# 5.2 Amplitude Shift Keying (ASK)

## What is ASK?

The simplest form of bandpass data modulation is Amplitude Shift Keying (ASK). Here, the symbols are represented as various discrete amplitudes of a fixed frequency carrier oscillator. In binary ASK, where only two symbol states are needed, the carrier is simply turned on or off, and the process is sometimes referred to as ON-OFF Keying (OOK). |
| If more than two symbol states are used, then an M-ary ASK process is adopted, an example being the 8-ASK format shown here.