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Originally posted by Justin Stiltner First and IFI would prefer that we use whatever is appropriate for our uses, IE if the edu R/c was in an aircraft, use aircraft band, however they wont make a rule against use of it.. because the edu r/c isnt used in competition, and we wont be using the hobby r/c system in actual competition or with the real robots.
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Yes, using the aircraft band IS illegal, period. Regardless of a FIRST ruling, DON'T use the aircraft band for your robot under ANY circumstances.
From a practical point of view, remember that in some areas schools often have the
only clear field, so
many R/C airplane enthusiasts use local school yards after school and on weekends for their flying. If you fire up your edubot on an aircraft band while someone is flying in your school's field nearby, you'll probably crash their plane. Believe me, they'll be pissed off, and your team could even be liable for the damages to a multi-hundred dollar R/C airplane because you were illegally on their frequency.
Considering the exponential growth in the number of schools involved in FIRST these days, the constant elimination of other clear fields in communities from population growth housing/building construction, and the fact that our "hot" time includes almost
two months of contiguous weekends, conflict is a non-trivial possibility that will only increase with time.
Therefore, use ONLY ground frequencies. If you crash someone's car, you were both on the band legally (and R/C car are
expected to take crashes!
)...
BTW, regardless of ground frequency, R/C car controls are often only two channel. Given a four or more channel radio if you skip the first two servo channels for your drivetrain you'll protect yourself from most R/C Cars that
happen to be on the same frequency (though your grippers may be "jumpy", so watch out). Even if they have more channels, R/C cars normally use the first two servo channels for speed and steering and the rest for switches, which simply turns your motors on to a set value instead of making them behave wildly as they run their car.
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BTW, Another advantage of FM radios is that they tend to "lock" onto the strongest nearby transmitter. Since all are roughly equal in power (with full batteries), that means a given receiver normally listens to the
closest transmitter of that frequency, which
should be yours.
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Originally posted by Joe JohnsonFrom my discussions with my local hobby shop folks, it is my understanding that
#1 Any of the aircraft radios/controllers can be purchased in ground frequencies (typically local shops will not stock them but you can get them in 2-4 weeks)
#2 Most manufacturers have programs where (for a fee) you can get aircraft radios retuned to ground frequencies.
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#1: True. The problem is that most ground freq radio sales are for cars, which are typically only 2-4 channel and use the "knob/trigger" controls, so that's what they stock. Most joystick >=4 chan radios stocked locally are for planes and choppers, all on the wrong band(s). Therefore, you'll probably have to order it. Online ordering is normally the fastest and cheapest, but if you work through your hobby store, you get local sales/service assistance (and maybe a new team sponsor!!!).
#2: Depends
highly on the brand,
and the model. High end models/brands are often worth the changeover, as they normally have modular transmitter "bricks" which can be swapped out easily in minutes. OTOH, Cheapie rigs normally aren't worth the effort and expense for the entire guts are on one PCB. You'll either basically have to replace the entire board inside to change the transmitter's band, or incur a tech's bench time to change components and realign the radio. Either of these tasks can easily cause the retrofit to exceed the price of a new transmitter.
- Keith