YSI Data Scout - Manual (Page 25)

3.5.2 METHOD TEST TAB
There are four possible Scan Methods available. The selected method utilizes the Scan Interval that set in the Time tab. Each Scan
Method interprets this interval in a unique way.
Figure 3.41
ƒ Linear - This results in logging data at a constant interval (scan interval) for the entire test (Figure 3.41).
ƒ Linear Averaged - This method averages x data points into one logged measurement. For example, a test which had a scan
interval of 10 minutes would acquire 6 measurements per hour. If the Scan Method was Linear Averaged and the Averages
were set to 6 then only one measurement would be logged in the test record every hour. Each of those logged measurements
would be the average of the 6 discrete measurements spaced at 10 minute intervals.
ƒ Logarithmic - This method begins recording data at the shortest interval possible, increasing the interval after each
measurement on a logarithmic curve until the interval equals the scan interval defined on the Time tab. The Time tab’s scan
interval is maintained until the test ends.
ƒ Event Based - This method takes a measurement at the scan interval defined on the Time tab but does not log the
measurement unless one of two conditions is met. A measurement is logged every x scans as defined by the Default # Scans in
the Method tab (Figure 3.42). A measurement will also be logged if the difference between the previous measurement and the
current measurement is equal to or greater than the Delta value for either the pressure (level) or temperature measurement
(depending on what is selected). For example, a test is configured to log data for 3 months with a scan interval of 5 minutes
(12 times an hour). The goal is to log a measurement once an hour if there is no change in water level and to log every
measurement if the water level changes 0.5 feet between the 5 minute intervals. Therefore, Delta is set to 0.2 (PSI), pressure is
selected and the Default # Scans is set to 12. Note, the units for Delta Pressure are always in PSI and the units for Delta
Temperature are always in degrees centigrade. Any pressure or temperature change value between 0.0 and 999.9 may be
specified in the Delta text box.
Figure 3.42
YSI Incorporated Data Scout 25