Chapter 3
Specification of Emissions
3.1. Classification of emissions and necessary bandwidths
The necessary bandwidth, as defined in section 1.7 and determined in accordance with the formulae and examples, shall be expressed by three numerals and one letter. The letter occupies the position of the decimal point and represents the unit of bandwidth. The first character shall be neither zero nor K, M or G. The Necessary bandwidths:
between
0.001 and 999 Hz shall be expressed in Hz (letter H);
between 1.00 and 999 kHz shall be expressed in kHz (letter K);
between 1.00 and 999 MHz shall be expressed in MHz (letter M);
between 1.00 and 999 GHz shall be expressed in GHz (letter G).
For the full designation of an emission, the necessary bandwidth, indicated in four characters, shall be added just before the classification symbols. When used, the necessary bandwidth shall be determined by one of the following methods:
· use of the formulae and examples of necessary bandwidths and designation of corresponding emissions given in Recommendation ITU-R SM.1138;
· computation, in accordance with other ITU-R Recommendations;
· measurement, in cases not covered by two above methods.
Various types of emissions, based on their basic characteristics, can be classified using three mandatory and two optional symbols. The meaning of three basic characteristic symbols is:
§ first symbol – type of modulation of the main carrier;
§ second symbol – nature of signal(s) modulating the main carrier;
§ third symbol – type of information to be transmitted.
Modulation used only for short periods and for incidental purposes (such as, in many cases, for identification or calling) may be ignored provided that the necessary bandwidth as indicated is not thereby increased.
Table 3.1. First symbol – type of modulation of the main carrier
Table 3.2. Second symbol – nature of signal(s) modulating the main carrier
Table 3.3. Third symbol – type of information to be transmitted
3.1.3. Optional characteristics for the classification of emissions
Two optional characteristics should be added for a more complete description of an emission. These are:
Fourth symbol – Details of signal(s),
Fifth symbol – Nature of multiplexing,
Where the fourth or fifth symbol is used it shall be as indicated below.
Where the fourth or the fifth symbol is not used this should be indicated by a dash where each symbol would otherwise appear.
Table 3.4. Fourth symbol – Details of signal(s)
Table 3.5. Fifth symbol – Nature of multiplexing