Visualization of packet radio message traffic. Data source: Automatic Packet Reporting System (APRS)

Throughout the visualization, each message is colored as function of whether the corresponding callsign is selected in one or both of two callsign lists. There are four color combinations: disjunctive red (selected in the first list) and yellow (selected in the second list), conjunctive orange (selected in both lists), and negative white (selected in neither list). The idea here is to support a variety of boolean queries regarding particular combinations of callsigns in terms of their national origin or stationary/vehicular/satellite location.

A main map show the location of message events. Movable portals in the map correspond to four independent inset maps, allowing the user to zoom in on multiple particular locations of interest. A timeseries window show independent timeseries for each callsign, below a combined timeseries designed to show all possible boolean combinations of the two selected callsign sets.

Mousing over the timeseries induces a snake-swallowing-the-egg gaussian sizing effect in message location paths in the main map and insets, as a way to scrub back and forth through time. A signal detail window shows messages with a fixed range centered at the time at the mouse pointer. A draggable portal over the time series optionally filters the main map and insets to only show message events within a given time range, independent of the mouseover effect.

The screenshot shown above shows an exploration of radio traffic shortly after 9/11. Around midnight of 9/21, messages from the VA3DVR-14 call-sign suggest unusual vehicular behavior (possibly deliveries by a shipping truck) between Grand Rapids and Lansing prior to crossing the border into Canada (Portal 4). Other messages involved stationary call-signs near major cities (Portals 1 and 3).

Visualization (1.4 MB)
Video Tour (9.1 MB)

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