Classification of emissions

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Emissions are classified and symbolised according to the following characteristics

1. Type of modulation of main carrier

2. Type of transmission

3. Supplementary characteristics


1. Types of modulation of main carrier

a. Amplitude A

b. Frequency (or Phase) F

c. Pulse P

2. Types of transmission

a. Absence of any modulation intended to carry information 0

b. Telegraphy without the use of a modulating audio frequency 1

c. Telegraphy by the on-off keying of a modulating audio frequency or audio frequencies, or by the on-off keying of the modulated

emission (special case an unkeyed modulated emission) 2

d. Telephony (including sound broadcasting) 3

e. Facsimile (with modulation of main carrier either directly or by a frequency modulated sub-carrier) 4

f. - line missing -

g. Four-frequency diplex telegraphy 6

h. .Multichannel voice-frequency telegraphy 7

i. Cases not covered by the above 9

3. Supplementary characteristics

a. Double sideband (None)

b. Single sideband

-reduced carrier A

-full carrier H

-suppressed carrier J

c. Two independent sidebands B

d. Vestigial sideband C

e. Pulse

-amplitude modulated D

-width (or duration) modulated E

-phase (or position) modulated F

-code modulated G

Reference: I.T.U.






acceleration due to gravity (m/s2)


moment of inertia of a buoy about the axis through the centre of gravity in kg*m

Centre of buoyancy


Celsius (previously Centigrade)


diameter at the waterline (m)

change in the value of a term

Solar declination angle (in degrees)

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centre of gravity

charge current


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roll period


International Association of Marine Aids to Navigation and Lighthouse Authorities - AISM