Find Delay Between Correlated Signals

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Three sensors at different locations measure vibrations caused by a car as it crosses a bridge. The signals they produce arrive at the analysis station at different times. The sample rate is 11,025 Hz. Use theSignal Analyzerapp to determine the delays between the signals.

Load the signals into the MATLAB® Workspace. The name of each signal includes the number of the sensor that took it.

loadsensorData

Open the app. Drag all three signals from theWorkspace Browserto the Signal table. Add time information. Select the three signals in the Signal table and click theTime Valuesbutton on the分析仪tab. Select theSample Rate and Start Timeoption and enter the sample rate of 11,025 Hz. For more information, seeEdit Sample Rate and Other Time Information. Plot the first two signals in separate displays.

The signal froms2arrives earlier than the signal froms1.

The signals share a common time axis. Link their time spans by selecting each display and selectingLink Timeon theDisplaytab. To estimate the delay between the signals, pan them horizontally and line up a salient feature to the end of the time axis. From theTimetab, read the time from the lower limit of the time-axis. Choose a region where the signal-to-noise ratio is high, such as the signal maximum toward the end of each signal. In the signal froms2, that feature occurs about 0.197 second after the clock starts. Similarly, the signal froms1has that feature about 0.229 second after the start. Therefore, the delay is approximately 0.032 second.

You can also use data cursors to find a delay. Press the space bar to reset the view. Clear the bottom display and then plots3. On theDisplaytab, clickData Cursorsand selectTwo. Place a cursor on the maximum of each signal. You can read the lag of approximately 0.014 second betweens1ands3直接from the app.

You can get similar results with thefinddelayandxcorrfunctions.

Find Delay Between Correlated Signals

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