| 摘要 |
In a sampling rate converter for converting a sampling frequency L of a digital signal to a sampling frequency M (L:M conversion) or for converting a sampling frequency M of a digital signal to a sampling frequency L (M:L conversion), the same filter coefficients are utilized and a constant predetermined DC gain is maintained for both conversions. An over-sampler multiplies the sampling frequency L or M by M or L, respectively, during the L:M conversion and the M:L conversion, respectively. A filter, which receives the output of the over-sampler, restricts the frequency band of the output. A CPU supplies filter coefficients to the filter and performs such functions as quantizing the filter coefficients, arranging the quantized filter coefficients into a three-dimensional array including rows and columns, determining a ratio between a total sum of values of the rows and columns of the array of quantized filter coefficients, and correcting each of the quantized filter coefficients in response to the determined ratio so as to maintain the predetermined DC gain. A down-sampler receives the output of the filter for multiplying the rate converted frequencies by 1/L or 1/M during the L:M conversion or the M:L conversion, respectively.
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