For pt.I, see ibid., vol.41, no.3, p.502-208 (1993). Properties of a specific class of interpolators that are based upon polynomials are discussed. Several implementations are described, one of which is particularly convenient in practical hardware. Simulations demonstrate that simple interpolators give excellent performance. In many cases, two-point, linear interpolation is adequate. If better performance is needed, classical four-point, third-order polynomials could be used. Better yet, a novel four-point interpolating filter with piecewise-parabolic impulse response can have performance superior to that of the standard cubic interpolator and still be implemented much more simply. The NCO-based control method presented in Part I is shown to be equivalent to a conventional phase locked loop and its operation is verified by simulation.>

The limiting factor in the use of computer tools for the design of communications systems is often the amount of human intervention needed, rather than the actual computation time. A technique is presented by which a large proportion of the low-level decision making is delegated to the computer, thereby allowing the designer to concentrate on the engineering aspects and higher-level tradeoffs. The implementation described can be used with existing design programs (e.g., transmission simulators). The possibilities and limitations of the technique are discussed, and several examples of its application are given.>