EEVblog Electronics Community Forum
Electronics => RF, Microwave, Ham Radio => Topic started by: rymste on January 31, 2017, 12:23:36 am
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I have my Technicians license and a few cheap 2 meter and 70 cm radios and would like to use them to control a Rc aircraft. I have hacked the headphone and microphone cable so i can control the PTT, speaker out, and microphone in. My plan is to use an arduino to create tones to be played into the radio and the other radio to receive the tones and have the other arduino decode them and control the servos. Are there any suggestions on how i should do this differently or if it is even possible. Thank you.
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For analog based control I'd look into PPM/PWM as has been used in traditional RC for years. Also consider how you plan to identify, and in most cases one way transmissions in ham radio are not allowed. I used the 6 meter band for years to control my RC cars - there is a provision to use it with low power which removes the requirement to identify with your callsign.
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It's been a while since I got my license and I haven't been real active in ham stuff lately but as I recall, what you are proposing to do is not legal. What I primarily use mine for is running a video transmitter onboard the aircraft for FPV flight.
For the control, good reliable RC equipment is so cheap these days it makes little sense to cobble something together, especially when a fault could seriously injure someone or damage property. If you're on a tight budget there are loads of obsolete analog FM RC systems available for peanuts since almost everyone has switched over to 2.4GHz spread spectrum.
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I thought about this when I first got licensed as well. Never did anything with it. The power levels are limited as you can see from the rules below.
FCC rule:
ยง97.215 Telecommand of model craft.
An amateur station transmitting signals to control a model craft may be operated as follows:
(a) The station identification procedure is not required for transmissions directed only to the model craft, provided that a label indicating the station
call sign and the station licensee's name and address is affixed to the station transmitter.
(b) The control signals are not considered codes or ciphers intended to obscure the meaning of the communication.
(c) The transmitter power must not exceed 1 W.
[54 FR 25857, June 20, 1989, as amended at 56 FR 56171, Nov. 1, 1991]
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How does the 'codes or ciphers' part work? If somebody implemented their own spread spectrum with a pseudorandom sequence, is that allowed because the intention is not to obscure the information?
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I am not sure how it'll work but if you have any suggestions that would be helpful. Thank you.
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I think you just need to publish your proprietary code and follow the rest of the rules and you should be good.