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In repeater systems, +5 MHz offset (split) is used, repeater output frequency on the lower frequency. The 5 MHz offset is standard for 450-470 MHz. Many business users operate simplex on either frequency, this is legal if the license specifies mobile operation on the given frequency.
Commercial radios are typically available in the VHF and UHF frequency bands. 30−50 MHz (sometimes called "Low VHF Band" or "Low Band"), 150.8−174 MHz (sometimes called "High VHF Band" or "High Band"), 450−470 MHz "UHF". Many larger populated areas have additional UHF frequencies from 470 to 512 MHz.
Systems in the 450–470 MHz band use a 5 MHz separation with the input on the higher frequency. Example: input is 456.900 MHz; output is 451.900 MHz. Systems in the 806–869 MHz band use a 45 MHz separation with the input on the lower frequency. Example: input is 810.1875 MHz; output is 855.1875 MHz. Military systems are suggested to use no ...
In the 1960s, the UHF 450–470 MHz band was re-allocated to 25 kHz channels. This meant transmitter deviation was reduced to ±5 kHz. This doubled the number of channels available across the entire 450–470 MHz band.
For civil systems in Europe the frequency bands 410–430 MHz, 870–876 MHz / 915–921 MHz, 450–470 MHz, 385–390 MHz / 395–399.9 MHz, have been allocated for TETRA. Then for the emergency services in Europe the frequency bands 380–383 MHz and 390–393 MHz have been allocated.
The 70-centimeter amateur band also provides a wider spectrum than the 2-meter band (in the U.S., this is 30 MHz of spectrum, compared to only 4 MHz on the 2-meter band). [2] This allows for many more channels, accommodating fast scan television , wideband digital modes, and point-to-point linking, which may not be permitted on 2-meter and ...
Frequencies above 30 MHz are referred to as Very High Frequency (VHF) region and those above 300 MHz are called Ultra High Frequency (UHF). The allocated bands for amateurs are many megahertz wide, allowing for high-fidelity audio transmission modes ( FM ) and very fast data transmission modes that are unfeasible for the kilohertz -wide ...
The International Telecommunication Union defines frequency allocation as being of "a given frequency band for the purpose of its use by one or more terrestrial or space radiocommunication services or the radio astronomy service under specified conditions". [2] Frequency allocation is also a special term, used in national frequency ...