IEEE GRSS RFI Observations Viewing Tool: User's Manual

Overview

This manual describes how to use the GRSS RFI Observations Viewing Tool. The system enables users to query the online database of RFI observations from various satellite systems over the years. It then displays the results on a map and in table form.

Currently, the system includes all the RFI observed and identified by SMOS, and will soon contain interference data from the SMAP radiometer. Observations by more sensors, such as GMI and Aquarius will be added in the near future. In the longer term, plans for inclusion of RFI detected by other passive and active instruments will be considered. The system displays a circular mark at the location of each RFI observation. The diameter of this mark is related to the ground resolution of the particular instrument/band combination and the accuracy of the RFI localization. The edge of the circle is drawn using a solid color, while the interior is drawn translucent in the same color, which helps visualize overlapping observations. The interface is shown in the figure below:




The overall process to view RFI observations involves querying the database in a number of ways: The system is accessible using the URL: http://www.grsss-ieee.org/rfi_observations.html. System usage is described in the sections below.

Selecting by Country

There are 2 ways to select by country: In each case a new query is made to the database, and in a moment the old data is erased, and the new data is displayed.

Selecting by Observing Instrument

There are two ways to select by observing instrument: In each case a new query is made to the database, and in a moment the old data is erased, and the new data is displayed.

Selecting by Date Range

This feature allows a user to display RFI observations that were observed at any time during the selected time period. The user can type in a date with the format yyyy-mm-dd or can use the calendar to specify a date by clicking on it. In each case a new query is made to the database, and in a moment the old data is erased, and the new data is displayed. An invalid date range will produce no results.

Selecting by Frequency Range

This feature allows a user to display RFI observations that were observed within a given range of frequencies. The slide has two handles, one for specifying the low frequency and one for the high frequency of the desired range. The range values are displayed above, in MHz. It may be easier to select a handle, and then use the arrow keys to move it. This provides finer control.

Colorizing RFI Observations on the Map

The RFI observations are visualized using one of two different color schemes: The default is colorizing by frequency. This can be changed by clicking on the appropriate radio button. Note that the color bar, below these radio buttons, updates as well. The color bar is also clickable. Each of the colored rectangles can be clicked on to display that subset of data. For example, when in frequency mode, one can click on the green C-band rectangle to only show RFI observations whose frequencies are within the C-band range. Or, if in instrument mode, one could click on the blue SMOS rectangle to show only data from SMOS, for example. This may be more convenient than using the pull-down menus or slider for these tasks.

The Map

The map shows the RFI observations for the selected country, frequency, etc. as colored circles with translucent interiors. One can zoom in to the map using the "+" button in the upper-left, or by double-clicking somewhere in the map. One can zoom out of the map by using the "-" button in the upper-left. The user can pan across the image as well, by just clicking and dragging in the direction one wants to pan. Also, moving the mouse over an RFI observation will display some relevant information for that observation. Clicking on it, will highlight the relevant table row if more information is desired. The green button to the lower-right of the map, called "Save Map" will create a downloadable png-format image file that can be used with other software.

The Table

The table of information contains all the information from the database for each RFI observation that matches the query. Each of the columns can be clicked on in order to sort the entire table using that column, click again and it changes the order from ascending to descending. Clicking on a row will cause the RFI observations in the map to "flash" for several seconds so that the user can visualize it. Alternatively, clicking on an RFI observation in the map will highlight the relevant row in the table. The green button to the upper-left of the table can be used to save the data in the table as a "comma-separated values", or CSV, file that can be imported into various database programs. This enables using the data in ways not provided for in the visualization tool.

Help

Use the "Help" button at the top right in order to bring up a new page showing this help document.