Data Display

Two main charts display the spectrographic data. The top window, Chart #1, shows each and every scan line that received from the WCCRO Spectrograph. New scan lines are added on the right side of the window and previous lines are scrolled to the left to make room for the new line. Scan lines that are pushed off the left side of the window are not retrievable in real time, though they may be recovered if the data is being saved. The program does not save more data in memory than can be displayed on a single screen.

Two hundred channels of data, each one pixel in height stretch from the top of the display window to the bottom in order of decreasing frequency. There is a legend on the right side of each display window showing the frequency span. The top and bottom frequencies may also be read in the Hi F and Lo F boxes in the upper right of the main window.

The color displayed for a particular channel is primarily dependent on the strength of the signal received by the FS200 for that channel and how this signal strength is mapped to a selectable "color file". Several color files are available to experiment with. These are text files of RGB (Red Green Blue) values. Each color file has 4096 values, even though the present version of the FS200 only uses 1024 of these values (every fourth value). By experimenting with different color files you can achieve a view that is pleasing and best suited for discerning details of the spectrum. You may select a color file via options under the Color, or File menu options on the main Spectrograph Viewer window.

Note that no matter what color file or other display options you use when viewing the real time data stream, the raw data is unaffected. If you save the data, you can later apply other viewing options while reviewing the file. There are a few methods that can be applied to affect the way the colors are "mapped" to the various data values. These will be discussed further below.

The bottom spectrograph display, Chart #2, by default displays data averaged from ten spectrum sweeps in each of its vertical pixel columns. Thus this display advances at one tenth of the rate of the upper display. This arrangement has three positive effects. It allows approximately 600 seconds of data to be seen at once, a reasonable amount of time to see structures such arcs in Jovian noise storms. Averaging the data has also been demonstrated to suppress some types of interference such as power line buzz and to increase sensitivity. Both top and bottom charts have independent time scales below them.

This may be a good place to note that the times displayed below the charts are dependent upon the system clock on the client computer and the offset provided by the time zone setting. No time stamps are sent by the server software. The accuracy of the timing for a file ultimately rests with the client. Synchronization of the computer clock with online timeservers is suggested.

A second display option exists for Chart #2. By selecting View / Scope View from the main Spectrograph Viewer window menu, Chart #2 will assume the appearance of a standard spectrum analyzer display where the X axis is frequency and the Y axis is the raw signal strength value. This display updates for every new scan (approximately 10 scans /sec) , but due to buffering may appear to update somewhat erratically except on a very fast computer. The Scope View drawing process is intensive and so when using this option, one should keep an eye on the buffer indicator to be sure that the buffer length does not begin to increase.