45 consecutive corrupted or lost frames. In this situation I would expect a model to be uncontrollable. Of course there comes a point where the receiver is unable to consistently resolve sufficient frames or even where no good frames are being received at all, and after 45 corrupted frames (or after the time 45 frames would normally have taken) we get a failsafe. What I'm saying is that it only takes one good frame in 45 to hold the failsafe off. If we're in failsafe, if just one good frame is received, we come out of failsafe immediately - even if the previous 44 and the next 44 are bad. Cheers Phil Edited By Phil Green on 17/06/2016 14:09:43 Quote Link to comment Share on other sites More sharing options...
GARY SHEARS Posted June 17, 2016 Share Posted June 17, 2016 Posted by john stones 1 on 17/06/2016 13:40:50: To repeat as is the fashion on this thread..if you believe an outside source is shooting you down..why are you flying there ? They're your own comments and you're all convinced it's true, so why are you flying there ? John Because this is all new to us who fly there its the first time we have had problems might have been a one off who knows its comments like yours that are not helpful at all Quote Link to comment Share on other sites More sharing options...
Peter Christy Posted June 17, 2016 Share Posted June 17, 2016 Good point, Phil! -- Pete Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted June 17, 2016 Share Posted June 17, 2016 Beg to differ Gary your model is the least important bit in the tale, someone getting hurt outweighs it by a large margin, so other than this thread what action are you taking to ensure it's safe to fly ? John Quote Link to comment Share on other sites More sharing options...
ben goodfellow 1 Posted June 17, 2016 Author Share Posted June 17, 2016 off topic john ,, is one side of this argument ok to post while the other is not? Edited By ben goodfellow 1 on 17/06/2016 14:37:14 Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted June 17, 2016 Share Posted June 17, 2016 Enough.....it ends here. This thread is going nowhere.....topic closed Quote Link to comment Share on other sites More sharing options...
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