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As with all technology things progress. 2.4Ghz has been around for quite a few years now and in that time the advantages it has over the systems that preceded it have been mostly forgotten, such were the advances it brought and the dominance in use it quickly acquired. What is written below is still as relevant today as the day it was written, but Spektrum 2.4GHz has taken one more evolutionary step now; DSMX. To find out more click on the DSMX logo.......
Spread Spectrum Changed everything, from DSM to DSM2
To start to explain why 2.4GHz Spread Spectrum is such a
quantum leap over the system we have at present, perhaps
it is best to look briefly at just that. If you’ve
been flying for a while you’ll be more than aware of
the problems listed below so skip forward to see how Spektrum
resigns them to history.
At present the majority of flying in the UK uses the 35 MHz
band that is designated solely for airborne radio control.
27 MHz can also be used but is not restricted to air alone,
but in that field is mostly utilised by smaller ready-to-fly
types of planes. For the most part this present technology
serves the modeller well but there has always been several
dogged problems that consistently arise.
The radio systems that have been used up until Spread Spectrum
have no frequency avoidance technology incorporated into their
design. The user has to choose the frequency he wants to fly
on either by the instillation of crystals, or by selecting
a channel on a synthesized system. If someone else is using
that same frequency at the same time within transmitter range,
the resulting interference to each other will take one, or
most likely both models out of the sky.
This problem is dealt with at flying clubs by the use of a
pegboard of some description. Each frequency has a designated
peg. When you want to use the frequency you take the peg and
clip it on your transmitter. That frequency is then yours to
operate on. Downside is that if someone else has the peg for
the frequency your model is on you either have to wait for
it to become free, or change the frequency you are on. Sometimes
too, human error creeps in; someone could leave their transmitter
on after returning the peg, or inadvertently put the wrong
crystals in, there are lots of scenarios that can occur, that
have occurred and will continue to occur.
Finally a problem that has crept in more recently is individuals
buying ready to fly planes and flying them close to flying
fields. Whether they feel they are being more sensible flying
in an area where other models fly or not, all they really do
is run the risk of knocking someone else’s plane out
of the sky.
The bands we use are split into narrow channels and because
of the limited range needed don’t produce a very powerful
signal. Unfortunately commercial users have very much more
powerful transmitters working over larger distances and although
they may use channels in between ours if their equipment slips
off frequency it can cause interference.
Probably more common than most modellers realise, rubbing
metallic parts, radiated interference from ESCs and a host
of other sources generate unwanted RF ‘noise’.
This kind of interference is generated within the range of
present used frequencies and can cause, sometimes unexpectedly,
anything from a glitch to complete loss of control of a model. |
