A method of semiautomatic specification refinement and program generation using library modules, is described. Users write their specifications and modify and rearrange them so that they can be refined with the aid of the library modules. When a specification is given, a refinement system, called MAPS (module-aided program construction system) searches for library modules applicable to the given specification, replaces the specification with a more detailed description written in the operation part of the modules, and converts the refined specification into a program written in a programming language designated by the user. Case-like expressions or pseudo-natural language expressions are used for describing user's specifications and specifications for library modules.>

This paper presents the power spectrum of the transmitted signal in a synchronous spread-spectrum communication system in which the users' information symbol sequences are encoded intoM-ary channel symbol sequences. Furthermore, when maximal-length shift register sequences are used as the spreading code sequences of the system, the average power spectrum over all possible sets of the allowable simultaneous users is presented. It is shown that distribution of the spectrum is influenced considerably by the spreading code and the channel symbol sequences.

Using the direct method of analysis, the power spectrum of the output phase rate of a FDM-FM signal passed through a transmission system with AM-PM converter is expressed by four kinds of components for both cases with and without preemphasis. It is illustrated that signal-to-interference ratios are in good agreement with Monte Carlo computations. Further, based on the evaluations of the spectral components and mean-square error, in baseband, the effects of these components are elucidated.