For echosounder data products only. Currently used by the ASL Acoustic Profiler Time Series data products.
Ensemble Period
This option will cause the search to perform the standard box-car average resampling on the data. 'Boxes' of time are defined based on the ensemble period, e.g. starting every 15 minutes on the 15s, with the time stamp given as the center of the 'box'. Acoustic pings that occur within that box are averaged range or bin-wise, and the summary statistics, such as nPingsPerEnsemble are updated. This process is often called 'ping averaging'. The process uses log scale averaging (back out the dB scale to pressure, average, compute the dB scale again), and weighted averages if we're averaging raw data that is already an ensemble or ping average.
The default value is no averaging, meaning the data is not altered. Some echosounders are configured to do ping averaging during acquisition, so the data you request with this option could already be averaged. To determine if the echosounder is averaging data as it is acquiring, check the device details page (e.g. 23296); data products will document this as well: see the comment field in the plots or the Config structure in mat files. Available ensemble periods are 1, 10, 15 and 60 minutes.
Calibration
This option will apply the calibration to the data, when the calibration co-efficients are available. The calibration calculation and co-efficients are supplied by the manufacturer. See the device details page (additional attributes tab) to see the values. These values are also provided in the mat file Config structure.
The default value is to apply calibration when available. The alternative option will provide the raw data (normally in raw counts, which are proportional to the received acoustic pressure).