The principle of DDS is mainly to c

The principle of DDS is mainly to control the phase increment of points, that is to say, a single periodic sampling point is fixed and stored in memory, and the waveforms of different frequencies correspond to different phase increments. As shown in Figure 3.2 sine wave, we reconstruct the signal with phase increment π / 4 and π / 8 respectively. We assume that the phase accumulation is carried out under the same clock beat. As shown in Figure 3.2, the influence of different phase increments on the frequency of reconstructed signal, a is the curve generated by the phase increment of π / 4, and B is the curve generated by the phase increment of π / 8, so it is easy to find that when the phase increment is reduced by a factor of two, the output signal strength of the sampling value is twice the difference, and the relationship between the period and the frequency is reciprocal, so the frequency relationship of the output signal in two cases can be obtained. In this way, signals of different frequencies can be obtained.