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Up to now racers have tended to use the 40MHz
band mostly with it being designated almost
exclusively for use with surface vehicles.
27 MHz is of course a general use band so
all types of RC, both surface and air, utilize
it although in general with cars it is mostly
RTR types from the small toys sold everywhere
to the larger more specialized buggies and
trucks found mostly in specialist model shops.
It has to be noted though that there has
been an increase in the use of 40MHZ for
the larger toys in more recent times.
For the most part this present technology has
and does serve the modeler well but there have
always been several dogged problems that consistently
arise. |
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The radio systems that have
been used up until Spread Spectrum have no
frequency avoidance technology incorporated
into their design. The individual has to choose
the frequency they want to use 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 most likely
result in loss of control of both vehicles.
This problem is dealt with at model car 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
you are on you either have to wait for it to
become free, or change the frequency you are
on. During a free practice session at a race
meeting where everyone wants to get on the
track this can mean a long wait. Sometimes
too, human error creeps in; someone could leave
their transmitter on in the pits 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. |
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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. |
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Probably more common than
most modellers realise, rubbing metallic
parts, vibration noise created by IC engines,
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. |
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