WHO ELSE USES 2.4?

[alan]

Here is a link to a single page explanation of radio control with a diagram showing who or what else uses 2.4Ghz besides microwave ovens,

http://www.gaerpark-mfc.org.uk/rcmodelling-Radio.html

[Peter Royall]

Very interesting, if not alarming, Alan. I'm suprised this hasn't been looked at by all the Clubs 2.4 users. Lets see what we can do?

Oily

[Nutz]

I did have a brief look at this and I was aware of must the stuff on the list but 2.4Ghz is short range and you are highly unlikly to find most of the other stuff that us it (apart from bluetooth on peoples phones or headsets) at the field (maybe a new rule to have wireless devices and bluetooth devices turned off at the field?).

[alan]

Some of the little cameras that we use to transmit from a model to the ground also use 2.4ghz, they might be a worry. I don't think there is really a problem but I thought it was very interesting, the number of devices using 2.4.
I found the info while looking into glitching on 35mhz and found that this can possibly be caused by 2.4ghz microwave communication links; I was getting glitching in one particular place and thought that maybe we have a microwave link beaming across our site! What I could not find was a map of microwave links, maybe maps do not exist since almost anyone could have one. I'm sending this post over a 2.4gig wi-fi!

[Nutz]

Well I think this test concludes things, 73 2.4ghz planes airbourne at once, most are on DSM2 and a few on FAAST

[alan]

I hereby declare that the previous post concludes the thread - but what causes glitching on 35mhz at a single point in space?

[Bravedan]

I hereby declare that the previous post concludes the thread - but what causes glitching on 35mhz at a single point in space?

The congruence of sufficient factors to cause it.

In Norman Park there is an underground pipe run across the field that, depending on the weather, "R" in the month, etc, etc, etc, can regularly cause a minor glitch on 35MHz every time you fly over it if not very high!! We have started an urban myth that it only happens when they are applying leak/flow detecting current.............................

FASST 2.4GHz is totally unaffected.

[alan]

On the advice of Steve I did a proper power on range check with one affected 'plane and got jittery servos at about half the pit length with the aerial down, but could this also cause a sudden glitch followed by apparently normal behaviour? Anyway, good enough reason not to fly it until mended. Bravedan, maybe it's a ww2 uxb under our field!

[Bravedan]

Plane on ground or being held up? Motor running or not?

SOME Tx's almost stop transmitting with the aerial fully down, which give sno accurate guide, so I usually erect one section, and always test with plane held at waist height or more.

UXB?? - let me know how you get on...................

[Bravedan]

Also, did the glitch coincide with the Tx aerial direction, i.e.end on???

[alan]

Power on range check - brushless electric, on the ground restrained by stakes. I have had that thing with aerial completely down so I usually put up one section too. The motor is a type which has extreme "cogging" from the magnets. But the other plane which suffers has a different rx and motor. Seems worse with my "new" tx but the same glitching happened with my old tx but not extreme enough to stop me flying. Is it sunspots?

[PaulC]

One quick thing to think about with Anything 2.4ghz (open/free access band)

The rules governing the use of 2.4ghz are that any system Must be capable of rejecting 'on frequency interference'.

The way most of today's system cope with this is by acting like a computer network, ie digitally...

Each transmitter (RC, Internet Wireless Router, Bluetooth etc) work by wrapping information up in "Packets", think of it like putting a lump of 'information' in a brown paper parcel. they then add an address to it an fire it off into the air.

Any RX that is within range can see the packet and the address and will say 'Is that for me?' if so it will look at the contents and act accordingly, if not it ignores it and continues looking for the next packet. 2.4ghz is sooo fast that 1,000,000's of packets can be flying about and the systems can still work fine and still be quicker than 35mhz.

Our old 35Mhz system didn't use Packets, they transmitted a continuous stream of information with no address that any RX on that channel would blindly follow, this is why 35mhz is channalised and 2.4ghz is not - the channel on 2.4 ghz is the postal address (this is what Binding does when you set up a new 2.4ghz RX/TX, they are agreeing a postal address on which to send and receive packets)

with Radio Control, it was identified that while systems behaving properly would be fine on one frequency, there was a risk if a rouge system fired up and transmitted like a 35mhz set it could kill the frequency so that no packets would get through, this is also the case if a system was high powered or just caused interference on 2.4ghz like a microwave data link - the solution to this was to add an extra layer that allowed for these systems to ether jump frequencies, use split frequencies or rotate through all the frequencies, known to you and me as FASST, DSM, DSM2 etc

35mhz signals actually travel further than 2.4ghz but the digital part of 2.4ghz more than compensates for the lower signal and any interference. this is also why you can fly 70+ models on 40 ish usable frequencies...

Hope this make sense / helps..

Paul

[alan]

That's great Paul, very clear.

[alan]

Earlier in this thread i mentioned glitching but could not solve the problem so took the radio to Avicraft for some free professional help. Ali spent about 40 minutes with me and diagnosed a faulty receiver, confirmed ok with a glitch free flight with another rx. on sunday. I spent about £3.80 with him on a propeller!
So, a big hand please for Avicraft, for looking after their customers.