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User-defined Directivities

Besides of the predefined directivities user-defined frequency dependent directivities can be entered and assigned to industrial sources. To this end, select from the Tables|Libraries (global) or (local) menu the library Directivity.

Note

Note, that via the source dialogs just directivities from the local library can be selected. With global libraries, make sure that they are copied to the local library first (via button „--> Local Lib.“, table Directivity (global).

Insert a new row via the table‘s context menu and double-click into this line to open the dialog.

Directivity dialog

Dialog options

Name/ID

name and unique ID (used establish a reference the directivity object)

Type of Directivity

The dialog shows a table in which the directivity index can be entered in selectable bandwidth and in selectable angle steps. On dialog Directivity of each industrial source the directivity vector can be freely oriented (Theta, Phi) by specifying the vector‘s xyz coordinates or the rotation angles Phi/Theta/Psi, see Directivity at Industrial Sources).

  • Rotationally symmetrical: selects the input format used in former releases of CadnaA. In this case, the directivity pattern is axial-symmetrical in a plane, pointing in forward direction (0 degrees).
  • 3D Directivity: enables to enter/import full 3D directivity data as found in CLF files (see below)
  • 2D Directivity: This type of directivity is invariant of the angle Theta. It is intended to be mainly used in conjunction with optimizable sources.

Angle Step

selectable angle stepping in 5, 10 or 15 degrees

Type of Spectra

selectable for 1/1 octave band width or 1/3 octave band width

Table View

The options on this list box depend on the type of directivity selected.

The table shows with directivity type:

  • Rotationally symmetrical: value (dB) at frequency (Hz) and angle Theta (°)
  • 3D Directivity: value (dB) for selectable angle Phi (°) at frequency (Hz) and angle Theta (°) or selectable frequency (Hz) at angles Theta (°) and Phi (°)
  • 2D Directivity: value (dB) at frequency (Hz) and angle Phi (°)

Button „New“

inserts a new directivity into the Directivity table

Button „Import“

Enables import of

When importing a CLF file, the name is set based on the contents of the file and additional information is copied to the directvity‘s memo-window.

Button „Paste“

pastes a dataset from the clipboard into the table

Button „3D“

opens a 3D dialog showing a directivity balloon

The balloon is displayed in wire-frame representation and is using by default the color palette (see Color Palettes) assigned to the first evaluation parameter.

The coordinate axes XYZ are shown in red, green and blue (representing RGB as a sequence).

Directivity pattern in 3D balloon view

The scene can be controlled as follows:

  • press and drag the left mouse button to rotate the pattern
  • press and drag the right mouse button to zoom in/out the pattern
  • use the mouse wheel to step through the 1/3 octave bands (below the lowest and above the highest bands the A-weighted value is displayed). The selected band is displayed on the title bar.

Defining the directivity vector visually

In case the 3D-view has been opened within the point source’s Directivity dialog the polar angles Phi and Theta can be adjusted by pressing the SHIFT-key and dragging with the left mouse button down and adjust Psi via SHIFT-key and the right mouse button.

Option „normalized“

With the option „normalized“ activated, the directivity correction is increased or reduced by a constant factor for all directions in a way that the sound power level specified on the source dialog remains unchanged with this directivity selected.

This option enables to enter octave/third-octave band sound pressure levels having been measured in the vicinity of the source. In this case, the entered values are not changed, but maintained.

Option „Do NOT interpolate between angles“

With this option deactivated, CadnaA interpolates linearly between the values entered, whereby angular steps without input value are considered as 0 dB.

With the option activated, no interpolation will occur. Consequently, the entered values apply to the entire respective angle sector (e.g. with 15 ° steps and for the 0° direction: from -7.5° to +7.5°).

Example: This rotationally symmetrical directivity causes the following directivity pattern on a 360° full circle (vector 1: x/y/z = 1/0/0).

option „Do NOT interpolate between angles“ ON: no interpolation occurs within angular sectors Option „Do NOT interpolate between angles“ OFF: interpolation occurs within angular sectors

Note

The automatic filling feature generating intermediate values - used in former CadnaA versions - is no longer available (due to the lack of a reasonable rule for 3D directional directivities). It is recommended to interpolate any missing intermediate values using an external software and pasting the data via the clipboard.

Paste

Clicking the „Paste“ button enables to paste data formatted as text (ASCII format) with tabulators (TAB) as separators for columns and RETURN for rows from the clipboard into the dialog table. The data may either use decimal points or decimal commas.

The data is always inserted starting from the upper left cell (0° at 31.5 Hz). The current cursor location is not relevant. Therefore, the data should be formatted correctly by inserting missing octaves or angular steps by empty columns or rows.

Import of directivities via ODBC

Note

From release 2019MR1, and for the time being, the imported of directivities using the ODBC/XLSX connection is restricted to the directivity type „Rotationally symmetrical“.

Rotationally symmetrical directivities can be imported via the ODBC connection (see Database Import (ODBC & XLSX)). To this end, select from the dialog File| Database|Definition the object type „Directivity“ (at the end of the list).

The attribute of the directivity index has the structure „Sxxx_yyyy“ where:

  • xxx: angle 0 to 180 degrees
  • yyyy: frequency 31 to 8000 Hz