SPECTROGRAM

The data in current plot can be plotted as spectrogram.

spectrogram

Only spectra (i.e. dimension 1 data) can be plotted as a spectrogram.
One example of spectra is the output of the fft operator when applied in the Calculator, (p0y = fft(q0)).

Only one spectrogram can be plotted in each panel. It is possible to plot time series at the top of a spectrogram.

The spectrogram is controlled from the Spectrogram Dialog.

When pressing the Grahics->Plot->Spectra in the igr menubar the Spectrogram Dialog appears.

The options in the Spectrogram Dialog :

Used
The Used radio buttons is used to set spectrogram on or off for the current plot.
After the Ok (or Update) button is pressed the user must either press Update in the ctm time manager, or press the right mouse button in the panel containing the spectrogram.
Zaxis
The Zaxis radio buttons determines the amplitude scale (i.e. the color scale) maximum and minimum.
When the preset button is pressed the maximum and minimum of the color scale are given from the data base server.
When auto is pressed the maximum and minimum are computed from the data.
When manual is pressed the user inputs the maximum and minimum values in the input lines Zaxis amplitude, minimum and maximum .
spectrogram selection
LinLogZ
The LinLogZ radio buttons determines if the data is plotted at a linear or logarithmic z-axis (i.e. color) scale.
When the preset button is selected the scale type which was delivered by the data base server is used.
When the lin button is pressed the data is always plotted at a linear scale.
When the log buttons is pressed the data is (if possible) plotted at a logarithmic scale.
In the case Zaxis=manual and LinLogZ=log is selected, the numbers in the input lines Zaxis amplitude, minimum and maximum are the logarithmic (base 10) of the maximum and minimum values used for the color scale. As an example if the user input -3 and 1 in the Zaxis amplitude minimum and maximum respectively, the color scale will be from 0.001 to 10.0 .
SizeX
The SizeX radio button determines the horizontal size of the spectrogram, (i.e. columns).
When SizeX auto is selected the number of columns in the spectra is the number of samples/spectra returned from the data base server, (or in the case of fft from the Calculator).
When manual is selected the user inputs the number of columns in the spectrogram using the Spectrogram size, X (columns) input line. When selecting manual SizeX the client automatically selects manual Zaxis.
SizeY
The SizeY radio button determines the vertical size of the spectrogram, (i.e. rows).
When SizeY auto is selected the number of rows is the number of bins in each spectra. (Number of elements in the array.)
When manual is selected the user inputs the number of rows in the spectrogram using the Spectrogram size, Y (rows), input line. It is also possible to start the spectrogram at a higher bin in the spectrogram than the first one. In this case the user input a number greater than 0 in the Y start line.
As an example suppose we have a spectra containing 200 bins. If the user only wants to plot the data in bin 100 to 150 he select size Y (rows) = 50 and Y start = 100 .
TimeGaps
Some quantities are only sampled in short intervals with gaps between. In the spectrogram these gaps can be closed when the filled button in the TimeGaps radio buttons is selected.
FillRows
Some data sets have not a uniform distribution along the first dimension (i.e. along the x-axis when plotting the data as line plot). The plotting of these data in a spectrogram will result in empty rows. In order to fill these empty rows the filled button in the FillRows column is selected.

When plotting data from a big time interval the user might use the Continuous utility in the ctm time manager. In this case the user must first select manual size of the spectrogram. See also Help in the Page Control Dialog.

The color of the spectrogram is selected from the IgrColorSelect dialog. The IgrColorSelect dialog is shown when Graphics->Panel->Color->Spectra is pressed.

color spectrogram The IgrColorSelect window is used to select colors for the spectrogram. The left button is used to select number of colors. When the user press this button, the Select Color Nr window appears. Here the user can select number of colors for the spectrogram. Press Apply after the selection.
The second button from the left is used to inverse the color table. The button toggle between NRM and INV when pressed. The user can see the effect at once in the colorbar at the bottom of this window.
The third button from the left contains the selection of color table. When pressed the SelectTable window shows up. Here the user can select between different color scales. As before the selection changes at once the colorbar at the bottom of the IgrColorSelect window.
When the Done button is pressed the IgrColorSelect window disappears.

The postscript plot of the spectrogram is always in the selected color. The color selection in the Print Dialog has no effect on spectrogram.

It is possible to plot time series and spectrogram in the same panel. In this case the user must use the Panel Control Dialog and set the Scale to individual.

When the OK button is pressed the spectrogram is updated and the Spectrogram Dialog disappears. When the Update button is pressed the spectrogram is updated, and when the Cancel button is pressed the Spectrogram Dialog disappears.
After the Ok (or Update) button is pressed the user must either press Update in the ctm time manager, or press the right mouse button in the panel containing the spectrogram.

spectrogram info If we want to plot data that has unequal sampling intervals the spectrogram will not show correct time line. In this case a warning window appears. The user has then in the Spectrogram Dialog to set SizeX to manual and set a useful big number ( not bigger than the horizontal resolution of your screen ) in the the Spectrogram size, X (columns) input line.

In the case when in the Page Control Dialog the use small ticks in the log. axis is selected, the major tick marks with labels are written on the color scale for each number being a multiply of 10. Between are the smaller tickmarks for all numbers being a multiply of 1. However when the tick marks are to many the smaller are automatically removed. The maximum number of tickmarks on the color scale before the small one are removed is 40 (INSPECT_MAX_COL_STICKS).


Updated June 28, 2006 by Bjørn Lybekk