This packetofdata (usually about four kilobytes of code) is then embedded within the file, and a digital watermark is inserted into the newly created space left behind by the compression process.
In recent weeks Dr Smith and Dr Sample, working with Scott Southwood, another researcher at the University of Washington, have built a weather sensor that measures temperature and light levels and sends a packetofdata every five seconds by radio.
But it can deliver that smaller packetofdata with a shorter turn around time (two hours instead of as much as two weeks) and the entry cost is low enough that scientists who have shied away from DNA sequencing could buy their own PGM.