Research On Efficient DDC

Software wireless makes the radio function realized by hardware through software, which improves the flexibility of the system. But software wireless need transform the high-speed data flow into the low-speed flow of data, then deals with the signal. Digital down-conversion can accomplish this transformation. However, the efficiency of the traditional digital down-conversion is not high. In order to improve the efficiency, this paper investigates and implements a high-efficiency digital down-conversion.Digital down-conversion is mainly consist of orthogonal digital frequency mixing, filtering, extraction, compensation and plastic modules. The high-speed data flow can be tansformed into the low-speed flow of data through these modules. In order to realize a high-efficiency digital down-conversion, the CIC filter module of digital down-conversion is improved in this paper. According to the inadequacy of CIC filter performance. Based on the study of the COSINE filter, this paper uses the property of COSINE filter stop-band attenuation value larger than CIC filter's to improve CIC filter. Stop-band attenuation of improved CIC filter increase 34.16dB through COSINE filter,and use ISOP to reduce pass-band attenuation of CIC filter, the last achieve an efficient algorithm of digital down-conversion by the modified CIC filter.This paper adopts the MATLAB of Math Works and the DSP of TI company to develop the proposed function. Matlab Link for CCS Development Tools developed by Math Works and TI company has realized the connection of the two development environment. Based on the development environment,designed an efficient digital down-conversion system,and the various modules of this system was simulated,the result of experimental met the requirements.