Hi I'm Ngoc Do, Application Scientist at Spectradyne! In this video we will be going over peak filtering. This is a method to eliminate false positives in the data.
Let's see how we can do this with an example I'm showing here. This is a 150 nm particle standard measurement in a C400 cartridge. You can apply peak filtering to both stats files and combine files. To work with peak filters, go to the Peak Filtering tab. Here you can plot any parametric scatter plot by using the "Select Peak Parameter" drop-down list and click on the "View Scatter" button.
Let's take a look at what the transit time scatter plot would look like for this data. Select Transit Time from the drop-down list of parameters. This will plot the diameter on the y-axis and the transit time on the x-axis. Blue dot is an event that has been excluded by the applied peak filters. In this case, there are default peak filters that got applied automatically during a measurement run. The red dot is an event that was not excluded by default or any peak filters.
You can see the bead population well above the size limit for this type of cartridge, which is at 65 nm, and the population has a certain range for transit time. As mentioned, the default peak filters have been applied for this data. The default filters are appropriate choices for standard measurement conditions and samples, but they may not be appropriate in all cases. In those cases, you can apply your own filters as appropriate.
Notice the bloom you see spanning across broad transit times near the size limit for this cartridge type. This is the physical manifestation of the electrical noise false positives and this is what we need to eliminate from the data.
Saved filters for the chosen parameter are shown in the list on the left. Applied filters to the currently loaded files are highlighted in blue. Each parameter has its own list. Filter details can be viewed by selecting the chosen filter and click on the View button on the right frame.
To apply and remove existing filters as desired from files in the Currently Loaded file list, we can use the appropriate action buttons on the right. The "Active" button applies action to the highlighted file. The "All Loaded" applies action to all files in currently loaded window. Both of these will only apply to the selected parameter. The "Clear All From" option under "All Filters" will clear filters from all parameters.
Now we are going to clear all the default filters to apply our own custom filters. To create a new filter, use the "+" button at the bottom of the available filters list. Choose one of two options for the type of filter. The options are linear and polygon. Linear will apply a filter bound with constant value. Polygon filter will apply a 2D, user-defined polygonal boundaries. The dropdown list allow you to select from any of the four parameters.
So let's create a linear filter in transit time. We can specify a descriptive name for the filter. Let's say we want to create a transit time filter from 0 to 100. Enter the bounds with minimum of 0 and maximum of 100 and click Create button. The new filter will be added to the list and you would need to find and apply this filter to the appropriate data.
Plotting the updated transit time scatter plot, you can see now that due to the applied filter, anything above 100 microseconds in transit time have been excluded from the data as noted in blue. Anything below 100 microseconds are included, which are labeled in red.
Now let's create a polygon filter. First we need to remove the previously applied filter. We're going to go over to the "+" filter option and select polygon in transit time. Specify a descriptive name for this filter. For polygon filter, we have to click on "Set Boundary Graphically". The transit time scatter plot will be shown and from here you can create your own custom polygon shape. Remember the filter is inclusive so anything inside the polygon will be included and anything outside will be excluded from the data. Once you've created the desired shape, hit the Enter key on the keyboard. You can still modify and adjust the shape of the polygon afterwards if you'd like. Once you're happy with the polygon, click "Create" and apply the new filter to the data.
This concludes our session on peak filters. I hope you find it useful. Further details are available in the instrument Operation Manual and if you have questions, contact us at firstname.lastname@example.org.
More training videos are also available on our website. Thank you for your attention!