| 摘要 |
<p>A filter structure (Figure 4) including a notch filter (C) designed to have a transmission zero at a frequency slightly displaced from one half of the lower sampling rate of the interpolator/decimator, and thus providing increase in attenuation at the half-rate frequency.</p><p>The notch filter (C) is comprised of two like all-pass-network filters (31 and 33) and has feed forward and feedback connections (39 and 41), the latter connection (41) including a coefficient multiplier (43).</p><p>The feedback connection (41) is made between a tapped output (T) of the second of the network filters, filter (41) and an input node (35).</p><p>Thetapped filter (33) is characterised by throughput and a tapped output transform functions X(Z) and Y(Z) given by the following expressions:-<MathDetails id="matha01"><MathText><![CDATA[ <img id="ia01" file="imga0001.tif" wi="41" he="4" img-content="math" img-format="tif" inline="no" /> ]]></MathText></MathDetails>and,<MathDetails id="matha02"><MathText><![CDATA[ <img id="ia02" file="imga0002.tif" wi="40" he="5" img-content="math" img-format="tif" inline="no" /> ]]></MathText></MathDetails>where Z-' is the unit delay operator, K the multiplier coefficient and, a, a structure dependant constant.</p> |
