Direct digital synthesizers (DDS), or numerically controlled oscillators (NCO), are important components in many digital communication systems. Quadrature synthesizers are used for constructing digital down and up converters and demodulators. They are also used for implementing various types of modulation schemes, including PSK (phase shift keying), FSK (frequency shift keying), and MSK (minimum shift keying). A common method for digitally generating a complex or real valued sinusoid employs a lookup table scheme. The lookup table stores samples of a sinusoid. A digital integrator is used to generate a suitable phase argument that is mapped by the lookup table to the desired output waveform. A simple user interface accepts system-level parameters such as the desired output frequency and spur suppression of the generated waveforms.