plotting frequency response of sweep input

[popcorn]

I am trying to find the frequency response of an input at a given frequency and then plot the frequency response for the entire frequency sweep. How can I do it in S&V assistant?

[Ima U]

Hi popcorn,

1. Open Sound and Vibration Assistant
2. Add Step
• Click "Add Step" >> "Acquire Signal" >> "Analog Input" >> "Voltage"
• Choose device and channel analog input voltage
3. Create Signal
• Right click under DAQmx Acquire step and select "Create Signal" >> "Create Signal"
4. Create Frequency Response step
• Right click under Create Signal Step and select "Analysis" >> "Frequency-Domain Measurements" >> "Frequency Response"
• Choose the two signals you would like to use
5. Create the Frequency Sweep step
• Right click under the Frequency Response step and select "Execution Control" >> "Sweep"
• Add all other steps (DAQmx Acquire, Create signal and Frequency response) into the Sweep step box

Take a look at the project that I have attached as an example.  I hope this helps!

[popcorn]

If I drag the magnitude response (output of frequency response) to dataview, the whole range of frequency response is plotted. The snapshot of the plot is as attached. I wanted to have a plot of the frequency response at the instant frequency only. How can i do it?

[dsb@NI]

It sounds like you want to measure the frequency response with a frequency sweep.

Please refer to the following SignalExpress example:
...\Program Files\National Instruments\SignalExpress\Examples\Loops\Frequency Sweep (Simple Formula).seproj

This example generates the sweep and measures the frequency response of a filter. You can create a project that acquires an input channel and uses the Tone Extraction step to measure the amplitude of the tone with the highest amplitude. You can use the Formula step to compute the gain of the channel relative to a constant reference or relative to a reference channel. If you also want to measure the phase response, you will need to acquire a reference channel.

In the future, we can probably provide more specific guidance if you attach your project and document your test system and the measurement you want to make.