BSL PRO Software Guide - Biopac

294 Part EAppendix F - Hints for Working with Large FilesIt is not uncommon for large data files to be generated (on the order of several megabytes) through somecombination of (a) high-speed acquisitions, (b) long acquisitions, and (c) multi-channel acquisitions. You mayencounter system limitations (such as storage space limitations) and find such files difficult to work with and slow inloading to memory.The Biopac Student Lab PRO software stores the data in as compact a format as possible. Each analog sample takesup roughly two bytes of storage space and calculation channel samples take up roughly eight bytes of storage space.When a waveform (or a section of a waveform) is transformed (i.e., filtered or integrated) each data point takes uproughly eight bytes. As a result, file size can change drastically after transforming one or more waves.The following tips can help you get the most out of the Biopac Student Lab PRO when working with large data files.Use virtual memoryRemove waveformsSample slowlyDisplay preferencesStore to hard diskUse the Append modeStop plotting andchange the scaleSince the Biopac Student Lab PRO runs under Windows , most computers are able totake advantage of the virtual memory feature. While this is slower than conventionalmemory, it will at least make it possible to load some files that might otherwise beimpossible to load.Since each waveform adds to the total size of the file, try removing (or copying toanother file) some of the waveforms from a multi-channel file. This is especially true ifyou would like to perform transformations of some sort on at least one of the waves.Theoretical and methodological concerns will, to a large extent, dictate sampling rate.However, if you can reduce the sampling rate, choose to do so. You may also want toresample data after it has been collected by using the Transform > Resamplecommand (page 7217).Check the “Use all available memory” and the “Draft mode for compressed waves”options under the File > Preferences > General sub-menu. This should decrease thetime it takes to redraw waveforms and allow the software to access all availablememory for storage.Although slightly slower than storing to PC Memory (RAM), acquiring data directly toHard Disk allows you to recover data in the event of a power loss to the BiopacStudent Lab PRO. Furthermore, much larger data files can typically be stored directlyto Hard Disk than to PC Memory.The Append mode allows you to pause the acquisition for arbitrary periods. This canbe helpful when recording only a few key events that will occur randomly over a longperiod of time, since it will reduce unnecessary data.If the screen is taking a long time to redraw (because the data files are large), you canstop plotting and decrease the horizontal scale value before redrawing. To stopplotting, use the ESC key.Visit the online support center at www.biopac.com