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Simple distance tracker using baseband amplitude

Novelda recently released it's X2M200 respiration sensor which provides movement, distance, respiration frequency, and live breathing pattern tracking data. Through the X2M200s serial interface we can tap into this stream of high-level information and output raw baseband data (amplitude & phase) for further processing. The baseband down conversion simplifies the radar signal and makes the data easier to use in development.

The objective of this project is to create a simple tracker that measures the distance from the sensor to a moving object. Using the baseband raw data we add some simple signal processing and display the distance of the largest moving object on the computer screen. In addition to the X2M200 sensor we use an Atmel Xplained G55 board for development and debugging.

Distance Tracker setup

Figure 1: Distance tracker demo setup

In this demo we only want to detect and track moving objects and by adding a simple signal processing algorithm, described as an adaptive clutter map removal, we're able to discriminate reflections from static objects. This leaves us with a signal showing only the amplitude and distance to the moving object. See example in Figure 2.

Xethru baseband output plot

Figure 2: Baseband plot of a moving object

The top plot shows the raw baseband data with a strong static reflection close to the sensor. The second peak is a moving object at 1.2m distance from the sensor. After an adaptive clutter map removal the moving object is the only visible amplitude in the plot (second plot).

A simple detector using thresholds is implemented and the distance to the largest moving object displayed as shown in the screen shot below.

Xethru baseband output plot

Figure 3: Terminal window showing distance to moving object

Full video recording of the distance tracker demo is available below and Atmel studio project files are available for download in our community

Download Atmel Studio Project Files