With so many companies in Silicon Valley eagerly pursuing a revolutionary data compression algorithm that could break the boundaries on storage space and source-coding, the voluntary consensus is to have a set of standards for all the companies utilizing data compression in their services. Source-coding for data compression is used in data systems in areas including reduction of transmission channel bandwidth, reduction of buffering and storage requirement, and reduction of data-transmission time at a given rate. It is compression done at the source of data to reduce redundancy, and decrease data size.
The Consultative Committee for Space Data Systems (CCSDS) is an organization established by a plethora of companies pursuing source coding. They have created a voluntary Recommended Standard to which companies are not bound, but are encouraged to follow.
The document created has been titled the CCSDS Recommended Standard for Lossless Data Compression and can be found as ISO 15887:2013 Space data and information transfer systems – lossless data compression on the ANSI webstore. While lossless source coding technique preserves all data and manages to remove redundancy from the data source, a lossy source coding method removes some of the data while removing redundancy. Original data cannot be fully restored. The document details guidelines on only the lossless method, which is applicable to a range of digital data including imaging and non-imaging. Source coding is described rather than channel coding, which would increase the size of the data by adding codewords that detect errors in the code.
Errors that can occur when using the source coding algorithm described and their solutions are also addressed in the document. For example, ISO 15887 recommends using telemetry channel coding or packetized telemetry, both described within the document.
For those familiar with Rice’s adaptive coding technique, recommendations are provided on the required variables used by the technique, along with comparisons to the other options for codeword sequencing. Variables the document states that Rice’s adaptive coding technique requires are block size (J), resolution (n), and the ID bit sequence of the collected code option.
Space data compression may seem an intimidating subject to many, even for those attempting to conquer it in their industry. The CCSDS document ISO 15887 attempts to simplify the process and provide a consensus standard for companies utilizing source coding for data compression. By decoding the packets of compressed data, the original data can be reconstructed while taking up less storage space. Data compression potential continues to progress, with the industry thriving in its pursuit – thus creating more need for standardization of methodologies.
