Modulated continuous wave (MCW) is Morse code telegraphy, transmitted using an audio tone to modulate a

carrier wave In telecommunications, a carrier wave, carrier signal, or just carrier, is a waveform (usually sinusoidal) that is modulated (modified) with an information-bearing signal for the purpose of conveying information. This carrier wave usually has a ...

. The

Federal Communications Commission The Federal Communications Commission (FCC) is an independent agency of the United States federal government that regulates communications by radio, television, wire, satellite, and cable across the United States. The FCC maintains jurisdiction ...

defines modulated continuous wave 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 The International Telecommunication Union uses an internationally agreed system for classifying radio frequency signals. Each type of radio emission is classified according to its bandwidth, method of modulation, nature of the modulating signal, ...

for a general explanation of these symbols. Types of Morse code radio transmissions (CW and MCW) discussed in this article include: * A1A and A2A — Double-sideband

amplitude modulation Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to ...

(AM); One channel containing digital information, no subcarrier (A1A) or using a subcarrier (A2A); Aural telegraphy (intended to be decoded by ear) * F2A —

Frequency modulation Frequency modulation (FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave. The technology is used in telecommunications, radio broadcasting, signal processing, and Run-length limited#FM: .280. ...

(FM); One channel containing digital information, using a subcarrier; Aural telegraphy * J2A and J2B —

Single-sideband In radio communications, single-sideband modulation (SSB) or single-sideband suppressed-carrier modulation (SSB-SC) is a type of modulation used to transmit information, such as an audio signal, by radio waves. A refinement of amplitude m ...

with suppressed carrier; One channel containing digital information, using a subcarrier; Aural telegraphy (J2A) or Electronic telegraphy (intended to be decoded by machine) (J2B) Unlike A1A CW transmissions, A2A MCW will produce an audible audio tone from an AM radio receiver that is not equipped with a beat oscillator. MCW is commonly used by RDF

beacons A beacon is an intentionally conspicuous device designed to attract attention to a specific location. A common example is the lighthouse, which draws attention to a fixed point that can be used to navigate around obstacles or into port. More mod ...

to transmit the station identifier. F2A MCW Morse can be heard on a normal FM radio receiver, and it is commonly used by both commercial and amateur

repeater In telecommunications, a repeater is an electronic device that receives a signal and retransmits it. Repeaters are used to extend transmissions so that the signal can cover longer distances or be received on the other side of an obstruction. Some ...

stations for

identification Identification or identify may refer to: *Identity document, any document used to verify a person's identity Arts, entertainment and media * ''Identify'' (album) by Got7, 2014 * "Identify" (song), by Natalie Imbruglia, 1999 * Identification ( ...

. Also, F2A is sometimes used by other types of stations operating under automatic control, such as a

telemetry Telemetry is the in situ data collection, collection of measurements or other data at remote points and their automatic data transmission, transmission to receiving equipment (telecommunication) for monitoring. The word is derived from the Gr ...

transmitter or a

remote base station A remote base station is a common name for an amateur radio auxiliary station that is controlled and operated from a remote location. Most remote base stations have similar features to any other Amateur radio station but can be controlled over a d ...

. MCW can be generated by any AM or FM radio transmitter with audio input from an audio oscillator or equivalent audio source. When an SSB transmitter is modulated by Morse code of only a single audio frequency, the resulting radio frequency emission is J2A or J2B and therefore is CW by definition, not MCW. Within the United States, MCW transmission is not permitted to

amateur radio Amateur radio, also known as ham radio, is the use of the radio frequency spectrum for purposes of non-commercial exchange of messages, wireless experimentation, self-training, private recreation, radiosport, contesting, and emergency communic ...

operators in spectrum that is restricted to CW emission types only or CW, RTTY and data emission types only, or in the 60 meter band.U. S. Code of Federal Regulations, Title 47, Chapter 1, Subchapter D, Part 97.3(c)(5), 97.305(c), 97.307(f)(14)(i)
/ref>

References

* * Morse code Radio modulation modes {{Amateur-radio-stub

See also

References