We will be discussing in depth three different unlicensed radio services occupying three distinct radio bands: Multi-Use Radio Service (MURS), Family Radio Service (FRS), and the 900 MHz ISM band. MURS operates in the VHF spectrum, FRS operating in UHF, and ISM devices utilize the 900 MHz spectrum.
Although signals in all three services are line-of-sight, the longer wavelengths are better for open spaces and the shorter wavelengths have greater penetration in buildings and cruise ships. The reason for this is because they can reflect and travel through openings in structures. An MURS radio wave is two meters in length, FRS is 70 cm, and 900 MHz is 33 cm.
In addition to having greater range in suburban and rural areas, the MURS radio service permits external antennas, mobile and base stations. This makes it particularly useful in business applications, as well as farm or ranch management.
However, MURS is a less-desirable choice for communication on a cruise ship because the longer wavelength limits coverage, as well as the service not being authorized for use at any foreign ports.
902-928 MHz handhelds are available for a lower investment, and offer greater performance and flexibility. Although the authorized power level is equal to or less than MURS, the shorter wavelength of the signal allows for greater penetration.