A spot noise generator includes a mask component, a polyphase synthesizer, a first signal channel and second signal channel. The mask component has a narrowband noise input, a desired frequency channels word input, a first channel output and a second channel output. The narrowband noise input signal is a digital narrowband noise signal sampled approximately at the Nyquist rate. The desired frequency channels word selects one of the group consisting of the first channel output, the second channel output and a combination of the first channel output and the second channel output. The polyphase synthesizer synthesizes the first channel output signal, synthesizes the second channel output signal and outputs a desired noise signal based on the synthesized first channel output signal and the synthesized second channel output signal.