Going over to the Paley-Wiener space B we are able to guarantee, in addition, that the reproducing kernels form an orthonormal system with discrete othogonality property(see(39-42).7. All Routes to Sampling Expansions Lead to Reproducing KernelsThe classical proof of Shannon sampling theorem is based on the inverse of the Fourier integral and complex Fourier series. Suppose that the signal F defined on the real line is square integrable and bandlimited, say to . Then F can be expressed as the inverse of the Fourier transform F, where now the integration is over Fz. We extend F periodically to the real