IEEE paper for project

IEEE paper for project - 7 34 I EEE TRANSACTIONS ON...

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734 IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. COM-26, NO. 5, MAY 1978 Digital TDM-FDM Translator with Multistage Structure Abstmct-In this paper, a new digital signal processing algorithm for the digital TDM-FDM translator is proposed. The digital TDM-FDM translator, which performs a direct translation between two multiplex formats in the telephone network (time-division- multiplexing (TDM) and frequency-division-multiplexing (FDM)) by using digital techniques, has advantages in accuracy and stability of characteristics over equivalent analog equipments. However from the economical point of view, it largely depends on the cost reduction of semiconductor devices and LSI technologies. The proposed algorithm can be realized using only two digital filters and does not require product modulators or Fast Fourier Transform (FFT) processors. The required number of multiplications, which is closely related to the quantity of hardware, is considerably reduced by the multistage structure of this algorithm. The reduction in the kind of required digital hardware and the required number of multiplications makes it possible to efficiently utilize the new hardware realization techniques of digital filters or multipliers using read-only memories and simple logic devices. Since it is foreseen that cost reduction of memory devices will be more rapid than that of logic devices, the proposed algorithm is expected to be advantageous with regard to cost over existing algorithms where complex multiplier logic is required. estimation of the computation rate,is carried out with reference to a practical case. The computer simulation results are also shown. 1. INTRODUCTION ITH introduction of digital communication tech- niques to telephone networks, which were hitherto entirely analog, two kinds of multiplex systems, Frequency- Division-Multiplexing (FDM) and Time-Division-Multiplexing (TDM), now coexist in a network. In order reasonably introduce integrated digital network, it is necessary to effi- ciently achieve the connectionsbetween time division switching equipments and analog transmission lines or between digital transmission lines and analog transmission lines, etc. The digital TDM-FDM translator makes it possible to trans- late between TDM and FDM directly at multiplex level by using digital signal processing techniques. This has been inuesti- gated at several institutes laboratories for past several In the direct method of digital TDM-FDM translation, when number of translated channels is large, many multipli- cations are required. Since a high-speed multiplier requires highly complex hardware, investigations of the digital TDM- FDM translator have been mainly devoted to reduction of the required number of multiplications. years.[l1-[41 .I101 number of translated channels N is equal to 2' (I: integer), where K denotes the required number multiplications per channel.
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IEEE paper for project - 7 34 I EEE TRANSACTIONS ON...

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