# Function Example: Using Interpolate to Change the Time Interval of a Channel

For many analysis tools inside and outside of FlowWorks, it is required that data be logged every so often, in a fixed time interval that is consistent across all data being used in the study. For example, If your flow data was logged every 15-minutes but you need values for every 5-minutes, it can be a daunting task to use Excel to break-up the data. Instead, you can use FACE's Interpolate function to create a fixed interval time series by linearly interpolating between the values of the source Channel. As described in this example, with Interpolate you can create virtual flow data that is in smaller time intervals, based off the source Channel's flow data.

#### The Process for Using Interpolate in a Channel is Twofold:

1. Start by creating a Calculated Channel. Once complete, you will need to proceed to step 2 (which is discussed in this topic). The image below shows Channel setup for this example:

2. Configure FACE with the Interpolate Function. this will copy in data from the original Channel and apply the function to the data.

Note: These instructions are a continuation from the topic, "Creating a Calculated Channel". From step one, it is assumed that you are back at the Configure Sites Page, after having completed setup of a new Calculated Channel.

To configure FACE for data interpolation:

1. Starting from the Configure Sites page, locate the "Rainfall 5-min" Calculated Channel you just created. First find the Site that the Channel resides in, then choose the Channel.
2. Click View Calculated Channel. This will direct you to the respective page, where summarizing information on the Calculated Channel is displayed.
3. Click Create Calculation. This will take you to the page where you will configure the calculation. This page has three distinct sections - the following steps take you through each part, beginning from the top of the page.
4. Provide a Calculation Name and Description (both are optional).
5. For Calculation Type, select Interpolate. The bottom of the page will update with drop-down lists to allow you to define the source channel and interval length.
6. Select the Source Channel, that contains the raw 15-minute data. Use the first drop down list to select the Site that the Channel resides in, then select the Channel.
7. Select "5 min" for Interval Length.
8. Click Save.

Now, you can use the Interpolated 5-min Flow Channel in many of FlowWorks' analysis tools, including I & I. You can also use it in lieu of the Flow (gpm) channel for graphing, reporting, alarming, etc. That was painless, right?