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AbStJWtBased on a polyphase IFFT filter bank in the transmitter and a polyphase FFT filter bank in the receiver orthogonal multiple carrier data transmission with high computational effectivitiy and high bandwidth efficiency can be achieved (OMC data transmission system). The orthogonality is conditioned by an ideally sampling of the receive vector a t proper time instants. This paper deals with the effect of the filter transfer function characteristic t o the amount of signal distortion due t o nonideal timing recovery (timing synchronization) in the receiver. A special class of Nyquist systems is introduced and an optimum low-pass filter transfer function for the polyphase filter bank of the OMC data transmission system is given.

The progress in the field of digital signal processing leads to the development of digital multirate techniques. Due to the fact that every single part of the whole system is processed with a minimum sample rate these techniques result in a very advantageous realization of a digital system with respect to the required processing time. In this paper a systematic procedure is shown leading to an efficient implementation of such multirate systems by digital signal processors. With the introduction of appropriate measures it is possible to make statements about the efficiency of the implementation with respect to the available arithmetical capacity of the signal processor. The presented method is demonstrated by the example of the implementation of a voice frequency telegraph FSK‐modem by a digital signal processor.