Differences
This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
test-and-measurement:guides:waveforms-spectrum-analyzer [2022/09/12 15:56] – changed forum.digilentinc.com to forum.digilent.com Jeffrey | test-and-measurement:guides:waveforms-spectrum-analyzer [2024/02/29 14:21] (current) – [Using the Spectrum Analyzer] replaced image Fausto Soares | ||
---|---|---|---|
Line 1: | Line 1: | ||
+ | ======Using the Spectrum Analyzer====== | ||
+ | ~~TechArticle~~ | ||
+ | |||
+ | {{test-and-measurement/ | ||
+ | |||
+ | ===== Introduction ===== | ||
+ | Spectrum Analyzers are used to view captured analog signals in the frequency domain. This guide explains the use of WaveForms' | ||
+ | |||
+ | --> What Does a Spectrum Analyzer Do? # | ||
+ | |||
+ | You are most likely familiar with looking at signals on an oscilloscope image, which plots the magnitude of the signal on the y-axis (vertical) and the time on the x-axis (horizontal). With these plots, the change in the strength of the signal over time can clearly be seen. This should be no surprise. | ||
+ | |||
+ | {{ : | ||
+ | < | ||
+ | |||
+ | Another way to visualize a plot is in the frequency domain. The y-axis still represents magnitude, but frequencies are plotted on the x-axis instead of time. Now we can see how the magnitude of a signal changes with the frequency of that signal, regardless of when in time we find ourselves interacting with that signal. | ||
+ | |||
+ | {{ : | ||
+ | < | ||
+ | |||
+ | The Spectrum Analyzer simply reads every single frequency within the data acquisition window. It starts at the lowest frequency, reads the signal strength at that frequency, displays the value on the graph, then moves up just a little bit to the next frequency. It does this many times a second, so all you see is a constantly fluctuating image, with spikes where you have a stronger signal at that frequency. The number of samples it takes per second, the resolution of the data read, the span of the acquisition window, etc., are all variables that can be adjusted in real time so that you can get the clearest data. | ||
+ | |||
+ | <-- | ||
+ | |||
+ | ---- | ||
+ | ===== Prerequisites ===== | ||
+ | * A Digilent Test & Measurement Device with Analog Input and Output Channels: | ||
+ | * [[test-and-measurement: | ||
+ | * [[test-and-measurement: | ||
+ | * [[test-and-measurement: | ||
+ | * [[test-and-measurement: | ||
+ | * [[test-and-measurement: | ||
+ | * [[test-and-measurement: | ||
+ | * [[test-and-measurement: | ||
+ | * A Computer with WaveForms Software Installed | ||
+ | |||
+ | ---- | ||
+ | ===== Guide ===== | ||
+ | ==== 1. Opening the Spectrum Analyzer==== | ||
+ | |||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | === 1.1 === | ||
+ | Plug in the Test & Measurement Device, then start WaveForms and make sure the device is connected. | ||
+ | |||
+ | If no device is connected to the host computer when WaveForms launches, the **Device Manager** will be launched. Make sure that the device is plugged in and turned on, at which point it will appear in the Device Manager' | ||
+ | |||
+ | **Note:** //" | ||
+ | |||
+ | **Note:** //The Device Manager can be opened by clicking on the " | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{ reference: | ||
+ | </ | ||
+ | </ | ||
+ | ---- | ||
+ | <WRAP group>< | ||
+ | === 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 Analyzer// instrument. | ||
+ | </ | ||
+ | {{ reference: | ||
+ | </ | ||
+ | ---- | ||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | === 1.3 === | ||
+ | Once the //Spectrum Analyzer// instrument opens, the window contains the plot pane, the Control Bar (1) above the Plot Pane (2), and the Configuration Panel (3) to the right of the plot pane. | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{ reference: | ||
+ | </ | ||
+ | </ | ||
+ | |||
+ | ---- | ||
+ | ==== 2. Using the Spectrum Analyzer==== | ||
+ | |||
+ | //This section walks through setting up the //Spectrum Analyzer// instrument to analyze a signal in the frequency domain.// | ||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | === 2.1 Hardware Setup === | ||
+ | In order to measure a signal with the //Spectrum Analyzer// instrument, there must first be a signal to measure. To this end, a simple loopback circuit will be set up to connects the Test & Measurement Device' | ||
+ | |||
+ | Connect the Test and Measurement device' | ||
+ | |||
+ | When using a device with MTE cables, Wavegen Channel 1 is a yellow wire and Oscilloscope Channel 1 is an orange wire. | ||
+ | |||
+ | For devices that use differential input channels, such as the Analog Discovery Studio with MTE cables, make sure to connect the Oscilloscope Channel 1 negative pin (orange wire with white stripes) to the ground pin associated with Wavegen Channel 1 (black wire). | ||
+ | |||
+ | **Note:** //The analog input channels can be used with BNC Cables. For more information, | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{ : | ||
+ | </ | ||
+ | </ | ||
+ | ---- | ||
+ | <WRAP group> <WRAP column half> | ||
+ | When using a device with BNC cables, make sure to set the attenuation of the oscilloscope probes in the Channel Options menu. | ||
+ | </ | ||
+ | {{ reference: | ||
+ | </ | ||
+ | ---- | ||
+ | === 2.2 Input Signal === | ||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | With the loopback circuit set up, a signal must now be applied to the analog output pins. WaveForms' | ||
+ | |||
+ | From the //Spectrum Analyzer// instrument, opened in [[# | ||
+ | |||
+ | For more detail on how to use the //Wavegen// instrument, please see the [[test-and-measurement: | ||
+ | |||
+ | Return to the //Spectrum Analyzer// instrument by clicking on its tab in the bar at the top of the screen. | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{ : | ||
+ | </ | ||
+ | </ | ||
+ | ---- | ||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | === 2.3 Begin Capturing Data === | ||
+ | Click the Run button ({{: | ||
+ | |||
+ | Note that for devices with more than two analog input channels, each channel will be displayed. For the Analog Discovery Pro (ADP3450/ | ||
+ | |||
+ | Since other analog input channels were left " | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{ : | ||
+ | </ | ||
+ | </ | ||
+ | ---- | ||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | === 2.4 Plot Pane Axes === | ||
+ | By default, the plot vertical axis units are decibel volts (dBṼ) and the horizontal axis is frequency in MHz. 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 as discussed in [[# | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{ : | ||
+ | </ | ||
+ | </ | ||
+ | ---- | ||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | === 2.5 Quick Measure Cursors === | ||
+ | To take a quick measurement of the period and frequency of the sine wave, click the Quick Measure: Vertical icon ({{: | ||
+ | |||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{ : | ||
+ | </ | ||
+ | </ | ||
+ | ---- | ||
+ | ==== Note: Using Multiple Instruments ==== | ||
+ | The //Spectrum Analyzer// instrument can be used with other WaveForms instruments. Using multiple instruments at the same time is helpful in a wide variety of situations. One example would be to use the //Waveform Generator// to stimulate a circuit under test, the //Power Supplies// to provide power to the circuit, and the //Spectrum Analyzer// to record the response. More information on how instruments can be operated together can be found in the [[test-and-measurement: | ||
+ | |||
+ | It should be noted that the analog input channels cannot be shared by multiple instruments. When the //Spectrum Analyzer// is enabled, any other instruments using the analog input channels are disabled. Other instruments that use the analog input channels include the // | ||
+ | ---- | ||
+ | ====3. Spectrum Analyzer User Interface Overview==== | ||
+ | //This section describes the various controls present in the //Spectrum Analyzer// instrument.// | ||
+ | ---- | ||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | ===3.1 Control Bar=== | ||
+ | The Control Bar is located above the plot plane. The Single and Run control buttons, located on the left side of the Control Bar, will start measurements with either a single acquisition or a continuous acquisition, | ||
+ | |||
+ | Several fields, to the right of the control buttons, can be used to configure the //Spectrum Analyzer//. By default, the **Frequency Range**, **Start** frequency, and **Stop** frequency fields can be seen. These options also change the x-axis of the plot. | ||
+ | |||
+ | Additional configuration options can be found by clicking on the green down arrow ({{learn: | ||
+ | |||
+ | Clicking on the Gear button ({{learn: | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{: | ||
+ | </ | ||
+ | </ | ||
+ | ---- | ||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | ===3.2.1 Configuration Pane - Magnitude=== | ||
+ | To the right of the plot is the Configuration Pane. | ||
+ | |||
+ | In the Magnitude section of the Configuration Pane, the plot's vertical axis units and range can be changed by selecting a value out of the particular field' | ||
+ | |||
+ | /* Gear button has no relevant options? */ | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{ : | ||
+ | </ | ||
+ | </ | ||
+ | ---- | ||
+ | <WRAP group>< | ||
+ | ===3.2.2 Configuration Pane - Range=== | ||
+ | The **Range** field, below the Magnitude configuration options, can be used to specify the voltage range for the analog input channels. Selecting larger ranges may reduce the sample resolution. | ||
+ | </ | ||
+ | {{ : | ||
+ | </ | ||
+ | ---- | ||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | ===3.2.3 Configuration Pane - Channel Options=== | ||
+ | Clicking on the " | ||
+ | |||
+ | The //Trigger// section of the Channel Options menu allows the user to specify a trigger event, around which samples will be captured and analyzed in the plot pane. By default, the instrument is configured to capture and analyze data whenever the signal applied to Oscilloscope Channel 1 rises above 0V. | ||
+ | /* Cross Triggering */ | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | /*{{ : | ||
+ | {{ reference: | ||
+ | </ | ||
+ | </ | ||
+ | ---- | ||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | ===3.2.4 Configuration Pane - Traces=== | ||
+ | Additional Traces can be added to the //Spectrum Analyzer// instrument by clicking on the "Add Trace" button ({{learn: | ||
+ | |||
+ | Below the Channel Options and Add Trace buttons are the Trace configurations. | ||
+ | |||
+ | By default, Trace 1 and Trace 2 correspond to analog input Channel 1 and analog input Channel 2, respectively. To change the Trace' | ||
+ | |||
+ | The **Type** drop-down is used to select how and when the data is updated, including various kinds of averaging schemes. By default the trace is updated whenever new data is captured. | ||
+ | |||
+ | The Gear icon in the top right of the Trace window can be used further configure the Trace, with color, name, label, and windowing technique options. To remove a Trace, click the red X to the right of the Gear icon. | ||
+ | |||
+ | For more information on Trace configuration, | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{ : | ||
+ | </ | ||
+ | </ | ||
+ | ---- | ||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | === 3.3 Plot Pane === | ||
+ | The Plot pane displays the spectrogram. The horizontal axis of the plot represents the frequencies of measured components. The vertical axis represents the ratio between the input signal' | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{ : | ||
+ | </ | ||
+ | </ | ||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | Capture status information can be found next to the channel select buttons, including a state string (Stop / Runnning / Busy). Information about the capture being displayed can be found to the right of the channel select buttons, including the sample rate, and timestamp for the latest capture (when the instrument is stopped). | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{ : | ||
+ | </ | ||
+ | </ | ||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | Another set of buttons can be found in the upper right corner of the plot pane. | ||
+ | |||
+ | Two "Quick Measure" | ||
+ | |||
+ | The Gear button next to these buttons can be used to change how the plot is displayed, including adding labels, changing the background between light and dark, and others. For more information on these options, refer to the WaveForms Help menu or the Reference Manual. | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{ : | ||
+ | </ | ||
+ | </ | ||
+ | <WRAP group> | ||
+ | <WRAP column half> | ||
+ | Normal and delta cursors are accessible by clicking on **X** and **Y** buttons/ | ||
+ | </ | ||
+ | <WRAP column half> | ||
+ | {{ : | ||
+ | </ | ||
+ | </ | ||
+ | |||
+ | ---- | ||
+ | <WRAP group>< | ||
+ | ===3.4 File Menu=== | ||
+ | The **File** menu can be used to save or load configurations of the //Spectrum Analyzer// instrument, export acquired data, or close the instrument. | ||
+ | |||
+ | Saving a project (with or without any acquisitions) allows the user to close WaveForms without losing the instrument configuration. In addition to this, projects can be shared with others to aid in group projects and guided learning. | ||
+ | |||
+ | Exporting data as an image produces a screenshot of the entire //Spectrum Analyzer// instrument. Alternatively, | ||
+ | </ | ||
+ | {{ : | ||
+ | </ | ||
+ | ---- | ||
+ | <WRAP group>< | ||
+ | ===3.5 Control Menu=== | ||
+ | Has the same functionality as the Run, Single and Stop buttons, also listing the hotkeys for these buttons. | ||
+ | </ | ||
+ | {{ : | ||
+ | </ | ||
+ | ---- | ||
+ | <WRAP group>< | ||
+ | ===3.6 View Menu=== | ||
+ | A wide variety of different panes can be added to the user interface using the **View** menu in the toolbar above the Single/ | ||
+ | * // | ||
+ | * //Time:// Used to view the captured signal in the time domain. | ||
+ | * // | ||
+ | * // | ||
+ | * //X Cursors:// Lists all frequency reference cursors that have been added to the plot in table form. (See [[# | ||
+ | * //Y Cursors:// Lists all amplitude reference cursors that have been added to the plot in table form. (See [[# | ||
+ | * // | ||
+ | * // | ||
+ | * //Notes:// Creates a text editor pane that can be used to document configuration choices, or whatever other information could be useful to remember. | ||
+ | </ | ||
+ | {{ learn: | ||
+ | </ | ||
+ | ---- | ||
+ | |||
+ | ==== Next Steps ==== | ||
+ | |||
+ | /* | ||
+ | If voltage values seen in the // | ||
+ | */ | ||
+ | |||
+ | For more guides on how to use the Digilent Test & Measurement Device, return to the device' | ||
+ | |||
+ | For more information on WaveForms visit the [[software: | ||
+ | |||
+ | For technical support, please visit the [[https:// |