Two Way Radio Technology
History | Uses | Types | Two Way Radio Frequencies | Push To Talk | Make Your Own

Two-Way Radio Frequencies

  • Operate on many different frequencies, which often differ in different countries.
  • Usually radio frequencies are preselected so that the user does not have to tune into a certain frequency, but can easily choose a frequency by pushbutton.
  • In the US there is a block of 22 channels assigned to the General Mobile Radio Service and Family Radio Service.
  • The selection of a frequency for a two-way radio system is affected by:
    • Government licensing and regulations
    • Local congestion or availability of frequencies
    • Terrain, since radio signals travel differently in forests and urban areas
    • The presence of noise, interference, or intermodulation
    • Sky wave interference below 50-60 MHz and troposphere bending at VHF
    • In the US, some frequencies require approval of a frequency coordination committee.
  • Each country allocates radio frequencies to different two way services. In the US some examples are: Citizens Band, FRS, GMRS, MURS
  • Channel numbers are used as shorthand notation for a frequency in two way radios.
  • Amateur radio operators nearly always use frequencies rather than channel numbers since there is no regulatory or operating requirement for fixed channels.