A new Viewer for Line Data

Line data at Rybno Geo Data can be stored by line segments or by flights. All data refer to a given time channel, generally seconds of the day in UTC from the first data item which might go beyond 86400 if a line or flight starts shortly before midnight GMT. There may be any number of channels which share this time channel and sampling time.

A program called ViewLine was developed for viewing data as profile plot and in spread sheet form simultaneously. A black marker line shows the current record position and clicking at a new position on the plot area immediately updates the spreadsheet showing the current record line high-lighted. The zoom level can be changed by dragging a rectangle, the limits will be rounded containing this rectangle at the new zoom level. Any number of zoom levels can be created this way and re-activated by clicking the zoom-in or zoom-out button.

The spread sheet part shows the data at full accuracy and right clicking gives several options like setting the black marker line, moving the line plot that it appears on the screen, or selecting a different colour. A channel can also be removed from the plot or only de-activated. Another window of the spread sheet will give some statistics like minimum and maximum, and allows for setting the vertical scale manually.

The left subwindow shows the content of the database where the channels are selected for viewing with the currently selected flight or line number shown in the status line at the bottom. Selecting a new flight (or line) will show the same channels at the current zoom level. The profiles are shown in a wrap-around fashion, the real values are shown in the spreadsheet or at the ordinate for the current channel with the ordinate always updated to match the situation where the current channel intersects with the black marker line.

The plotting of channels can be activated or deactivated at any time in the spreadsheet "Plotteries" and will be drawn in the order as activated with the last activated channel as the current channel, thus always drawn on top and not hidden by other channels.

The new Viewer showing HDF5 Line Data

The following screen shot shows ground station data at 160 Hz sampling rate, i.e. a time increment of only 0.00625 seconds, covering more than 3 days or more than 43 million data records. Thanks to the high performance of HDF5 and the efficient viewing / data source architecture of the graphical user interface framework of Qt is this program ViewLine highly responsive and convenient to use. The spreadsheet part moves for 43 million data records as fast as for a hundred records. Zooming data to any zoom level is as quick as to draw a rectangle with the mouse over the plot area, possibly repeatedly.

The green unfiltered channel has a considerable noise level from the quatization through the Larmor counter, which can not further be reduced due to quantum mechanical effects. There are 50,000 data points between each vertical grid line in this plot and therefore, the green line directly shows the full noise envelope.

The fourier domain program fourier1d of Rybno Geo Data had no problem to apply a low pass filter with a cut-off wavelength of 1/3 seconds, the result is shown in deep purple on top of the green trace.

The following screenshot zoomed into the data.

And this screenshot zoomed further into the data. The left panel with the HDF5 content has been popped away to make all area of the window available for the graphics and spreadsheet part. The separator between the spreadsheet and line plot can freely be pushed up or down leaving only a minimum space or when pushing even further leaving only one of the displays. The line plot also shows that the wrap-around solution works very clean and efficiently at all zoom levels.