Digital Filter

The figure displays the filter settings window. Diagram AFC of the filter to be calculated occupies the major portion of the window.

The horizontal axis of this diagram is the frequency axis.

The vertical axis is the gain axis, the scale of which can be either a multiplication factor or decibels.

Necessary AFC is constructing by using the mouse. Diagram AFC consists of the reference points and straight lines connecting these reference points. That is, the gain values between the user-defined reference points are calculated by linear approximation.

AFC construction starts when adding new reference points by clicking the line (if the mouse cursor is over the reference point or line the cursor takes a hand form). Upon clicking the line new reference point appears, which can be moved both vertically and horizontally (except for the end reference points) - but not further than the adjacent reference points.

To move the reference point(s) it is necessary to drag it with the mouse cursor, which has to take a 'hand' form, and then left click and start moving the reference point in the selected direction when holding the left mouse button pressed. When moving the reference point both of the current coordinates will be shown on the status panel: gain and frequency factors. To delete a reference point, point at it with the mouse cursor and left click when holding the Ctrl key pressed.

In the upper part of the filter settings window there is the tools panel. At the top of the tools panel there is a row of buttons that allow undoing the changes made, as well as reading the filter parameters from the file and saving the filter parameters in the file.

Button determines dimension of the vertical axis if the button is pressed then the axis is in terms of decibels otherwise the axis is in terms of multiplication factors.

Input field "Kmax" and "�min" sets the limits of the vertical axis either in times or in decibels.

Button determines the scaling of the vertical axis: either linear or logarithmic. If the button is pressed then the frequency axis is logarithmic otherwise it is linear.

Input field "Fmax" is the maximum value of horizontal axis frequency.

Button determines the filter settings and closes the work window.