Step 9: Pack it up, run it and process data
Running the logger: there is no on switch, you just plug in the battery to the MEGA's power connector. At each power-on or reset, it will start a log with a new number. It can only hold up to 100 log names so be sure to clean off the memory card periodically. The memory card needs to be installed in a card reader for this, cannot read it through the USB cable.
Your data will be readable in Excel or a text editor (TextEdit, WordPad, etc) and should have a column of bytes along with the three different timestamps (milliseconds since logger started, seconds since 1/1/1970, and a more user friendly date-time format) The bytes contain radio packet information, signal strength info (if made available), the name of the radio sending the data, the serial number of the individual sensor that collected the data, and four bytes of sensor data that can be translated to temperature, voltage, pressure, flow rate, light intensity, etc.
What are the occasional lines of different length in the TelosB data? The character 7E sometimes shows up as a data byte about 1 in 256 chance, but it's a special character denoting end of line, so when the TelosB encounters this, it puts an escape character in front of the 7E, and changes the 7E to another character. So it has put 2 characters in place of 1. This escape character must also be escaped. It is possible to decode all this in a perl script. The Java application net.tinyos.tools.Listen does this step automatically when reading from the USB serial port.