Modulated continuous wave

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Analog modulation
AM · SSB · QAM · FM · PM · SM
Digital modulation
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Spread spectrum
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See also: Demodulation, modem, line coding, PAM, PWM, PCM

Modulated continuous wave is defined by the Federal Communications Commission in 47 CFR §97.3(c)(4) as "Tone-modulated international Morse code telegraphy emissions having designators with A, C, D, F, G, H or R as the first symbol; 2 as the second symbol; A or B as the third symbol." See Types of radio emissions for a general explanation of these symbols.

Simply put, MCW uses a fixed audio tone to modulate a carrier wave. This is an older method of sending Morse code, with continuous wave being the more common method used today.

Unlike A1A CW transmissions, A2A MCW morse can clearly be heard on a normal AM radio receiver. It was commonly used by many RDF beacons to send a morse station identifier on a regular basis.

MCW is not allowed in the United States on amateur radio frequencies lower than 50.1 MHz, as it is a very inefficient use of radio spectrum.

F2A MCW morse can be heard on a normal FM radio receiver, and it is commonly used by both commercial and amateur repeater stations for identification. Also, F2A is sometimes by other types of stations operating under automatic control, such as a telemetry transmitter or a remote base station.

See also

• Types of radio emissions

References

• "Amateur Radio Service Definitions (47 CFR §97.3)". http://frwebgate.access.gpo.gov/cgi-bin/get-cfr.cgi?TITLE=47&PART=97&SECTION=3&TYPE=TEXT. Retrieved August 3, 2005. 

• "Ham Radio Jargon, Abbreviations and Terminology". http://www.ac6v.com/jargon.htm. Retrieved August 3, 2005.