Application of dds in communication base station inverter

What is direct digital synthesis (DDS)?

With the widespread use of digital techniques in instrumentation and communications systems, a digitally-controlled method of generating multiple frequencies from a reference frequency source has evolved called Direct Digital Synthesis (DDS). The basic architecture is shown in Figure 1.

How is a DDS signal selected?

The signal generated by the DDS is composed of a number of image frequencies in addition to the fundamental frequency. Figure 4 C illustrates the spectrum for the case of DDS (I). So far, it has been implicitly assumed that the fundamental wave is selected by cutting off the image components using a low-pass filter.

What is a DDS ad9850?

DDS systems such as the AD9850 provide an excellent method of generating the sampling clock to the ADC, especially when the ADC sampling frequency must be under software control and locked to the system clock (see Figure 6).

What is a practical DDS system?

A practical DDS system implements this basic function in a much more flexible and efficient manner using digital hardware called a Numerically Controlled Oscillator (NCO). A block diagram of such a system is shown in Figure 2. The heart of the system is the phase accumulator whose contents is updated once each clock cycle.