Where digital data is costly or subject to federal law (space, seismic or medical imaging), importance of the data may lead to exclusive use of lossless encoding. We present a pattern-tracking algorithm for lossless encoding, complete with a file header. This algorithm is based upon the expectation that data contain patterns that re-occur with varying amplitudes. This algorithm is compared to standard lossless coding algorithms using 24 data sets from four signal applications. Compression ratios were 1.6 to 2.7. The pattern-tracking algorithm performed best on certain data sets, while competing algorithms performed best on other data sets.