KPH has always been mainly a Morse code station.
International Morse code is used on the air, but American Morse code was once used on the telegraph lines ("land lines"), so operators at the station had to learn both varieties until the landline telegraph was replaced by the
teleprinter. In the beginning, all traffic was sent by Morse code ("CW") using hand-operated Morse keys. Devices were introduced to allow messages to be typed or "punched" onto a paper tape so that they could be sent automatically at any time. Station IDs and other repeated announcements pre-recorded by this method are called "wheels". In the 1930s, landline teleprinter operation was adapted for radio use (radioteletype or "
RTTY") which allowed for faster, more efficient messaging. This did not replace Morse code entirely, because many vessels had no teleprinter equipment and because Morse was the most reliable transmission mode available: When faced with bad atmospheric conditions and weak signals, dits and dahs are easier to pick up than teleprinter or the human voice, and all the coding and decoding are done in the brain. Over the years radioteletype was improved and computerized, giving rise to new digital transmission modes such as
Clover and
PACTOR. Satellite communications became a technically and commercially viable alternative to terrestrial radio links. Ship radio equipment became more advanced and automated, requiring fewer radio officers – or none. By the 1990s few ship stations were equipped for Morse code or had any use for it, so coast stations re-allocated their Morse frequencies to other uses. Some stations disappeared from the airwaves altogether, as did KPH after being acquired by
Globe Wireless in 1997. Its Morse code traffic was then diverted to other stations such as KFS in
Half Moon Bay, California, another Globe Wireless station. KFS continued to handle Morse code traffic until 13 July 1999
Universal time (actually July 12 in the
Pacific time zone) when it made its last official Morse transmission, ceremonially marking the end of commercial Morse code use in America (as distinct from
amateur radio Morse code use, which continues). This anniversary is commemorated on the air every July as the "Night of Nights" by KPH and other coast radio stations, along with radio amateurs who participate on their own frequencies. ==Revenue service and preservation==