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On the United States Radio frequency allocation chart, the term "fixed" radio comes up a lot. What does that mean? Who is allowed to used "fixed"?

skyler
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Generally we distinguish two types of stations:

  • Mobile, when the device is portable
  • Fixed, when the device stays on one location

See Amateur Radio Stations for more information:

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(left: fixed; right: mobile)

Community
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Fixed wireless is normally used as a term for radio communications between fixed locations such as buildings that don't move as opposed to mobile communications. One reason the allocations are treated differently is that for a fixed location it's often possible to allocate the same frequency to different regions.

For example for a given installation it may be determined for a specific frequency / power range that interference is only likely within a 10km radius, giving the possibility that the same frequency may be used hundreds of times by different users within a country as long as they are geographically far enough apart. That assumption of course can't be made for mobile communications systems that move around.

License costs are normally a combination of power and bandwidth and how far the signals are likely to emanate and also population density. I can only only speak from an Australian perspective but I believe here anyone is allowed to use fixed frequencies if you pay the license fee and it is approved. That may range from hundreds of dollars per year for a narrowband low-power license (for example courier voice communications over a limited area) and into millions for the sort of allocation you'd need for TV broadcasting over a large area.

PeterJ
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http://www.ntia.doc.gov/files/ntia/publications/2003-allochrt.pdf ? (That is one ugly chart.)

Opposite of "mobile": the transmitter is at a fixed location. Why are there different rules for fixed and mobile? Because an interference problem caused by a mobile transmitter is a lot harder to track down.

pjc50
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  • It's better then Europe's!!! So who gets privileges to use fixed? – skyler May 30 '13 at 12:54
  • Exact regulation depends on the band, but there's a set of bands allocated for amateur ("ham") radio, and a training and certification process to be allowed to broadcast on them. Amateur radio is very much a community of its own. – pjc50 May 30 '13 at 13:09