Control tab (Source dialog)

Selecting Source > Control opens the Source dialog Control tab. The Source Control tab provides all the controls and parameters required for VSA integrated control and operation of an external source.

You must first select a Source Configuration to enable the Source Control tab controls and parameters.

Connect - Connects (or Disconnects) the Source Configuration. All parameters are disabled until you connect to the selected source configuration.

Source Channel - Some of the parameters in the tab are channelized, meaning each channel may have a different assigned value.

Selecting All populates channelized parameter values when all of the component carriers have the same assigned value. If one or more component carriers have differing values, "multiple values" will appear in the parameter's field.

Channelized parameters will display a drop-down icon to the right of the parameter. The color of the icon indicates the following:
- Channelized parameter - All channels currently have the same assigned value for this parameter.
- Channelized parameter - Some channels currently have different values for this parameter.
You can also use the drop-down menu to change the tab's selected Source Channel (or all channels), which functions the same way as Source Channel.

Selecting an individual Source Channel will populate channelized parameters in the Control tab with the assigned values for just that channel.

If you are connected to a source that supports virtual signals, you can configure up to eight virtual signal generators per channel in the Download Waveform to Source area. See Supported Sources.

RF Frequency - Specifies the source carrier frequency for the selected Source Channel.

Frequency Step - Specifies the incremental frequency step size for the keyboard arrow keys and mouse wheel. This setting applies to all channels.

Amplitude - Specifies the source signal output power level for the selected Source Channel.

RF on - When selected (true), sets the source "RF Radio Frequency: A generic term for radio-based technologies, operating between the Low Frequency range (30k Hz) and the Extra High Frequency range (300 GHz). ON" parameter to ON, which turns on the source's RF output for the selected Source Channel.

Modulation on - When selected (true), sets the source "Modulation ON" parameter to ON, which applies modulation to the carrier signal for the selected Source Channel.

Download Waveform to Source ("All" Source Channels selected)

Waveform Adjustment - Selects how the waveform will be adjusted when the waveform does not meet the source’s waveform length requirements. The available Waveform Adjustment choices depend on the model of source and its installed options.

Hover your mouse over the Waveform Adjustment drop-down box to see a pop up that displays the source length requirements, which includes the minimum waveform length and length quantum number.

Extend with Zeros - The ARB waveform is extended with zeros to meet the minimum waveform length (in points) and the waveform length quantum (length in points must be a multiple of the quantum) requirements. Note: this option does not ensure periodicity when the source is in Continuous playback.

VSA versions prior to VSA 2024 Update 2.0 used truncation to trim the waveform to meet the source's length quantum requirement (multiple of some number of samples). Truncation is no longer used because Extend with Zeros satisfies source requirements with no risk of data loss.
Ensure Periodicity - The ARB waveform is repeated, if necessary, to meet the minimum waveform length (in points) and the waveform length quantum (length in points must be a multiple of the quantum) requirements. This will ensure periodicity of the waveform in Continuous playback. For sources that support event/trigger out, there will be at least a trigger at the beginning of the repeated waveform, but not necessarily at each repetition. Note that for sources that don't support hardware-based repetition, this can increase the amount of data transferred to the source (affecting download speed and memory usage on the source).
Ensure Periodicity and Event Out - Same as Ensure Periodicity except that, for sources that support event/trigger out, there will be a trigger at each repetition of the waveform (if repetition needed).

Last Downloaded File - Displays the name of the last waveform file that was downloaded to the source. The Last Downloaded File field is updated whenever a new waveform file is downloaded to the source.

Download Current Recording - Opens the Select dialog that is used to configure and download the current VSA measurement recording for ARB Source playback. See See "Using Source Download and Recording".

Select dialog options:

At measurement span

Selected  - The recording data in the current measurement span is downloaded instead of the entire recording span.

Cleared  - The recording data is downloaded at the span when the recording was made.

Between playback start/stop times

Selected  - Downloads only the data between the playback start and stop times. See Specifying the Start/Stop region.

Playback "Start Time" and "Stop Time", see Playback Tab (Recording).

Cleared- Downloads the entire recording.

When the recording is downloaded into the source, the center frequency is specified by the RF Frequency parameter (Source > Control tab), not the current VSA measurement center.

Download File - Use Download File to select and download a VSA recorded signal file (VSA MATLAB ".mat" format) to an ARB Source for signal playback. See Source Signal Playback.

Each channel of a multi-channel waveform will be mapped to a different source channel if the mapping is 1:1. If a single-channel waveform is downloaded and multiple channels are enabled, the same waveform will be played on all enabled channels.

The order of the channels in the Channels tab is the same way channels will be ordered in the downloaded waveform.

Waveform parameters automatically set on download - When checked, Sample Rate and RMS Power are set using values from the file or recording. When unchecked, the current values of Sample Rate and RMS Power are retained through the waveform download.

Download Waveform to Source (individual Source Channel selected)

Hover your mouse over the Waveform Adjustment drop-down box to see a pop up that displays the source length requirements, which includes the minimum waveform length and length quantum number.

Extend with Zeros - The ARB waveform is extended with zeros to meet the minimum waveform length (in points) and the waveform length quantum (length in points must be a multiple of the quantum) requirements. Note: this option does not ensure periodicity when the source is in Continuous playback.

VSA versions prior to VSA 2024 Update 2.0 used truncation to trim the waveform to meet the source's length quantum requirement (multiple of some number of samples). Truncation is no longer used because Extend with Zeros satisfies source requirements with no risk of data loss.
Ensure Periodicity - The ARB waveform is repeated, if necessary, to meet the minimum waveform length (in points) and the waveform length quantum (length in points must be a multiple of the quantum) requirements. This will ensure periodicity of the waveform in Continuous playback. For sources that support event/trigger out, there will be at least a trigger at the beginning of the repeated waveform, but not necessarily at each repetition. Note that for sources that don't support hardware-based repetition, this can increase the amount of data transferred to the source (affecting download speed and memory usage on the source).
Ensure Periodicity and Event Out - Same as Ensure Periodicity except that, for sources that support event/trigger out, there will be a trigger at each repetition of the waveform (if repetition needed).

Remaining Sample Rate - All virtual signals in a source channel share the same available sample rate (for example, the M9494C VXG's available sample rate is 3.0 GHz Gigahertz: A frequency measurement which equals one billion hertz.). Each enabled virtual signal consumes a portion of the available sample rate. Remaining Sample Rate is the amount of the available sample rate that is not used by enabled virtual signals.

Virtual Signal Table (only available when connected to a supported source)

Virtual Signal	Enable	Sample Rate	RMS Power	Frequency Offset	Attenuation	Download Recording	Download File	Last Downloaded Waveform
Index of the virtual signal (up to eight per channel)	Enables the virtual signal. A virtual signal is enabled after its waveform is downloaded, unless the virtual signal’s sample rate exceeds Remaining Sample Rate. In this case, the waveform downloads but the virtual signal remains disabled. See Sample Rate for more information.	Sample rate (Hz) for the virtual signal. Each enabled virtual signal consumes a portion of the available sample rate. A virtual signal with a downloaded waveform cannot be enabled if its sample rate exceeds the remaining sample rate. The Sample Rate entry of a virtual signal is highlighted in the table with a yellow border if its Enable checkbox is disabled because its sample rate value exceeds Remaining Sample Rate.	RMS Power is a unitless ratio that sets the relationship between Total RMS Power (set by the source channel Amplitude property) and Peak Envelope Power, where PeakEnvelopePower (dBm deciBels referenced to a milliWatt: dB relative to 1 milliwatt dissipated in the nominal input impedance of the analyzer) = TotalRMSPower (dBm) – ∑ [20 * log10(RMSPower)], with the sum of values from enabled virtual signals. By default, RMS Power is set when a waveform is downloaded using a value from the file or current recording data. A M9494C VXG Vector Signal Generator sets the power of each virtual signal so that the sum is Total RMS Power. However, the signal generator has a maximum peak power. The RMS Power value of each virtual signal may call for a Peak Envelope Power that exceeds what the signal generator can produce. This is indicated as an error condition in the signal generator user interface.	Frequency Offset (Hz) for the virtual signal. The offset is the distance in frequency (Hz) from the channel’s RF center frequency to the center of the modulation bandwidth.	Attenuation (dB) allows scaling a virtual signal down in amplitude. The dynamic range is not adjusted (optimized) when this value is adjusted. This virtual signal’s power relationship with other virtual signals, including noise, is not adjusted when this value is changed. The amount of attenuation applied is relative to the maximum of the Attenuation values of all enabled virtual signals. This property has no effect when only one virtual signal is enabled.	Opens a dialog to configure and download the current VSA measurement recording to the virtual signal generator.	Selects and downloads a VSA recorded signal file (VSA MATLAB ".mat" format) to the virtual signal generator.	Displays the name of the last waveform file that was downloaded to the source. The full path name is displayed by the tooltip displayed when hovering the mouse over the text box. When a current recording is downloaded, <recording> is displayed.

Virtual Signal

Enable

Sample Rate

RMS Power

Frequency Offset

Attenuation

Download Recording

Download File

Last Downloaded Waveform

Index of the virtual signal (up to eight per channel)

Enables the virtual signal. A virtual signal is enabled after its waveform is downloaded, unless the virtual signal’s sample rate exceeds Remaining Sample Rate. In this case, the waveform downloads but the virtual signal remains disabled. See Sample Rate for more information.

Sample rate (Hz) for the virtual signal. Each enabled virtual signal consumes a portion of the available sample rate.

A virtual signal with a downloaded waveform cannot be enabled if its sample rate exceeds the remaining sample rate. The Sample Rate entry of a virtual signal is highlighted in the table with a yellow border if its Enable checkbox is disabled because its sample rate value exceeds Remaining Sample Rate.

RMS Power is a unitless ratio that sets the relationship between Total RMS Power (set by the source channel Amplitude property) and Peak Envelope Power, where PeakEnvelopePower (dBm deciBels referenced to a milliWatt: dB relative to 1 milliwatt dissipated in the nominal input impedance of the analyzer) = TotalRMSPower (dBm) – ∑ [20 * log10(RMSPower)], with the sum of values from enabled virtual signals. By default, RMS Power is set when a waveform is downloaded using a value from the file or current recording data. A M9494C VXG Vector Signal Generator sets the power of each virtual signal so that the sum is Total RMS Power. However, the signal generator has a maximum peak power. The RMS Power value of each virtual signal may call for a Peak Envelope Power that exceeds what the signal generator can produce. This is indicated as an error condition in the signal generator user interface.

Frequency Offset (Hz) for the virtual signal. The offset is the distance in frequency (Hz) from the channel’s RF center frequency to the center of the modulation bandwidth.

Attenuation (dB) allows scaling a virtual signal down in amplitude. The dynamic range is not adjusted (optimized) when this value is adjusted. This virtual signal’s power relationship with other virtual signals, including noise, is not adjusted when this value is changed. The amount of attenuation applied is relative to the maximum of the Attenuation values of all enabled virtual signals. This property has no effect when only one virtual signal is enabled.

Opens a dialog to configure and download the current VSA measurement recording to the virtual signal generator.

Selects and downloads a VSA recorded signal file (VSA MATLAB ".mat" format) to the virtual signal generator.

Displays the name of the last waveform file that was downloaded to the source. The full path name is displayed by the tooltip displayed when hovering the mouse over the text box. When a current recording is downloaded, <recording> is displayed.

Waveform Trigger

Waveform Trigger parameters are used to control triggering of downloaded waveforms.

The VSA software always uses Continuous trigger mode with sources that support Continuous and Single trigger modes.

Trigger controls are not displayed in the GUI when VSA does not support triggering for the source, or the source does not have trigger capabilities. See the Source Requirements topic for sources that support triggering.

Trigger Type

Immediate – (Default) Waveform play starts as soon as a waveform is loaded and enabled.

Software– Waveform play starts when the Software Trigger button is clicked.

Global Trigger – Waveform play starts when the Global Trigger source trigger is asserted. Global Trigger starts repeatable, phase coherent waveform play. See the Source Requirements topic for sources that support Global Trigger.

Global Trigger Type

Immediate – (Default) Phase coherent waveform playback starts as soon as a waveform is loaded and enabled.

Software – Phase coherent waveform play starts when the Software Trigger button is clicked.

When Trigger Type is Immediate, a virtual signal’s markers are output as soon as the virtual signal is enabled. Setting Trigger Type to Software can be used to disable markers until all virtual signals are configured. Output of markers starts when Software Trigger is executed.

Trigger Action – Selects the action that is initiated by the trigger.

Run – Waveform play starts when trigger is received. Subsequent triggers are ignored.

Reset and Run – Waveform play starts when trigger is received. Subsequent trigger while waveform is playing will reset play to the start of the waveform. This mode is not supported for GlobalTrigger trigger type.

Software Trigger – Initiates a software trigger when the Trigger Type is set to Software.

Using Source Download and Recording

Using "Current" and "From File"

There are two Download Recording options: Download Current Recording and Download File:

Max Download File Size: The data block size to be downloaded to a source must be < 250 Mpts.

You will receive an ERROR message when the download a recording data size exceeds the source maximum memory size, see Reducing Download Recording Size.

Using "Download File..."

The Download File... option is used to browse, recall, and load a saved signal recording file for download and playback. This option allows you to save a measurement signal recording and recall it at a later time for detailed signal analysis. This feature also allows you to share a common signal recording file with multiple co-workers running the VSA software.

Using "Download Current Recording"

The Download Current Recording option opens the Select dialog and is used to configure and download the current VSA measurement signal recording for playback. You do not need to download the entire signal recording for playback. For example, you may only want to do further signal analysis on a specific region (time interval) of the measurement recording.

Specifying the Start/Stop region

There are two methods for defining the recording download region (time interval) within the current measurement recording:

You can use the Recording Playback "Start Time" and "Stop Time" parameters to specify the recording download playback region.
You can open and use the recording Player (Window > Player) to specify the download playback region. The graphical user interface makes it easy to visually identify the playback region of interest within the measurement recording.

Reducing Download Recording File Size

When you are downloading using the Download Current Recording option, zooming in on a subset of the recording span and selecting “At measurement span” will reduce both the sample rate and the amount of data downloaded (by the ratio of the current measurement span to the span of the recording). Selecting “Between playback start/stop times” will reduce the amount of data downloaded but will not affect the sample rate.