Determining Short Time Intervals Between Pulses
Original Publication Date: 1978-Jul-01
Included in the Prior Art Database: 2005-Feb-21
The Fourier transform G of a single pulse has the general shape shown in Fig. 1. The Fourier transform of a doublet (two closely spaced identical pulses) has the general shape G' shown by the solid line in Fig. 2. (The envelope of the Fourier transform of the doublet, shown by the broken line in Fig. 2, has essentially the same shape as the Fourier transform of the single pulse.) The zeros (minima) of the Fourier transform of Fig. 2 are related to the time separation T of the pulses by the relation T = (2n + 1) / 2f(n), where n equals 0, 1, 2, 3... A derivation of this relationship may be found in W. P. Alford and A. Gold, "Laboratory Measurement of the Velocity of Light," American Journal of Physics 26, 481 (September 1958).