Using the Spectrum Analyzer (Under Construction)

1.1

Plug in your Test & Measurement Device, then start WaveForms and make sure your device is connected.

If no device is connected to the host computer when WaveForms launches, the Device Manager will launch automatically.

Make sure that the device is plugged in and turned on, at which point it will appear in the Device Manager's device list (1.). Click on the device in the list (“DEMO” devices are also listed, which allow the user to use WaveForms and create projects without a physical device) to select it, then click the Select button (2.) to close the Device Manager.

Note: The Device Manager can be reopened by clicking on the “Connected Device” button in the bottom right corner of the screen (3.), or by selecting “Device Manager” from the “Settings” menu at the top of the screen.

1.2

Once the Welcome page loads, in the Instrument Panel at the left side of the window, click on the Spectrum button to open the Spectrum instrument.

1.3

Once the Spectrum instrument opens, the window contains the plot plane, the Control Bar above the plot plane, and the Configuration Panel to the right of the plot plane.

2.1 Hardware Setup

In order to measure a signal with the Spectrum instrument, there must first be a signal to measure. To this end, step 2.1 of this guide describes setting up a simple loopback circuit that connects the <test & measurement device>'s Waveform Generator and Oscilloscope pins.

Connect the <test & measurement device>'s scope channel 1 pin (orange wire) to the device's wavegen channel 1 output pin (yellow wire). For devices that use differential input channels, such as the Analog Discovery Studio with MTE cables, make sure to connect the scope channel 1 negative pin (orange wire with white stripes) to the ground pin associated with wavegen channel 1 (black wire).

With the loopback circuit set up, a signal must now be applied to the analog output pins. WaveForms' Wavegen instrument will be used to accomplish this.

From the Spectrum instrument, opened in step 1.2, return to WaveForms' Welcome page by clicking on its tab at the top of the screen. In the Welcome tab, open the Wavegen instrument, then click the “Run” button in the control bar near the top of the window to begin outputting a signal. With default settings, a 1V amplitude (2V peak-to-peak) 1kHz sine wave is applied to the wavegen channel 1 output pin. Change the frequency to 500kHz by selecting the Frequency parameter drop down menu or by typing into the text field.

For more detail on how to use the Wavegen instrument, please see the Using the Waveform Generator guide.

Return to the Spectrum instrument by clicking on its tab in the bar at the top of the screen.

2.3 Begin Capturing Data

Click the Run button () button in the control bar near the top of the window to begin capturing data on the analog input channels. Captured data will appear in the plot pane as a set of colored lines. The yellow line (labeled 1. in the image to the right) corresponds to the signal captured on analog input channel 1. The blue line (2.) corresponds to the signal captured on analog input channel 2.

Since analog input channel 2 was left “floating” (not connected) while making connections in step 2.1, it can be disabled by clicking the checkbox in the “Channel 2” box (3.) in the configuration panel at the right side of the window.

2.4 Plot Pane Axes

By default, the plot vertical axis units are decibel volts (dBV) from -200dBV to 0dBV and the horizontal axis is frequency from 0MHz to 1MHz. To change these values, use the Control Bar located above the plot plane or the Configuration Panel located to the right of the plot plane which are discussed in subsequent sections. With the Spectrum tool running, the plot should show a large “spike” at 0.5MHz (the 500kHz sine wave from the WaveGen 1 channel) peaking close to 0dBV with all other frequencies between -80dBV and -120dBV (electronic noise).

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2.5 Plot Plane Cursors

To take a quick measurement of the period and frequency of the sine wave, click the “Quick Measure: Vertical” button at the top right side of the plot pane. Move the cursor over the plot pane, and observe the values displayed. If the values change too quickly to make out, the capturing of data can be stopped by clicking on the “Stop” button () in the control bar near the top of the window. To remove this cursor, deselect the “Quick Measure: Vertical” button. Normal and delta cursors are available by clicking on the “Add Cursor” button located in the bottom left corner of the plot plane. Click and hold the cursor icon to drag it to a point of measurement in the plot plane. To change the cursor's position, delta, reference, and/or color parameters or to delete the cursor, click the arrow on the right side of the cursor icon and update these parameters as necessary.

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3.1 Control Bar

The Control Bar is located above the plot plane. Located on the left side of the Control Bar, the Single and Run control buttons will start measurements with either a single acquisition or a continuous acquisition, respectively. By default, the Control Bar displays to the right of the control buttons Frequency Range, Start Frequency, Stop Frequency and Resolution parameters set to Auto, 0Hz, 1MHz, and 244.141Hz respectively. To change these values from default (except Resolution), click on the drop down arrow or type in the text field.

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3.2 Additional Control Bar Parameters

For further controls, click the wide, downward arrow button on the right side of the Control Bar. This will bring down an additional row of parameters: scale, center frequency, frequency span, and number of samples. To change these parameters (except Samples), click on the drop down arrow or type in the text field. Click the gear icon to change the acquisition algorithm and enable control of the Resolution and Samples parameters.

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3.3 Configuration Panel

To the right of the plot plane is the Configuration Panel. At the top is the Magnitude plot configuration window. Here, the vertical axis units and range can be changed by clicking the drop down menu arrow of the Units, Top, and Bottom parameters, respectively.

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3.4 Channel Options and Add Trace Buttons

Below the Magnitude plot configuration window are the Channel Options and Add Trace buttons, which are opened by clicking the drop down menu arrow to the right of the button name. Channel Options allows the user to apply an offset voltage, adjust the range of the measurement signal, attenuate the measurement signal, and sample mode by selecting the drop down arrows for Offset, Range, Attenuation, and Sample Mode, respectively. The Channel Options menu also provides additional Trigger configuration parameters.

The Add Trace button located below the Channel Options button will generate another measurement trace window.

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3.5 Trace Windows

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