What are common errors in EDF files?
Datablocks larger than 61440 bytes (problem for some viewers). Non-standard ascii characters (byte values 127-255) in the header. Not specifying the number of datarecords. Note that ‘-1’ can only be used before or during the recording. After the completion of a recording, the actual number of datarecords is known and should be specified. Inaccurate signal labels (like EEG abdomen for respiration effort signal). Incorrect transducer type (such as AgAgCl electrode for a rectal temperature probe signal). Incorrect physical dimensions (for instance uV for a respiration signal coming from a thermistor). Inaccurate or simply meaningless calibration values (i.e. physical and digital minimum/maximum), even in EDF files coming from very accurate equipment. Empty prefiltering fields, even when time constants or lowpass filters were applied to the signal in the file (suggestion: let the recording equipment automatically specify something like “Bandpass 0.1-75Hz” in the prefiltering field).
