Spectrum Curves Dialog

Controls: Spectrum Dialog >> Curves
Macro: SpectCurve

This button opens a dialog that allows you to apply a weighting curve to the data displayed in Y-log (power spectrum) mode.

The same dialog is opened by the Weighting Curve button in the Sound Level Meter option to select a Standard weighting curve, or a custom curve you create.

The top 'Y-log' button in the dialog is a duplicate of the button in the parent Spectrum dialog. You can also use ALT+Y to toggle this at any time.

A curve changes the displayed data (but not the raw data) as if an arbitrary-response filter had been applied to the original waveform, increasing or decreasing the response at different frequencies.

Curves are not stored with or associated with .DQA, .WAV, or .DAT data files. When you open a data file, it uses current curves, if any, not those that might have been active when it was saved. (.TXT files, however, always reflect whatever is shown on the trace, including any active curves.)

Curves have no effect upon linear magnitude spectrum or waveform displays. However, they do affect the Spectrogram display and Pitch Track operation, but only if Spectrum Y-log is active as for a normal Spectrum display.

In DaqMusiq mode, if both the Generator and Input are off, an internal "white" random source is supplied to the Left Out channel to drive Pitch Track. You can apply Curves to this channel to change the spectral shape.

Curves may be supplied as files, or created in memory via macro commands, or you may use an arbitrary dB/octave Tilt 'curve'. Each channel may have only one curve applied to it at a time, but you may have a different curve for each channel. You can also apply the same curve to more than one channel.

• Weighting Curve Files
  • .CAL or .FRD Files as Curves
• Standard Weighting Curves
• Mirror Curve Files
• Memory Curves
• Tilt +/-dB / Octave

Macro Notes:

SpectCurve=1 opens the Spectrum Curves dialog, SpectCurve=0 closes it, and SpectCurve=x toggles between open and closed.

This command only works if the Spectrum dialog is already open.

Note that you do not need to open the Curves dialog to change its controls directly via macro commands.

LI.SpectCurve#X= (value ignored) allows you to unselect any Curve or Tilt that is currently active for the Left Input channel (LI.). Use an RI. prefix for Right In, LO. for Left Out, RO. for Right Out, or Ch. for whatever channel was previously specified via the Ch Channel Select command.

To find out if a specified channel such as LI is using a Curve or Tilt, assign a variable to LI.SpectCurve?X. The variable will be -1 if the Left Input is not using any Curve or Tilt; otherwise it will hold the Curve number 0-3, or else 4 for Tilt.

See also Spectrum Control Dialog