modulation code
Due to the many coding methods and variants, the International Telecommunication Union( ITU) and the Federal Communications Commission( FCC) have issued modulation codes for better assignment and easier handling. This is a five- digit alphanumeric code, the first three digits of which are usually sufficient to characterize the modulation.
Each digit of the modulation code represents different characteristic modulation properties. The first digit is always a letter and stands for the modulation type of the carrier frequency, the second digit is a digit and says something about the nature of the signal with which the carrier signal was modulated. The third digit is again represented by a letter and describes the information to be transmitted.
The fourth digit describes the signal characteristics; whether it is audio or video, color signals or monochromatic signals, and in the fifth the type of multiplexing. The fourth and fifth digits are represented by letters, with the letters of the fifth digit distinguishing between the different multiplexing techniques: Code multiplexing, frequency multiplexing, time multip lexing and others.
Typical examples of the three-digit modulation code used therefore look like this: A1A or F1C or J7B or K3E. A five-digit modulation code might look like this: C2FMT. The cryptic meaning can be found in the tables for the individual digits. An example would be C3F for television in amplitude modulation with residual sideband.
The modulation codes are used by the Federal Network Agency to specify which modulation type can be used in which frequency range. This applies to all radio equipment for fixed and mobile radio, directional radio and amateur radio, for professional radio, trunked radio and CB radio, for radio and television, transport radio, public and non-public mobile land mobile radio.