Help, please. Radio frequencies...

[noah]

I have a question about frequencies.  The rules of this science contest I'm doing says:

 "only commercial radio control equipment intended for unlicensed remote control vehicle operation may be used. For example, transmitters whose operational frequencies are in the 75 MHz band, 27 MHz band, 49 MHz band or the 2.4 GHz band. Robots may not use equipment that requires a license to operate."

I have found some remote controls that have a 72 MHz frequency. Would this work or would it be against the rules?  Can I alter the frequency of a transmitter?

Thanks for all your help!
Noah

[airman00]

It would be fine(they won't hunt you down) , but if I recall correctly 72 mhz is used for R/C aircraft, so dont control your robot near an R/C airfield

[noah]

              thanks!

[Razor Concepts]

Technically it's illegal to use 72mhz on anything that operates on the ground, but it's not like anyones gonna know 

[paulstreats]

I think 72mhz is reserved for radio controlled helicopters and aeroplanes so just make sure none are in the vicinity when you use it

[TrickyNekro]

Get a remote with decryption....
They are more expensive but less prone to cause a disaster....
Also, note that...
It's basically legal to transmit in any frequency as soon as the power of your transmitter do not extent the regulations....
In R/C these limits are far far extended....

[Razor Concepts]

2.4ghz is the way to go, you can use it land and air, and there is basically no interference.

[householdutensils]

Also, note that...
It's basically legal to transmit in any frequency as soon as the power of your transmitter do not extent the regulations....

That's not really true. A good chunk of the radio spectrum is heavily policed, transmitters of any kind need to be licensed to operate on regulated bands.

Companies like Iridium pay millions of dollars for their spectrum licensing packages.

[izaktj]

Can I alter the frequency of a transmitter?

Yeah, just change the crystals on Rx and Tx.

[TrickyNekro]

As far as the transmittion doesn't extend from your property it's all right... That's the limits I mean...
If you haven't noticed NOKIA has a cellphone with a about 0.5m fm transmitter...
Was so nice hearing your music in a cab after clubbing, and the driver just to wonder what hit him!!!!
And if you are good with electronics you can basically extend it's range dramatically....
 up to 3 - 4 meter running from the Li-ion battery of the cellphone...

Yes, I'm an original prankster!!! Period!!!

And thing is that I don't live in a country that doesn't suffer from electromagnetic wave pollution...
This means.... that even if I transmit in illegal frequencies, I must cause a problem many times so that I'm reported
then police tries to find who and you are simply noted some times before paying fines....
Unfortunately the bad thing about where I live is that I have a military Radar in the view field of my balcony...
So..... This makes it pretty easy to find me....
But who cares.... You can transmit your VHF for your plane..... and never get caught....

[householdutensils]

In any country with an established spectrum management policy, even on your own property it would be illegal to use regulated bands. Regardless of the range of the transmitter. Though the spectrum is pretty broad, we're talking talk back to sat comms, so obviously you're not gonna get in trouble for using little FM Transmitter, but if you've built a base station for communicating with satellites, expect to get a big fine xD

Your totally right though, it's pretty difficult to get caught unless your using some pretty hefty kit that can cause interference.

[cooldog]

all the fequenceys

http://www.societyofrobots.com/remote_control_robot.shtml#RFrefchart

[noah]

I think I "get it" about the different frequencies being used for different types of robots--flying, surface etc.  And I am fairly certain that the contest will require that I operate at a surface frequency--i.e. the 75 MHz.  I am waiting to hear from the officials (by the way, has anyone ever participated in this thing called the Science Olympiad??? It's pretty cool).

How easy is it to change the frequency crystal to switch a 72 to a 75?  From my research it looks as simple as popping one out and switching it with the desired one.  Am I right?  The reason I ask is that I've found some reasonable priced 72 transmitters on e-bay and Tower Hobbies.  I'd appreciate any feedback and again, I am very grateful for all you've shared over the past couple days.  You rock!

                                                                     Noah

[cooldog]

From my research it looks as simple as popping one out and switching it with the desired one.  Am I right? 

yes it is

[Razor Concepts]

No you can't switch crystals to run on 72 or 75. You can switch between the specific values (ie, 72.012 to 72.022 or something like that), but you cannot interchange 72 and 75 crystals.

[Admin]

The judges will probably check the frequency written on your crystal in your transmitter.