| 摘要 |
Digital filter ( 104 ), comprising: a first frequency shifting mechanism ( 106 ) configured to shift an input spectrum (H(f)) of an input signal ( 100 ) by a first frequency distance (F 1 ) to obtain a shifted frequency signal ( 122 ) with a shifted spectrum; a filter ( 108 ), configured to filter said shifted frequency signal with a predetermined transfer function to obtain a filtered signal ( 130 ); and a signal processor ( 110 ), said signal processor including: an adder ( 202 ), and at least a second frequency shifting mechanism ( 222 ), said signal processor ( 110 ) being configured to generate an output signal ( 140 ), which is a sum of said filtered signal ( 130 ) and said shifted frequency signal ( 122 ) and said output signal ( 140 ) has an output spectrum, which is shifted by a second frequency distance (DF) with respect to said shifted spectrum, wherein said second frequency distance (DF) is independent of said first frequency distance (F 1 ).
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