296 Keysight InfiniiVision 2000 X-Series Oscilloscopes User's Guide22 ReferenceCSV and ASCII XY file structureIn CSV or ASCII XY format the Length control selects the number of points persegment. All segments are contained in the CSV file or in each ASCII XY data file.For example: If the Length control is set to 1000 points, there will be 1000 points(rows in the spreadsheet) per segment. When saving all segments there are threeheader rows, so the data for the first segment starts at row 4. The secondsegment's data starts at row 1004. The time column shows the time since thetrigger on the first segment. The top row shows the selected number of points persegment.BIN files are a more efficient data transfer format than CSV or ASCII XY. Use thisfile format for fastest data transfer.Minimum and Maximum Values in CSV FilesIf you are running a Minimum or Maximum measurement, the minimum andmaximum values shown in the measurement display may not appear in the CSVfile.Explanation: When the oscilloscope's sample rate is 4 GSa/s, a sample will be taken every250 ps. If the horizontal scale is set to 10 us/div, there will be 100 us of datadisplayed (because there are ten divisions across the screen). To find the totalnumber of samples the oscilloscope will take:100 us x 4 GSa/s = 400K samplesThe oscilloscope is required to display those 400K samples using 640 pixelcolumns. The oscilloscope will decimate the 400K samples to 640 pixel columns,and this decimation keeps track of the min and max values of all the points thatare represented by any given column. Those min and max values will be displayedin that screen column.A similar process is used to reduce the acquired data to produce a record usablefor various analysis needs such as measurements and CSV data. This analysisrecord (or measurement record) is much larger than 640 and may in fact containup to 65536 points. Still, once the # of acquired points > 65536, some form ofdecimation is required. The decimator used to produce a CSV record is configuredto provide a best-estimate of all the samples that each point in the recordrepresents. Therefore, the min and max values may not appear in the CSV file.
