The theorem developed by Harry Nyquist and published in his 1928 paper entitled "Certain Topics in Telegraph Transmission Theory."The Nyquist theorem states that an analog signal waveform can be converted to digital format and be reconstructed without error from samples taken at equal time intervals if the sampling rate is equal to, or greater than, twice the highest frequency component in the analog signal. The Nyquist theorem forms the basis for pulse code modulation (PCM), the fundamental method for converting analog voice to digital format. See also Nyquist, Harry and PCM.