Step 6: Create a new signal using Calculated Channels

Overview

Imagine you want to define new signals that simplify downstream analysis, capture domain-specific logic, or highlight important patterns not directly available from raw data. This is where Calculated Channels come in.

Calculated Channels allow you to derive new signals from one or more existing telemetry Channels using expressions. For example, you can compute the difference between max_air_temp(C) and min_air_temp(C) to track the daily air temperature swing. These derived signals make it easier to capture trends, express engineering insight, and support downstream diagnostics or visualization.

Create a Calculated Channel

Now, let’s create a Calculated Channel that computes the difference between max_air_temp(C) and min_air_temp(C) to capture the daily air temperature swing and see how it appears alongside the original telemetry in Explore.

1. In Sift, click .
2. Click the Calculated Channels tab.
3. Click New Calculated Channel.
4. In the Calculated Channel name box, enter:

   fl_air_temp_swing(C)

   Replace fl with your own initials.

5. In the Asset name box, select your Asset (for example, fl_mars_env_monitoring_station).
6. In the Input Channels list, select the following Channels:
   • max_air_temp(C)
   • min_air_temp(C)
7. In the Enter an expression box, enter:

   $1 - $2

8. Click Save.

Plot Calculated Channel

Now that you’ve created a Calculated Channel, it’s time to view it alongside the original telemetry. In this step, you’ll plot the new signal with its source Channels to observe how the derived values compare over time.

1. In Sift, click .
2. Click the Runs tab.
3. In the Run name or description box, enter:

   fl_env_telemetry_two_thousand_twenty_one

   Replace fl with your own initials.

4. Click your Run from the search results to open it.
5. Click Explore 2.
6. In the Channels tab, click the following Channels:
   1. max_air_temp(C)
   2. min_air_temp(C)
7. Click the Calculated Channels tab.
8. In the Calculated Channels tab, click fl_air_temp_swing(C).

   Replace fl with your own initials.

The Calculated Channel offers a fresh way to understand the data by combining existing signals into something more meaningful. Instead of looking at individual temperature readings, you can now see how much the air temperature changes from day to night. This helps you spot patterns or unusual behavior that might not be obvious when looking at the raw values alone.