Waveform Fundamentals
Direct Digital Synthesis

The Standard Function mode is implemented through direct digital synthesis (DDS).

The following figure shows the building blocks for DDS-based waveform generation.

You can use the lookup memory in Function Generation mode only. You cannot use the lookup memory in Arbitrary Waveform Generation mode. You can store one cycle of a repetitive waveform—a sine, triangular, square, or arbitrary wave—in the lookup memory. Then, you can change the frequency of that waveform by sending just one instruction. You can use Function Generation mode for very fine frequency resolution function generation. Because Function Generation mode uses an accumulator, waveform generation loops back to the beginning of the lookup memory after passing through the end of the lookup memory.

In Function Generation mode, each stage is made up of two instructions: the frequency and the time. The frequency instruction specifies the frequency of the waveform generation. The time instruction specifies the amount of time that the frequency generates.

Note  You cannot specify the number of iterations for a waveform to generate in Function Generation mode.