After the beacon coordinates have been configured, the Beacon Configuration program will automatically enter the tracking mode, which displays the listener's position (represented by a red square) in real time. The user may now use the listener device as a virtual mouse in free space to draw various objects such as polylines, circles and rectangles. The drawing interface is based on a ``pen up'' and ``pen down'' model, much behaves much like an old-fashioned plotter. For example, click on the check box for Line once will anchor the first end point in the line. Click on the check box again (after moving the listener to a different position) will anchor an intermediate point on the polyline. The second end point of the polyline is anchored when the user clicks on ``PenUp''.
To erase a drawn object, move the mouse to high-light the object to be erased and click on the right mouse button. Clicking on the ``EraseAll'' button would wipe all the drawn objects from the screen.
This drawing program can be used to capture the general shape and position of various objects (e.g. furniture) in the environment by outlining the objects with the listener. If the listener can be set steadily for a length of time during the outlining process, one can produce an amazingly accurate capture of the environment!
Due to the sliding window distance filtering algorithm, there is a lag in tracking the listener's position. Depending on the beacon range, the level of contention, the noise in the distance readings, and various other factors, this lag may increase up to the size of the sliding window, which has default value of 4 seconds.
The ``Aggressive'' option bypasses the sliding window and enables CricketDaemon to compute position estimates based on the very last distance sample measured from each beacon. The tracking latency is reduced at the cost of increased errors from the occasional incorrect distance measurement
When enabled, the ``Streamer'' option draws the trail of the Cricket listener during tracking mode.
Finally, there is an option to display the distance annunus, which graphically represents the distance measured by the listener with respect to each beacon. The thickness of the annunus represents one half standard deviation of the measured distance. Thus, the intersection of the annuni graphically depicts the approximate position of the listener. The annunus display offer some intuition about how the position estimation works in real time.