The Family Radio Service (FRS) is an improved walkie-talkie radio system
authorized in the United States since 1996. This personal radio service uses
channelized frequencies around 462 and 467 MHz in the ultra high frequency
(UHF) band. It does not suffer the interference effects found on citizens' band
(CB) at 27 MHz, or the 49 MHz band also used by cordless telephones, toys, and
baby monitors. FRS uses frequency modulation (FM) instead of amplitude
modulation (AM). Since the UHF band has different radio propagation
characteristics, short-range use of FRS may be more predictable than the more
powerful license-free radios operating in the HF CB band.
Initially proposed by RadioShack in 1994 for use by families, FRS has
also seen significant adoption by business interests, as an unlicensed,
low-cost alternative to the business band. New rules issued by the FCC in May
2017 clarify and simplify the overlap between FRS and GMRS radio services.
Worldwide, a number of similar personal radio services exist; these share
the characteristics of low power, operation in the UHF (or upper VHF) band
using FM, and simplified or no end-user licenses. Exact frequency allocations
differ, so equipment legal to operate in one country may cause unacceptable
interference in another. None of these radios working with frequencies in the
FRS frequency band are legal to operate anywhere in Europe.
https://www.409shop.com.hk/shop.php
沒有留言:
發佈留言