You may find that an existing database of digitally recorded signals may be useful for your studies. PhysioNet, at,, offers free on-line access to over 40 such databases with thousands of recordings ranging in length from a few seconds to several days. These include all or most of the MIT-BIH Arrhythmia Database, the European ST-T Database, the MIT-BIH Polysomnographic Database, the MGH/MF Waveform Database, and the Long-Term ST Database (which are also available on CD-ROMs from their creators), and many other databases available only via PhysioNet. WAVE can read these databases directly from PhysioNet without downloading them first (the WFDB library, which handles reading and writing data for WAVE , contains HTTP client code that permits applications such as WAVE to read input with equal ease from local disks or remote web servers). This is an excellent way to explore PhysioBank (PhysioNet's collection of signal databases).

George B. Moody (