FREQUENCY MODULATION
radio modulation techique where information (usally voice or music) is added to the signal and changed by varying the freqeuncy of the transmitter. FM is the most commonly used modulation for radio signals techneque above 30 MHz.
the term "FM" is also used to refer to the broadcast band from 88.1 to 107.9 MHz, using that same modulation mode.
radio modulation techique where information (usally voice or music) is added to the signal and changed by varying the freqeuncy of the transmitter. FM is the most commonly used modulation for radio signals techneque above 30 MHz.
the term "FM" is also used to refer to the broadcast band from 88.1 to 107.9 MHz, using that same modulation mode.
FM signals have less static because changes in frequency do not pick up interferance that AM-modulated signals do.
by IrishRepublicanArmy October 17, 2003
radio term
ha ha (laughter)
"hi hi" is the Morse equivalent of a laugh as in Morse it sounds like someone chuckling ("hehhehhehheh hehheh"). That is ditditditdit dit dit --- or dot dot dot dot dot dot. You really have to listen to it sent in Morse to appreciate its laugh like sound. It is most commonly used in CW (Morse Code), but has carried over to voice as well. Many CW expressions have carried over to voice -- such as 73 (Best Regards) and 88 (love and Kisses), etc. The origin probably dates back before radio to the telegraph days. And since Hams used Morse long before voice became practical-- the sound of the Morse characters HI HI was used to resemble a laugh sound. In some sense it is equivalent of a smiley. It's onomatopoeic -- that is the naming of a thing or action by a vocal imitation of the sound associated with it (as buzz, hiss) The definitive answer might be found in the "Dodge's The Telegraph Instructor Manual" circa 1850 to 1900. However, I have never been able to find a copy of this document. Wish I could as it would help to see the transitions from telegraph to radio usage.
ha ha (laughter)
"hi hi" is the Morse equivalent of a laugh as in Morse it sounds like someone chuckling ("hehhehhehheh hehheh"). That is ditditditdit dit dit --- or dot dot dot dot dot dot. You really have to listen to it sent in Morse to appreciate its laugh like sound. It is most commonly used in CW (Morse Code), but has carried over to voice as well. Many CW expressions have carried over to voice -- such as 73 (Best Regards) and 88 (love and Kisses), etc. The origin probably dates back before radio to the telegraph days. And since Hams used Morse long before voice became practical-- the sound of the Morse characters HI HI was used to resemble a laugh sound. In some sense it is equivalent of a smiley. It's onomatopoeic -- that is the naming of a thing or action by a vocal imitation of the sound associated with it (as buzz, hiss) The definitive answer might be found in the "Dodge's The Telegraph Instructor Manual" circa 1850 to 1900. However, I have never been able to find a copy of this document. Wish I could as it would help to see the transitions from telegraph to radio usage.
by IrishRepublicanArmy January 01, 2004
by IrishRepublicanArmy December 21, 2003
by IrishRepublicanArmy December 20, 2003
Dual Tone Multiple Frequency. Pressing a button on the keypad of a touch-tone phone generates a pair of tones of specified frequency and duration. The network or the equipment at the other end of the connection (such as a remote control for a phone answering machine, or a telephone interconnect system) detects and interprets these tones. In analog networks, audible tones generated by the network provide the call progress indications to the user. Different tones allow the human ear to interpret the progress of the call. On digital networks (such as PBX or ISDN), the network may send indication messages to the phone to indicate the status of the call, and the phone may generate most tones locally, driven by those messages.
by IRISHREPUBLICANARMY January 10, 2004
by IrishRepublicanArmy January 01, 2004
High Frequency
radio communication services from 1.8 to 29.7 MHz, used for long-range communications, the only band used for worldwide communcations other then mircowave and UHF satellite services
radio communication services from 1.8 to 29.7 MHz, used for long-range communications, the only band used for worldwide communcations other then mircowave and UHF satellite services
"Johnson, get Washingtion on the HF"
by IrishRepublicanArmy October 12, 2003