The only remote control units I have used before was those little cheap 27Mhz puny range cheap units. I would like to build some sort of RC unit, which has a range up to 1km line of sight.
I have a general license. How can I get started with remote control using Amateur frequencies, and what bands allocate remote control?
This might be better as a comment than an answer (Mods feels free...) but...
Given your callsign is from the USA, your terms are different from mine in the UK, but please check the terms of your licence... I could be wrong but I suggest that what you are proposing using ham bands for is outside the privileges contained therein.
Furthermore, remote control implies operating on a fixed frequency - therefore if used on ham bands, you are at risk of causing interference (QRM) of other users.
A remote control is just a radio transmitter (maybe even a receiver if you expect to get data back from whatever you're controlling). To get started, you'll need to learn how to build a transmitter/transceiver that operates at the appropriate frequency.
That's probably the easy part. schematics for VHF/UHF transmitters shouldn't be too hard to find.
The harder part would probably be adding the controls and making them tell the transmitter to send the appropriate modulated signals out, which would require some kind of microcontroller to read the status of the controls, and then appropriately key the transmitter in response. That's probably your next step.
Then you'll need a receiver on the device you're controlling. Receivers are generally fairly easy objects to build, but now you've got to make it control things on your device in response to the signals it receives. More microcontroller stuff.
I would strongly consider a Zigbee or 802.11 based approach. Both have cheap hardware available, are relatively easy to integrate with electronics (via a microcontroller such as an arduino), and operate on frequencies which you have extra privileges with your ham license.
Depending on what you are wanting to control, it would be fairly easy to control via software on a PC or tablet, you could even connect a game controller. If you want something that doesn't require a PC on the transmitter side, there are a lot of options to connect a USB joystick directly to a Arduino type micro controller.
I would favor a digital approach like I described above, but I'm a software guy. If you wanted something more old-school and analog, you could implement a protocol like the RC transmitters use. Essentially you send digital pulses of varying lengths, and the length of each pulse determines the value of the control. More info on that can be found online, for instance this site: http://rcarduino.blogspot.com/2012/11/how-to-read-rc-receiver-ppm-stream.html
I recommend you don't reinvent the wheel. There are two amateur radio bands in the US the FCC sets aside for line-of-sight remote control for planes and surface craft (boats, cars, etc). The RC community has determined standard frequencies and uses the same modulation and protocols as on other license free bands, so as long as you follow their guidelines you can get equipment off-the-shelf that allows you to use your general license to access RC frequencies that are uncluttered by other unlicensed users.
RC frequencies are located at 27MHz, 50MHz, 72MHz, and 75MHz. License free users can only use frequencies in the 27MHz and 72MHz bands. The RC community has already created a channel list for all the available frequencies:
http://rcsource.hobbypeople.net/faqs/freqlist.htm
You can find transmitters and receivers that work across that range from RC retailers, though it's unlikely that local stores will stock Amateur Radio band RC equipment. They can be special ordered, or found from online retailers.
You can often find suppliers by searching for keywords such as "RC", "50MHz", "75MHz", "transmitter", and "receiver".
Once you have a working system at your desired frequency, then you might want to improve on it. Starting with a good system makes the next step easier, rather than starting from scratch.
Edit in response to a comment I am unable to reply to.
Given the use of consumer drones for remote-controlled air and watercraft as very effective weapons of war, restrictions on what can be used for radio control of all kinds of vehicles are under tighter scrutiny. Be sure to comply with local laws,
As of 9 July 2024, in the UK, you need a license to fly any RC vehicle with a camera or heavier than 250 grams. The USA has a similar law, with the addition of aircraft carrying an GPS that broadcasts its location, altitude, speed, and heading. There are no links, as this information will change over time.
I have held an Extra ticket for 25 years. In the UK, 433 & 868 MHz are available for LoRa. In the USA, only 915 MHz can be used for LoRa without a license; 433 MHz falls in a multiple-use band in the USA, with Amature radio operators among the users. The LoRa specs list the frequencies worldwide.
Most countries issue special or experimental radio licenses for uses that don't fall under the licensing rules. Those require a formal request to the government licensing bureau with a full explanation of the project and why you need an exception. In the case of R/C aircraft, it would probably need the OK from the Aircraft authority and the military. ---- end of edit
I am replying to an 11-year-old question that did not get a good answer. LoRa and SDR, standing alone or combined with Ham Radio transmitters and receivers, offer new options.
Ham radio has a rich history of being utilized for radio control, a practice that has been in place for at least the past 70 years, as far back as my own awareness of Ham Radio and model airplanes. A Technician license is all that's required to operate on the Amateur bands at 50 MHz and above, where radio control is permitted. It's worth noting that two meters are generally not used for remote control, as there are other, less commonly used bands available.
If I had a loss of signal problem with a line-of-sight radio-controlled aircraft, I would try a single Borad ARM microcontroller with onboard Long Range WiFi (LoRa). I would try building horizontally polarized antennas on the wings with modest gain at 90 degrees to one another. If there is a problem with signal loss due to trees, buildings, or hills, a 1-watt, not 5-watt, 50 Mhz transmitter will handle those problems better than higher frequencies at the cost of interference from skip signal bounced off the ionosphere.
An SDR receiver connected to the microcontroller board with LoRa should work as the receiver and sort out the control functions on the aircraft.
73 W5RED
