XTA apa-4e8, Руководство оператора

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Page 74 APA-4E8 Operator’s Manual
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Bandpass Filter
The bandpass filter has adjustable
frequency and‘Q’ (or Bandwidth)
controls. These affect a range of
frequencies symmetrically about the
centre freqency as shown in the graph,
gradually cutting the level, but
providing no gain.
Remember that ‘Q’ is 1/Bandwidth, so
the higher the ‘Q’, the lower the
Bandwidth, and the smaller the range
of frequencies affected.
Note that the response is fundamentally NOT a flat-topped response (so it is not constructed
from a high pass and low pass). See previous page for details of how to construct a flat-
topped filter response.
Notch Filter
The notch filter has adjustable
frequency and ‘Q’ (or Bandwidth)
controls. These affect a range of
frequencies symmetrically about the
centre freqency as shown in the graph.
Remember that ‘Q’ is 1/Bandwidth, so
the higher the ‘Q’, the lower the
Bandwidth, and the smaller the range
of frequencies affected. The notch filter
depth varies with bandwidth — the
wider the filter, the lower the depth
will be.