Data Acquisition Tab

The Data Acquisition tool is one of the powerful time domain measurement tools as introduced in Unique Set of Analysis Tools and is available on all MFIA instruments . This tab used to be named Software Trigger tab in previous versions of the LabOne software.

Features

  • Time-domain and frequency domain display for all continuously streamed data

  • Capture and color scale display of imaging data

  • Frame averaging and pixel interpolation

  • Automatic trigger level determination

  • Display of multiple traces

  • Adjustable record history

  • Mathematical toolkit for signal analysis

Description

The Data Acquisition tab features display and recording of shot-wise and imaging data sets upon a trigger event. Whenever the tab is closed or an additional one of the same type is needed, clicking the following icon will open a new instance of the tab.

Table 1. App icon and short description
Control/Tool Option/Range Description

DAQ

btn mnu daq um

Provides complex trigger functionality on all continuously streamed data samples and time domain display.

The Data Acquisition tab (see Figure 1) is divided into a display section on the left and a configuration section on the right. The configuration section is further divided into a number of sub-tabs.

functional swtrig
Figure 1. LabOne UI: Data Acquisition tab

The Data Acquisition tool brings the trigger functionality of a scope with FFT capability to the demodulator signals and other streamed data. The user can choose between a variety of different trigger and display options in the time and frequency domain.

Use the Control sub-tab to configure which signals are measured, both in time and in frequency domain. Measurement signals can be added to the Vertical Axis Groups section as described in Vertical Axis Groups. There is one vertical axis group for each the time domain and the frequency domain data.

The trigger condition is configured in the Settings sub-tab. Among the selection of Trigger Types provided here, Edge and Pulse are applicable to analog trigger sources such as demodulator data, auxiliary voltages, or oscillator frequencies. The trigger time resolution is enhanced above the sampling rate of the analog data by using interpolation. Instead of manually setting a Trigger Level, you can click on btn uielements find um to have LabOne find a value by analyzing the data stream. In case of noisy trigger sources, both the Bandwidth and the Hysteresis setting can help preventing false trigger events. The Bandwidth setting provides a configurable low-pass filter applied to the trigger source. When enabling this function, be sure to choose a sufficiently high bandwidth to resolve the signal feature that should be triggered upon, i.e., the signal edge or pulse. The Bandwidth setting does not affect the recorded data.

For trigger sources with a slowly varying offset, the Tracking Edge and Tracking Pulse Trigger Types provide continuous adjustment of the Level and Hysteresis. In Tracking mode, the Bandwidth setting plays a different role than for the Edge and Pulse trigger types. Here, the Bandwidth should be chosen sufficiently low to filter out all fast features and only let pass the slow offset. The Trigger Types HW Trigger and Digital are used for TTL signals on the Trigger Inputs or on the DIO lines. Using the Bits and Bit Mask setting, complex multi-bit trigger conditions on the DIO lines can be defined. The timing resolution for digital triggers is given by the demodulator sample rate because the state of the DIO line is transferred together with demodulator data.

The Horizontal section of the Settings sub-tab contains the settings for shot Duration and Delay (negative delays correspond to pre-trigger time). Also minimum and maximum pulse width for the Pulse and Tracking Pulse trigger types are defined here.

The Grid sub-tab provides imaging functionality to capture and display two-dimensional data sets organized in frames consisting of rows and columns. By default, the number of rows is 1, which means the Data Acquisition tool operates similar to a scope. With a Rows setting larger than 1, every newly captured shot of data is assigned to a row until the number of rows is reached and the frame is complete. After completion of a full frame, the new data either replace the old or averaging is performed, according to the selected Operation and Repetitions setting. On the horizontal axis, the Duration of a shot is divided into a number of samples specified with the Columns setting. The Mode settings provides the functionality for post-processing of the streamed data for interpolation, resampling, and alignment with the trigger event. This is particularly helpful when capturing data from several sources, e.g. demodulators and PID controllers. As illustrated in Figure 2, in such situation the streamed data don’t lie on the same temporal grid by default. This can be changed by setting Mode to Linear or Nearest. In these modes, the streams from several sources will be upsampled to match the sampling rate and temporal grid of the fastest data stream. This means data processing after saving becomes more convenient, however note that the actual streamed data rate is not increased, and the data don’t gain in time resolution. A two-dimensional color scale image of the data can be enabled and controlled in the Display section. The display features configurable scaling, range, and color scale.

With enabled grid mode, the data of a completed frame after averaging appear as a list entry in the History sub-tab. See History List for more details on how data in the history list can be managed and stored.

functional swtrig grid resampling
Figure 2. Samples from different sources configured with different rates: demodulator 1 at 2N kSa/s, demodulator 2 at N kSa/s and PID Error 1 at M kSa/s (N not divisible by M). Although each stream consists of equidistantly spaced samples in time, the sample timestamps from different streams are not necessarily aligned due to the different sampling rates

Functional Elements

Table 2. DAQ tab: Control sub-tab
Control/Tool Option/Range Description

Run/Stop

btn uielements runstop um

Start and stop the Data Acquisition tool

Single

btn uielements single um

Run the Data Acquisition tool once (record Count trigger events)

Force

btn uielements force um

Forces a single trigger event.

Triggered

grey/green

When green, indicates that new trigger shots are being captured and displayed in the plot area.

Table 3. DAQ tab: Settings sub-tab
Control/Tool Option/Range Description

Trigger Signal

btn uielements tree um

Source signal for trigger condition. Navigate through the tree view that appears and click on the required signal.

Trigger Type

Select the type of trigger to use. Selectable options depend on the selected trigger signal.

Continuous

Continuous triggering.

Edge

Analog edge triggering based on high and low level. Hysteresis on the levels and low-pass filtering can be used to reduce the risk of wrong trigger for noisy trigger signals.

Digital

Digital triggering on the 32-bit DIO lines. The bit value defines the trigger condition. The bit mask controls the bits that are used for trigger evaluation. When using a Positive Edge trigger setting, a trigger event occurs as soon as the equality (DIO Value)AND(Bit Mask) = (Bits)AND(Bit Mask) is fulfilled (and was not previously fulfilled). In order to trigger on DIO0 set bit value to 1 and bit mask to 1; to trigger on DIO1 set bit value to 2 and bit mask to 2.

Pulse

Triggers if a pulse on an analog signal is within the min and max pulse width. Pulses can be defined as either low to high then high to low (positive), the reverse (negative) or both.

Tracking Edge

Edge triggering with automatic adjustment of trigger levels to compensate for drifts. The tracking speed is controlled by the bandwidth of the low-pass filter. For this filter noise rejection can only be achieved by level hysteresis.

HW Trigger

Trigger on one of the four trigger inputs. Ensure that the trigger level and the trigger coupling is correctly adjusted. The trigger input state can be monitored on the plotter.

Tracking Pulse

Pulse triggering with automatic adjustment of trigger levels to compensate for drifts. The tracking speed is controlled by the bandwidth of the low-pass filter. For this filter noise rejection can only be achieved by level hysteresis.

Pulse Type

Positive/Negative/Both

Select between negative, positive or both pulse forms in the signal to trigger on.

Trigger Edge

Positive/Negative/Both

Triggers when the trigger input signal is crossing the trigger level from either high to low, low to high or both. This field is only displayed for trigger type Edge, Tracking Edge and Event Count.

Bits

0 to 2^32-1

Specify the value of the DIO to trigger on. All specified bits have to be set in order to trigger. This field is only displayed for trigger type Digital.

Bit Mask

0 to 2^32-1

Specify a bit mask for the DIO trigger value. The trigger value is bits AND bit mask (bitwise). This field is only displayed for trigger type Digital.

Level

full signal range

Specify the trigger level value.

Find

btn uielements find um

Automatically find the trigger level based on the current signal.

Hysteresis

full signal range

The hysteresis is important to trigger on the correct edge in the presence of noise. The hysteresis is applied below the trigger level for positive trigger edge selection. It is applied above for negative trigger edge selection, and on both sides for triggering on both edges.

Count

integer number

Number of trigger events to record (in Single mode)

Trigger progress

0% to 100%

The percentage of triggers already acquired (in Single mode)

Bandwidth (Hz)

0 to 0.5 * Sampling Rate

Bandwidth of the low-pass filter applied to the trigger signal. For edge and pulse trigger use a bandwidth larger than the signal sampling rate divided by 20 to keep the phase delay. For tracking filter use a bandwidth smaller than signal sampling frequency divided by 100 to just track slow signal components like drifts.

Enable

ON / OFF

Enable low-pass filtering of the trigger signal.

Hold Off Time (s)

positive numeric value

Hold off time before the trigger is rearmed. A hold off time smaller than the duration will lead to overlapping trigger frames.

Hold Off Count

integer value

Number of skipped triggers until the next trigger is recorded again.

Delay (s)

-Duration to Duration

Time delay of trigger frame position (left side) relative to the trigger edge. For delays smaller than 0, trigger edge inside trigger frame (pre trigger). For delays greater than 0, trigger edge before trigger frame (post trigger)

Refresh Rate

100 mHz to 10 Hz

Set the maximum refresh rate for plot updates. The actual refresh rate depends on other factors such as the hold-off time and duration.

Pulse Min (s)

0 to Duration

Minimum pulse width to trigger on.

Pulse Max (s)

0 to Duration

Maximum pulse width to trigger on.

Window

Rectangular

Seven different FFT windows to choose from. Depending on the application it makes a huge difference which of the provided window function is used. Please check the literature to find out the best trade off for your needs.

Hann

Hamming

Blackman Harris

Exponential (ring-down)

Cosine (ring-down)

Cosine squared (ring-down)

Absolute Frequency

ON / OFF

Shifts x-axis labeling to show the demodulation frequency in the center as opposed to 0 Hz, when turned off.

Spectral Density

ON / OFF

Calculate and show the spectral density. If power is enabled the power spectral density value is calculated. The spectral density is used to analyze noise.

Table 4. DAQ tab: Grid sub-tab
Control/Tool Option/Range Description

Mode

Select resampling method for two-dimensional data recording.

Off

Two-dimensional data recording is disabled.

Nearest

Resampling is performed using substitution by closest data point.

Linear

Resampling is performed using linear interpolation.

Exact (on-grid)

Adjust the duration so that the grid distance matches the maximal sampling rate of the selected signals. This allows for on-grid sampling of measurement data. If a signal uses lower sampling rate it will be up-sampled by linear interpolation.

On Grid Sampling

Green or yellow

When green, indicates that all the captured data is aligned to the grid. When yellow, indicates that some data is not aligned to the grid and is interpolated. This can happen when one or more data sources have different sampling rates, or when a sampling rate changes.

Operation

Select row update method.

Replace

New row replaces old row.

Average

The data for each row is averaged over a number of repetitions.

Std

The data for each row is the standard deviation over a number of repetitions.

Columns

numeric value

Number of columns. The data along the horizontal axis are resampled to a number of samples defined by this setting.

Duration

up to 1000 s

Recording length for each triggered data set. In exact sampling mode the duration is a read-only field. The duration is then defined by the maximal sampling rate and column size.

Rows

numeric value

Number of rows

Scan Direction

Select the scan direction and mode

Forward

Scan direction from left to right

Reverse

Scan direction from right to left

Bidirectional

Alternate scanning in both directions

Repetitions

numeric value

Number of repetitions used for averaging

Row-wise repetition

ON / OFF

Enable row-wise repetition. With row-wise repetition, each row is calculated from successive repetitions before starting the next row. With grid-wise repetition, the entire grid is calculated with each repetition.

Waterfall

ON / OFF

Enable to show the 2D plot in waterfall mode. It will always update the last line.

Overwrite

ON / OFF

Enable to overwrite the grid in continuous mode. History will not be collected. A history element will only be created when the analysis is stopped.

Plot Type

Select the plot type.

None

No plot displayed.

2D

Display defined number of grid rows as one 2D plot.

Row

Display only the trace of index defined in the Active Row field.

2D + Row

Display 2D and row plots.

Active Row

integer value

Set the row index to be displayed in the Row plot.

Track Active Row

ON / OFF

If enabled, the active row marker will track with the last recorded row. The active row control field is read-only if enabled.

Palette

Viridis

Select the colormap for the current plot.

Inferno

Balance

Turbo

Grey

Solar

Colorscale

ON / OFF

Enable/disable the colorscale bar display in the 2D plot.

Mapping

Mapping of colorscale.

Lin

Enable linear mapping.

Log

Enable logarithmic mapping.

dB

Enable logarithmic mapping in dB.

Scaling

Full Scale/Manual/Auto

Scaling of colorscale.

Clamp To Color

ON / OFF

When enabled, grid values that are outside of defined Min or Max region are painted with Min or Max color equivalents. When disabled, Grid values that are outside of defined Min or Max values are left transparent.

Start

numeric value

Lower limit of colorscale.

Only visible for manual scaling.

Stop

numeric value

Upper limit of colorscale.

Only visible for manual scaling.

Table 5. DAQ tab: History sub-tab
Control/Tool Option/Range Description

History

History

Each entry in the list corresponds to a single trace in the history. The number of traces displayed in the plot is limited to 20. Use the toggle buttons to hide or show individual traces. Use the color picker to change the color of a trace in the plot. Double click on a list entry to edit its name.

Length

integer value

Maximum number of records in the history. The number of entries displayed in the list is limited to the 100 most recent ones.

Clear All

btn uielements clearall um

Remove all records from the history list.

Clear

btn uielements clear um

Remove selected records from the history list.

Load file

Load data from a file into the history. Loading does not change the data type and range displayed in the plot, this has to be adapted manually if data is not shown.

Name

Enter a name which is used as a folder name to save the history into. An additional three digit counter is added to the folder name to identify consecutive saves into the same folder name.

Auto Save

Activate autosaving. When activated, any measurements already in the history are saved. Each subsequent measurement is then also saved. The autosave directory is identified by the text "autosave" in the name, e.g. "sweep_autosave_001". If autosave is active during continuous running of the module, each successive measurement is saved to the same directory. For single shot operation, a new directory is created containing all measurements in the history. Depending on the file format, the measurements are either appended to the same file, or saved in individual files. For HDF5 and ZView formats, measurements are appended to the same file. For MATLAB and SXM formats, each measurement is saved in a separate file.

File Format

Select the file format in which to save the data.

Save

btn uielements save um

Save the traces in the history to a file accessible in the File Manager tab. The file contains the signals in the Vertical Axis Groups of the Control sub-tab. The data that is saved depends on the selection from the pull-down list. Save All: All traces are saved. Save Sel: The selected traces are saved.