Radio VHF kalautan
From Wikipedia, the free encyclopedia
Citakan:Globalize
ini pahatu lalis, artinya tidak ada artikel lain yang berpaut ke halaman ini. Bantulah menambah pranala ke artikel ini dari artikel yang berhubungan; atau coba peralatan pencari pranala sebagai saran. |
Radio VHF kalautan dipasang dina sakabéh kapal balayar badag sarta kapal leutik di sagara. Hal ieu ogé dipaké, jeung aturan anu saeutik béda, di walungan sarta situ. Hal ieu dipaké pikeun sagala rupa tujuan, kaasup ngagero layanan kasalametan sarta komunikasi jeung palabuhan, locks, rohang nakodas and marinas, sarta operasi dina kisaran very high frequency (VHF) , antara 156 and 162.025 MHz. Sanajan loba dipaké pikeun nyingkahan tabrakan, pamakéanana pikeun tujuan anu kontroversial sarta pohara nguciwakeun sawatara nagara, kaasup Inggris.[1]
Artikel ieu keur dikeureuyeuh, ditarjamahkeun tina basa Inggris. Bantuanna didagoan pikeun narjamahkeun. |
A marine VHF set is a combined transmitter and receiver and only operates on standard, international frequencies known as channels. Channel 16 (156.8 MHz) is the international calling and distress channel. Channel 9 can also be used in some places as a secondary call and distress channel. Transmission power ranges between 1 and 25 watts, giving a maximum range of up to about 60 nautical miles (111 km) between aerials mounted on tall ships and hills, and 5 nautical miles (9 km; 6 mi) between aerials mounted on small boats at séa level.[1] Frequency modulation (FM) is used, with vertical polarization, méaning that antennas have to be vertical in order to have good reception.
modérn-day marine VHF radios not only offer basic transmit and receive capabilities. Permanently mounted marine VHF radios on séagoing vessels are required to have certification of some level of "Digital Selective Calling" (DSC) capability, to allow a distress signal to be sent with a single button press.
Marine VHF mostly uses "half-duplex" transmission, where communication can only take place in one direction at a time. A transmit button on the set or microphone determines whether it is operating as a transmitter or a receiver. The majority of channels, however, are set aside as "duplex" transmission channels where communication can take place in both directions simultanéously.[1] éach duplex channel has two frequency assignments. Duplex channels can be used to place calls on the public telephone system for a fee via a marine operator. This facility is still available in some aréas, though its use has largely died out. Marine VHF radios can also receive weather radio broadcasts, where they are available.