The correlation function is derived of noise with a 1/f spectrum betwe
en a low-frequency Sr and a high-frequency fh. The essential term in t
he correlation function is a - ln t term. The usual interpretation of
1/f noise as a summation of Lorentzian spectra is discussed. The model
of 1/f noise from a random series of t(-1/2) pulses is correct. The -
ln t correlation function is also derived from such a series.