From radio control systems of the models were first built more than half a century, technology has been "narrow band". Narrowband refers to the amount of space that the signal into the frequency spectrum available. Today FM / PCM radio control systems operate in a small strip of space frequencies relatively low (27, 35, 36, 40, 41 or 72Mhz).
In terms of radio which means that almost any other sign of narrow-band frequency being used will lead to interference (glitches or lock-out). Clearly this is not the best situation for the control of a potentially costly and sometimes dangerous radio-controlled model, but be careful channel management, which has served well for decades RC Hobby.
Manufacturers 2.4 GHz spread spectrum (SS) radio systems are saying that you never have to worry about being shot down by other flyers and that all systems can get 2.4 GHz along the line, although apparently with the same frequencies. The first and most common type of systems is what we call 2.4GHz Direct Sequence Spread Spectrum (DSSS). This implies that the transmitter and receiver remain within a fixed part of the 2.4GHz spectrum. The second type is called Frequency Hopping Spread Spectrum (FHSS) and consists of having the transmitter and receiver constantly changes its operating frequency within permitted limits of the 2.4GHz band.
Spectrum offers some very clever ways to reduce the effects of radio interference and allow a lot of games different to operate simultaneously without the need for a frequency pin. With the way these systems spread their signals across the thin strip 2.4 GHz and thanks to the way some of them jumping in order to remain a moving target, you need a very strong signal interference to lapse. system DSSS can be eliminated if the strength of an interfering signal in that channel is strong enough.
reputable manufacturers realize that their systems can be in control of large, expensive models and potentially dangerous so they try to allow possible contingencies. Futaba uses frequency hopping constant JR / Spektrum use a backup channel (a tactic known as redundancy). Another important aspect of the system of 2.4 GHz spread spectrum radio control is something called diversity. Diversity is necessary because the radio signals to 2.4 GHz behave very differently than we're used to seeing in frequencies low as 72MHz.
Whereas narrowband frequencies will age to the right through objects such as houses, trees, fences, and model airplanes, 2.4 GHz behaves much like light being absorbed or reflected by many parts of the environment. This absorption and reflection of the results 2.4 GHz signal at times when the receiver antenna can be protected by parts of the model, or may be subject to the kind of ghost that used to be seen old television set when the signal was reflected in the trees or buildings (called multipath). The effects of protection and / or multiple means it is very possible that the receiver can not hear the station clearly enough to extract the data being sent. The simplest (and best) solution to this problem is use more than one antenna and / or more than one receiver in your model. When mounting the antennas or receivers in different locations (even if only an inch or two away), a can take over if the other is unable to get a clear signal.
The JR / Spectrum system allows multiple receivers, as four or more and some of these receivers have multiple antennas. This is undoubtedly the diversity of final installation. In very large models can be absolutely sure that there is no possibility of shielding multi-channeling or simply increasing the number and distribution of receptors in the plane.
Futaba FASST system uses two antennas mounted on a receiver. In theory, this is not as good as that of JR / Spektrum option but in practice seems to work perfectly adequate.
It is true that you can not be demolished control by another 2.4 GHz radio system, but still there is always the possibility that other forms of interference can make you lose control of your model. 2.4 The band GHz is used by a wide range of other electronic equipment for wireless Internet for microwave ovens. There is no guarantee that one of these other devices that do not interfere RC as a whole.
spread spectrum radio with working sets in a way very similar to PCM in the form of responding to the strong interference. If you have poor lucky enough to experience interference so strong that the link between sender and receiver is lost, the receiver will enter "pending / lockout" mode and then go to Safe mode (if set). The cause of this lockout / failsafe can be almost anything, including, but not only limited to the interference. In fact, in the case of spread spectrum systems, experience has shown that the locks are much more likely to be caused by inappropriate cell model or improper installation.
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