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This is an old revision of this page, as edited by LSMFT (talk | contribs) at 21:04, 11 September 2020 (Correction to MCW below 50.1 MHz in U.S. amateur service - see US code title 47 part 97.3(c)(5), 97.305(c); miscellaneous corrections; delete broken link source). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Passband modulation
Analog modulation
AM FM PM QAM SM SSB
Digital modulation
ASK APSK CPM FSK MFSK MSK OOK PPM PSK QAM SC-FDE TCM TC-PAM WDM
Hierarchical modulation
QAM WDM
Spread spectrum
CSS DSSS FHSS THSS
See also
Capacity-approaching codes Demodulation Line coding Modem AnM PoM PAM PCM PDM PWM ΔΣM OFDM FDM Multiplexing
v t e

Modulated continuous wave (MCW) 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.

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 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 stations for identification. Also, F2A is sometimes used by other types of stations operating under automatic control, such as a telemetry transmitter or a remote base station.

MCW can be generated by any AM or FM radio transmitter with audio input from an audio oscillator or equivalent audio source. MCW transmission is not permitted to amateur radio operators within the United States in spectrum that is restricted to CW emission types only or RTTY and data emission types only, or in the 60 meter band. 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.

See also

• Morse code
• Prosigns for Morse code
• Types of radio emissions

References

1. An MCW Keyer for V/UHR FM (N. Wilford, W1TLZ), QST April 2013, pp. 37-38
2. PicoKeyer-Plus Kit
3. 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)
4. U. S. Code of Federal Regulations, Title 47, Chapter 1, Subchapter D, Part 97.3(c)(1)

• "Amateur Radio Service Definitions (47 CFR §97.3)". Retrieved August 3, 2005.
• "Ham Radio Jargon, Abbreviations and Terminology". Archived from the original on September 19, 2017. Retrieved August 3, 2005.

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