Draft:Signal Metadata Format

Signal Metadata Format (SigMF) is a standardized representation for recorded digital signal time series, typically encompassing real or complex-valued radio signals, acoustic waves, antenna positions, or sensor voltages. The metadata is encapsulated in a JSON file with a  extension, usually situated alongside the binary data stored in a file with a   extension. Extensions enable the addition of hierarchical data to a complete dataset, a capture, or a specific region of the recording.

History
Before the standardization of SigMF, time series data representing radio signals were commonly stored in flat binary files with external descriptors. Occasionally, researchers used Hierarchical Data Format (HDF5) containers, but these containers lack specificity to any data type. The VITA Radio Transport Standard a.k.a. VITA 49  was at times employed for RF data storage, although it is primarily designed as a transport format for RF signals rather than for data storage purposes. Other proprietary formats were created by industry either to hold specific metadata or encode signals into proprietary containers.

In 2016 at the annual GNU Radio conference, a workshop focused on how a better open source container for RF signals could be constructed and maintained. In the following year the initial release of SigMF was created to provide a portable & annotated container for radio signals.