Digital circuits for generating signal sequences for linear TDMA systems

摘要

Digital circuitry comprising multiple read-only-memory (ROM) units that store predetermined data sequences are utilized to generate a digital representation of a composite signal that represents overlapping Nyquist pulses derived from input data bits. The generated signal exhibits relatively fast ON/OFF transitions. At the same time, control signals applied to the outputs of the ROMs insure that the representation preserves prespecified tail portions that minimize spectral spreading in a time-division multiple-access (TDMA) system. Once version of the circuitry generates a digital representation of a baseband signal derived from a single stream of input data bits. Another version of the circuitry generates a digital representation of a quadrature-phase-modulated carrier derived from two independent input data streams.