3D Robotics

Some tips on picking frequencies

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I've just added this page of tips on choosing radio frequencies to the manual. Corrections/suggestions?

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Some tips on picking wireless frequencies

Wireless can be something of a black art, and there are a dizzying array of standards and choices. Here are some simple guidelines to help you pick wisely:

  • RC and amateur UAV gear usually operates in these frequency ranges:
  1. 72 MHz (older analog RC gear in the US)
  2. 35 MHz (older analog RC gear in Europe)
  3. 433 MHz (RC and telemetry, in Europe)
  4. 900-915 MHz (video and telemetry, in the US)
  5. 1.3 GHz (video)
  6. 2.4 GHz (digital RC gear, video and telemetry)
  7. 5.8 GHz (video)
  • It is a bad idea to have transmitters and receivers in the same frequency range, so you'll want to choose your equipment to avoid this. Even if they use different frequencies, try to keep transmitters (telemetry, video) and receivers (RC, GPS) as far apart as possible. The only time you should consider having two radios onboard that share the same frequency is if they are digital spread-spectrum radios, such as those in the 2.4 GHz range.
  • In general, the lower the frequency the longer the range because it can go around obstructions better, so 900 MHz video tends to have longer range than 2.4 GHz video. But digital transmission technology can more than compensate for that, so it's not a hard-and-fast rule. For instance, a high-end spread-spectrum 2.4 GHz wireless video setup can outperform a lower-end 900 MHz one.
  • Some frequency ranges are more crowded than others. For instance, indoors and in urban environments 2.4 GHz has to compete with everything from WiFi to Bluetooth to cordless phones. 900 MHz just competes with some cordless phones.
  • 1.3 GHz is quite close to the frequencies the GPS satellites transmit at, and it can degrade your GPS performance. If you are using a 1.3 GHz transmitter, keep it as far from your GPS module as possible.

 

Here are some sample recommended configurations:

RC      Telemetry Video
Configuration 1 (US) 2.4 GHz      915 MHz 5.8 GHz
Configuration 2 (Europe) 2.4 GHz      433 MHz 5.8 GHz

Configuration 3 (US)

Configuration 4 (Europe)

2.4 GHz

2.4 GHz

     915 MHz

     433 MHz

1.3 GHz

1.3 GHz

 

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Comments

  • 3D Robotics

    Hooks, Stephen, Marooned, John Arne: Many thanks for the suggestions. I've incorporated them all above. I'll wait to get a bit more feedback, then copy this over to the ArduCopter and ArduPlane manuals. 

  • Developer

    I generally agree that having a transmitter and receiver on the same frequencies in a UAV is bad.

    But.. 2.4ghz spread spectrum is designed to handle just that. Your average WiFi router has both a transmitter and a receiver and still works. So 2.4ghz telemetry and a 2.4ghz R/C radio should play nice together as long as you separate the antennas (as much as possible to be safe). At the same time it is very important to notice that I am talking about 2.4ghz spread spectrum signals. If you use a powerful 2.4ghz video link, it will not play nice with spread spectrum and will kill the range of 2.4ghz R/C or telemetry transmission for sure.

  • I wonder if for Europe this will be good?

    RC: 2.4GHz

    Telemetry: 433Mhz

    Video: 1.3GHz (as 5.8 seems to have much shorter range)

    And is it a good idea to send telemetry over an audio channel and use only 2 bands instead of three?

  • Chris,

    In the overview you mention 1.3 MHz, I guess you mean 1.3 GHz. Also note that the units should always be MHz or GHz (capital H for Hertz) and always a space between the number and the unit.

    You might want to mention filters, antennas and power which are closely related areas.
  • Also, in EU  868MHz is interesting. see this: http://diydrones.com/profiles/blogs/rc-system-on-868mhz-based-on-op...

  • Moderator
    In EU 72 mhz is no good.. Mil frq.
    We have the 35 mhz band for RC use.
This reply was deleted.