How To Use The Scope Filter Channel

Recently, a new channel was added to the Oscilloscope Tool. Now in addition to the two original oscilloscope channels, the basic and custom math channels and reference channels, you can also add a filter channel.

To demonstrate this channel, first I’ll start with a custom waveform. Open theWaveform Generatorand select the custom mode. Clicknew, to add a new custom channel.

We’ll start with the default sine wave. Make sure the default settings match mine, and then clickgenerate.

Next we’ll need to add a higher frequency component. Open theAlter tab并确保+添加selected. ClickAlter with.

Here, the same default sine wave will populate. Change the Cycles selection from 1 to10.这将添加一个正弦波component with 10 times the frequency. You should see the waveform that I have below in the Custom window. Clickokayto add it to theWaveform Generator.

Make sure that your custom waveform that was just created is selected, then and clickRun. Connect the Waveform Generator to Oscilloscope Channel 1.

Open theOscilloscope Tooland clickrun. You may need to change some of the channel and time settings to see the portion of the waveform shown above. Make sure all your settings match those in the above image.

Next we’ll add a new filter channel.

ClickAdd Channel,and selectFilterunder the Math heading.

You should see a Math Channel with Filter settings added below Channel 1 and 2.

Click on theFilter Buttonto open the settings. Filter gives the option of a Chebychev, Butterworth, or Custom filter. When Chebychev or Butterworth are selected, you can choose between 2nd and 16th order, Low pass, High pass, Band pass, or Bandstop, and one or two cutoff frequencies. When Chebychev is selected, you can also choose the Eplison parameter. When Custom is selected, the filter is determined from the table of coefficients.

For this example, I’ll need aChebyshevlow passfilter of order16.I’ll choose a cutoff frequency of5kHz,since its above the lower frequency of 1kHz, but lower than the higher frequency component.

Clickcloseand you should see the lower frequency component of the custom waveform, a 1kHz sine wave.

If you have any questions about the filter channel or the update toWaveForms, comment below or post on theDigilent Forum. If you want to learn more about filters, check outReal Analogchapters 7, 8, and 11, which cover filters.