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What are these frequencies used for within the drone technology, and why these values?

  • 35 MHz
  • 433 MHz
  • 868 MHz
  • 2.4 GHz
  • 5.8 GHz
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Spectrum licensing

There are only a limited number of frequencies in unlicensed bands which can be used for radio control, and different countries have different licensed bands for different uses.

For instance:

  • 35MHz is available for RC use in many countries in Europe, but other countries use a whole variety of other frequencies below 100MHz.

  • 433MHz is in the ISM Band in Region 1

    • That's the "industrial, scientific and medical radio bands" for use in "Europe, Africa, the Middle East west of the Persian Gulf including Iraq, the former Soviet Union and Mongolia".
  • 868MHz is allowed for "Non-Specific Short Range Devices in Europe" within certain limits.

  • Finally, both 2.4GHz and 5.8GHz are ISM Bands with worldwide availability.

I found much of this information in the ISM-Band and Short Range Device Regulatory Compliance Overview document from Texas Instruments.

Frequency characteristics

In terms of actual use, different frequencies have different advantages and disadvantages. So in general:

  • Lower frequencies require a larger antenna and generally have a lower data rate, but require less power and have fewer line of sight issues.

  • Higher frequencies have more bandwidth available, so you can get more/wider channels and a higher data rate (see the Shannon Hartley theorem) and you can can use smaller antenna, but line of sight starts to become a major issue, and you need more power for the same range.

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    $\begingroup$ Just as a follow-on comment to this answer, higher frequency transcievers allow for higher data rates. $\endgroup$ – Chuck Jun 16 '15 at 22:26
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    $\begingroup$ That's worth an answer on it's own @Chuck, though technically, higher speeds are enabled by more/wider bandwidth channels rather than the frequency itself - you have many more 5MHz bands at 5.8GHz than at 100MHz *8') See the Shannon Hartley theorem. $\endgroup$ – Mark Booth Jun 17 '15 at 19:27

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