Classification of emissions (emission classes)

Classification of emissions (emission classes)

Classification of Radio Emissions According to ITU Regulations

Radio emissions are categorized based on their modulation characteristics, nature of the modulating signal, type of transmitted information, and bandwidth requirements. The International Telecommunication Union (ITU) utilizes a standard three-character designation (with optional 4th and 5th modifiers) to define any emission precisely.

1. Structure of Emission Designators (Symbols 1 to 5)

• First Symbol: Type of modulation of the main carrier.
• Second Symbol: Nature of the signal modulating the main carrier.
• Third Symbol: Type of information to be transmitted.
• Fourth Symbol (optional): Details of signals/code structure.
• Fifth Symbol (optional): Multiplexing method used.

Symbol Breakdown:

First Symbol (Modulation Type):

• N — Unmodulated carrier;
• A — Double-sideband amplitude modulation (DSB);
• H — Single-sideband (SSB) with full carrier;
• R — Single-sideband (SSB) with reduced or variable carrier;
• J — Single-sideband (SSB) with suppressed carrier;
• F — Frequency modulation (FM);
• G — Phase modulation (PM);
• B — Independent sidebands (ISB);
• C — Vestigial sideband (VSB);
• W — Combination of amplitude, frequency, or phase modulation.

Second Symbol (Nature of Modulating Signal):

• 0 — No modulating signal;
• 1 — Single digital/analog channel without modulating subcarrier;
• 2 — Single digital/analog channel using a modulating subcarrier;
• 3 — Single channel containing analog information;
• 7 — Two or more channels containing digital information;
• 8 — Two or more channels containing analog information.

Third Symbol (Type of Transmitted Information):

• N — No transmitted information;
• A — Aural telegraphy intended for human decoding (CW);
• B — Automatic telegraphy (RTTY, Teleprinter);
• C — Facsimile (FAX);
• D — Data transmission, telemetry, telecommand;
• E — Telephony (Voice — SSB, FM, AM);
• F — Television / Video (ATV, SSTV).

2. Practical Table of Amateur Radio Emission Designators