Pseudo-random signal synthesizer with smooth, flat power spectrum

摘要

Apparatus and a method are disclosed for synthesizing a pseudorandom communications signal having a smooth power spectrum. The system (21) comprises frequency modulation circuitry (31, 33, 35) for deriving a first analog signal (S(u)) from a digital encoding signal (PN). The first analog signal is derivied to have a substantially constant amplitude and a frequency varying in response to the amplitude of the digital encoding signal. Frequency to time transform eg. Fourier transform circuitry (37) is connected to the modulation circuitry and is operative to derive a second analog signal (S(t)) from the first analog signal (S(u)). The resulting second analog signal has a substantially constant or smooth power spectral density over the bandwidth of said second analog signal, and an amplitude that varies in response to the amplitude of the digital encoding signal.