# ITU Modulation Codes RNAV

Each of the radio beacons in the Radio Navigation syllabus, together with the two types of voice transmission (VHFVHF —Very High Frequency and HFHF —1) Radio Waves: High Frequency2) Human Performance: Human Factors), has its own code based on the way it is modulated and the type of information it contains.

There are three symbols in each code. In order, they are:

1. Type of modulation (M)
2. Type of modulating signal (S)
3. Type of information (I)

The mnemonic MSI (as in the computer company) can help you remember the order.

You need to know firstly, what the code for each beacon you will learn about in RNav is. Secondly, you need to know what each character represents, but not what each individual letter stands for. For example, you need to know that the ILSILS —Instrument Landing System is A8W and that the first letter is the type of modulation, but not what A8W itself means.

The ITUITU —International Telecommunications Union categorises modulation with various numbers and letters, such at A1A. With a three digit code, what does the first character in this sequence mean?