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LaurieB

Max number of concurrent 2.4 ghz radios

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A question for the techies out there:-


From a technical pov is there is a maximum to the number of 2.4GHX radios that can be used concurrently before there is a risk of interference between sets. My Google research suggests the answer is no but just want to be sure


Cheers


LaurieB

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In practical terms of RC Yachting, Cars and Aeroplanes the direct answer is NO. The limitation is more related to Density of the craft themselves.


Each Transmitter sends data packets just as any network that you are accustomed to working with in the time domain i.e. shout when there is a gap and receivers listening for their name to be called. RC transmitters do not listen for a gap they just shout all the time.


But with the 2.4 GHz and 4 GHz systems there is an added dimension of Carrier Bandwidth. So now you have a 2 dimensional arrangement where you listen for your name across the spectrum.


The data packet of a RC system is very small, 10 to 20 words or so.

Name, Chanel 1, Chanel 2 …..Chanel n.


Competing companies use, implement, differing approaches to using, Modulating Carrier. i.e. Defining the Mark and Space in the word.

But they most do NOT develop them, they are defined in the Chip Set, the little black things with legs. they buy mostly from China.

The each Chanel is only updated, refreshed, every 3ms or so. So there is lots of time to get a new packet, update without losing any control integrity.


It is like listening for your name to be called in a crowded room while everybody is talking.


Some RC system are not Band Friendly and shout a lot , shout loudly and shout widely effectively using up the two domains time and width badly.

Adding to this is that there are more than RC systems using this Band , Bluetooth, and dozens of other applications. Adding to this are the greedy RC systems sending data back to the transmitter, Batter voltage, and 10 other packet of nebulous data.


Very uncool.


It is very easy to jam up the 2.4 GHz band such that no data transfer wold be possible; regrettably this equipment is easily and cheaply available.


Ok that is the simple explanation.


Now I have a question – When and Who implements the first fully Radio Controlled craft and where did he demonstrate it ? Call may be charged at £1.00 entries close 1March.

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Thanks for replies chaps, thought No was the answer but good to have the confirmation.


To answer David's question, I'm going to go for :-


When - 1898

Who - Nikola Tesla

Where - Madison Square Gardens

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Laurie,

You have it correct

Well ahead of Futaba !


I will bet that Edison was well peeved particularly since Tesla had been employed by Edison a few year before.


His success was to a great degree due to Lodge NOT patenting his Diode which opened the development of Radio as we know it. Lodge did this deliberately as he firmly believed the delivery should benefit ALL mankind.


Marconi patented the application of Radio not radio. But Tesla was working on Transatlantic communication well be for that as contract to .....WHO ?


But his interest was in transmission of Energy not the Stock exchange DATA that ..... was disparate to get before anyone else




Dave in the Istanbul snow. I will bet it will be the same in UK when I land tonight


Dave

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