dirtybird

My Feedback: (5)

If you are worried get a spectrum analyzer and monitor it. If the noise level gets too high ask that only the fliers turn on their radios.
By spectrum analyzes I mean the $10000 type not the little things you plug into your computer. You can rent them.

Merganser

This all brings back the problems we faced in the late 1950's with control line. No problem with one flyer in the circle, but those crazy combat people were always crossing lines and crashing. Not sure that this adds to the discussion, but out here in Wyoming we seldom get more then 5 or 6 planes in the air at a time. Only worries are the industrial 2.4 controllers running illegal high power limits, skeet shooters and eagles claiming the airspace. jot

rmh

If one actually does this with an analyzer -and there is interference -I would bet it comes from a source other than the radios we use.
As for the radios themselves failing - -my own finding is that all I have seen are user caused -
people yelling" their model is coming unbinded in the air" etc.,
complete lack of understanding how these work or how to use em - and I see more of this now - likely because the proliferation of models ready to fly -right out of the box - these require no understanding of power setup or antenna requirements etc..
The result we are back to a time when people believed in" ghosts and goblins "

JPMacG

My Feedback: (2)

Our radios are code division muliplexed. You will not be able to draw a conclusion from a spectrum analyzer. This is a question for some smart grad student in electrical engineering who is specializing in digital telecommunications. The problem can be modeled with a computer simulation. As I said before, I believe that range will be reduced as the number of users increases. But I am not sure if this will start to be seen at 100 users, 1000 or 10,000.

dirtybird

My Feedback: (5)

Yes you can tell witha spectrum analyzer. Another system looks as noise to your system. Every system on the air contributes to the noise level. If the noise level gets to high your system will not have sufficient processor gain to overcome it and you will be jammed.
I worked in ECCM for awhile and am an EE college grad but I am not very smart..
Exactly what noise level our systems will tolerate is not common knowledge but I expect Andy knows.

JPMacG

My Feedback: (2)

It is possible to communicate with a spread spectrum system below the noise level. This is one of the reasons that spread spectrum was first developed - for covert communications. Noise is not meaningful until it is passed through the digital matched filter that is unique to the code in use.

dirtybird

My Feedback: (5)

Yes the spread spectrum systems can read below the noise level. Thats what I meant by processor gain. But there is a limit to everything.
As the noise level increases withe the number of systems on the air there will be a point where your processor gain wont help.A good spectrum analyzer will give you the noise level in DBM.Digital matched filters dont help when noise hides the code
But we still dont know what the level is that will cause trouble.

JPMacG

My Feedback: (2)

We can use the spectrum analyzer to read dBm, and if we know the gain of the receive antenna connected to the SA and the bandwidth of the SA, we can convert it to power spectral density. But what do we do with this information? At what level does the system start to degrade? I think the only practical way to answer that question is by simulation.