Chaddt
Posts: 29
Joined: 8/29/2006
From: Carlyle, IL, USA
Status: offline
|
I own/operate a wireless internet business and operate in the ISM bands, including 2.4. In my experience with FCC Part-15 2.4Ghz based equipment is that when there is noise there isn't a whole lot that you can do to battle it besides trying to use narrow/tight beam width antennas to increase your signal to noise by listening to a smaller area. This won't be possble with the RC based 2.4 Ghz equipment. There is a lot of 2.4Ghz noise out there especially once you get off the ground 100+ feet, For example I have a 100' tower in my back yard at the house here that is full of 2.4Ghz equipment if I do a survey from this tower I can see no less that 50-60 2.4Ghz wireless access points in operation from up to 40 miles away covering the entire 2.4Ghz spectrum. I dont see how any of these systems can be immune to 2.4 Ghz noise and if it is FCC certified it has to accept harmfull interference.
Wireless Internet equipment also has unique user ID's but it does nothing to combat noise issues. Its like being in a room with 100's of people and you are trying to carry on a conversation with one person in that room, the louder everyone else talks the louder you have to talk for that person to hear your conversation vs that of the other 100 peopl in that room. The problem is in 2.4Ghz everyone is limited to 1 Watt power so its all about distance from your transmitter to your plane vs the distance of your plane to everything else emitting the noise.
I have both DSSS and FHSS 2.4Ghz equipment in operation providing high speed internet. When it comes to reliablity in a noisy enviroment FHSS will continue to operate long after DSSS throws in the towel "although at reduced bandwidth and increased latency", but FHSS has a lot less available bandwidth that DSSS 2Mb vs 20Mb or more and I am not sure what type of bandwidth is required to fly an RC plane. I would like to get one of the new 2.4Ghz systems but they scare the bajeesus out of me because I know the amount of 2.4Ghz noise that is out there.
With all this being said if someone wants to send my a 2.4 Ghz system I would be glad to test it in the worst possible enviroment, my back yard.
quote:
ORIGINAL: aeajr
Each signal is encoded with a UID which is specific to each person's radios. Even if Spektrum can sense the signal of the 78 other sets while they are on the channels that it is watching, it will reject the signals and only listen for the UID of your radio.
Engineers who are more knowledgable in this matter, am I right?
Now, with all that 2.4 traffic around, is it possible that the reciever might become sluggish because it is filtering all that other stuff? That I don't know, but I doubt it. But I would guess that the Futaba sets are only on those channels for a very short visit. The XPS each grab a channel and hop if they see a lot of noise. So even with all that activity, I would think the noise level would still be within the ability of the receiver to filter effectively.
Engineers who are more knowledgable in this matter, what say you?
Jim, feel free to chime in here.
|
Printable Version
All Forums >> Radios, Batteries, Clubhouse and more >> RC Radios, Transmitters, Receivers, Servos, gyros >> RE: 2.4 GHz - A Broad Market Review 
RE: 2.4 GHz - A Broad Market Review - 
It is strange how my experiences are exactly opposite from yours. I don't know of a single 14mz owner in this area who has had any trouble whatsoever with their equipment. Sure, we read about people having trouble, but that is true of absolutely every radio system on the market. As far as my friends and I can tell, there is nothing to "straighten out" with this radio. 
