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| title | Glossary |
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This glossary defines key terms used throughout the WFDB specification, software, and associated documentation.
A general term that refers to a set of open standards, file formats, and software for representing, storing, and analyzing physiologic waveform and annotation data. Originally developed at MIT by George B. Moody in 1989.
The formal definition of the WFDB file formats: headers (.hea), signal files (.dat), and annotation files (.atr, .ann, etc.).
The specification describes how physiologic data and event annotations should be encoded, independent of any software implementation.
The collection of software tools, libraries, and applications that read, write, visualize, and process WFDB-formatted data.
This includes the original WFDB C library, Python packages, MATLAB toolboxes, and command-line utilities.
A signal (e.g., ECG) for which only variations in level are significant. Baseline (DC offset) is removed prior to digitization.
A device that converts continuous analog signals into discrete digital samples.
The number of significant bits per sample produced by the ADC, determining the granularity of the digital representation.
The digital output value corresponding to a 0-volt input. For unipolar ADCs, this is typically 1024.
The native unit of a digital sample before conversion to physical units. Values are in integers corresponding to ADC output.
A legacy annotation format originating from the American Heart Association (AHA) database standard.
It uses fixed-length annotation records (16 bytes each).
A marker associated with a specific sample, identifying events like heartbeats, arrhythmias, or comments.
A binary file (e.g., .atr, .ann) containing annotations linked to a signal record.
A value corresponding to the counter (e.g., tape counter) at sample 0, used for mapping counter ticks to time.
The date at which the record begins, specified in DD/MM/YYYY format.
The time of day when the recording starts, in HH:MM:SS format (24-hour clock).
A single data stream within a record, such as an ECG lead or arterial blood pressure waveform. Typically a record will include multiple channels.
The number of counter ticks per second, used for records originally stored on analog media.
A signal after analog-to-digital conversion, consisting of discrete numerical samples.
A set of simultaneous samples from all signals at a single time point.
A scaling factor to convert from ADUs (digital units) to physical measurement units like millivolts or mmHg.
A text file (.hea) that defines the metadata for a WFDB record, including signal specifications.
A record composed of multiple segments, allowing variable signal types or gaps in recording.
The reconstructed analog signal after scaling the digital samples by gain and baseline correction.
A named collection of files (header, signal, annotation) representing a single physiologic recording.
The first non-comment line of a header file, summarizing basic properties like number of signals and sampling rate.
The number of samples acquired per second, specified in Hertz (Hz).
A binary file (e.g., .dat) containing waveform samples for one or more channels.
A line in the header file that describes a specific signal’s properties, including format, gain, units, and file name.
The physical measurement units (e.g., millivolts, mmHg) associated with a signal, specified in the header file.
This site is intended to serve as a quick reference when working with WFDB-formatted data.
For full technical specifications, please refer to the WFDB Programmer's Guide and WFDB Applications Guide.