There are two acquisition styles supported:
1.) On-Board Memory Mode
This mode takes snapshots of data during execution, but not all the real-time data is collected. The rate at which the snapshots are taken depends on the number of active display plots, the number of acquisition samples for each snapshot, the performance of the computer graphics subsystem and the processing power of the local CPU. Typical update rates are from 10 to 30 captures per second.
On-Board Memory mode can be used first to verify the acquisition setup prior to performing a streaming recording. This mode allows setup parameter adjustments while the acquisition is in progress so one does not have to start and stop operations before altering a parameter.
2.) Streaming Mode
In this mode, once the operation setup is complete the acquisition is armed and ready to be triggered. It is important to note that during Streaming modes of operation that the computer and storage subsystem must be configured and selected to sustain the required real-time data rates.
Streaming mode requires that the setup does not change during the acquisition process since there is no convenient mechanism to handle setup transitions during the streaming of data in real-time.
Acquisition captures are taken via One Shot or Continuous modes.
A One Shot acquisition acquires just one scan of data and displays the results in the available displays. After the One Shot operation is invoked the application awaits a trigger event. The trigger event is controlled through the Trigger selection on the Digitizer control tab. If a trigger event is not detected one may use the Force Trigger selection to force an acquisition and display update. The Stop or Abort selections can be used to return the acquisition to the idle state. The One Shot mode is only available when in the On-Board Memory mode of acquisition.
A Continuous operation runs until the user instructs the acquisition to cease through use of the Stop or the Abort controls. After the Continuous operation is invoked, the application awaits a trigger event. The trigger event is controlled through the Trigger selection on the Digitizer control tab. In On-Board Memory mode each acquisition awaits a trigger event before retrieving the digitizer data and displaying the results. For Streaming mode, the acquisition awaits a single trigger event before continually acquiring data.
Scope Cursors, Maximum Hold, and Averaging
Display windows allow the user to enable up to 2 cursors to navigate through the display and obtain measurements. Cursor control is available for Time Domain, Frequency Spectrum, and Spectrogram displays.
A bottom display plot information indicator strip identifies the values associated with placed Cursor 1 (C1), Cursor 2 (C2), and the value differences between the two cursors (C2-C1). Cursor Track Mode can be enabled to lock the position of the two placed cursors. When locked, the spacing between cursors remains constant as they are moved through the display of data.
During the course of zooming and panning in on a display window, it is possible for the cursor(s) to be placed outside of the visible area. An issued reset cursor position automatically resets the cursor positions to a default 1/3 and 2/3 locations relative to the current extent of the active display region.
In addition to scope cursors, a Maximum Hold plot can be selected to be shown on a Frequency Domain display as shown:
When enabled an additional waveform plot in red is shown on the graph to display the greatest value in magnitude since the Maximum Hold was enabled or reset. This feature is useful in capturing peak values in a waveform.
When selecting a reset of the Max Hold, the first plot update of the data forms the baseline data for the maximum hold values. Each additional plot value is compared against the last and the plot value of the greatest magnitude is retained.
An Averaging control enables or disables averaging a display before it is plotted. Not all displays support signal averaging. Those that support the feature will show the Averaging control button on the application menu bar enabled when the display window is selected.
Two Averaging mode options are available:
1.) Standard Averaging
User selects the number of scans of data that are to be averaged before display. The number of averages range from 1 to 64 in a power of 2 arrangement.
2.) Running Average
User selects the last number of scans of data to be averaged together for display. The last number of scans can be in the range from 1 to 64. As this is a running average, only the last indicated number of scans are kept and averaged. The averaging does not wait until an entire new set of number of scans are received, it merely uses the last number of scans obtained.
Time Domain Display
The Time Domain Display is the basic display for DsScope showing the acquired time domain data for a “snapshot” of samples.
If the Acquisition Style is set for On-Board Memory, the display(s) are updated for every acquisition that satisfies the trigger selected. For Streaming modes of operation, the display is updated based on the selections in the Streaming Mode Update Rates on the Data Plotting tab of the control interface.
Each active channel features a zero voltage indicator red reference line that can be selected and moved for each channel independently. There are several mechanisms to zoom in and out on the X-axis for the time per division display, and on the Y-axis for the volts per division display for each channel independently or all together.
Time Domain Display supports 2 cursors. A bottom plot indicator information strip identifies the position and voltage of the placed cursors, and the value differences between 2 placed cursor positions for measurements.
Frequency Domain Display
The Frequency Domain Display adds a Fast Fourier Transform (FFT) display to the application. When this selection is made the user is queried as to which channel to perform the FFT and display in a frequency domain plot. Multiple channels can be added to the single display for viewing.
The number of points used for the FFT in the frequency plot is dependent on the specified settings in the Data Plotting section that affects both the time domain data and the frequency plot data. Along with controlling the number of points in the Frequency Domain Plot one can select the FFT window type and the engineering units.
The Window Type selection determines the windowing applied to the data before the FFT is executed with available selections for Hanning and Hamming. The FFT Units controls the engineering units that are used to display the FFT results with available selections for:
|1 milliwatt (dBm)
The power ratio in decibels (dB) of the measured power referenced to one milliwatt (mW).
|Full Scale (dBfs)
The power ratio in decibels (dB) of the measured power referenced to the full scale channel setting.
|1 Volt (dBV)
The power ratio in decibels (dB) of the measured power referenced to a one volt measurement.
For any of the selected units, the calculation performed takes into account the input impedance selection for the channel displayed.
The FFT display data can be zoomed in and out and panned through via mouse control mechanisms. Enabling the option to Show Point Values will display the specific point values where hovered over the specific plot curve area.
In the upper left-hand corner of the display are the Display Scale Controls. These controls are used to specify the scale position at the top (Max) and bottom (Min) of the display as well as shifting the entire display (Offset) grid up or down in increments of 5 dB units.
The FFT display supports 2 cursors that can be independently connected to any active channel. Each cursor has its own rectangular shape showing the intersection of the cursor and the waveform with its color matching the color coding of the channel to which it is attached. A bottom plot indicator information strip identifies the position and voltage present at the placed cursor locations, and the value differences between 2 placed cursor positions. It is possible to leave a cursor pointing on a point of the curve that is not necessarily in a bin of the FFT. Points selected that are not in the center of a bin are interpolated.
The FFT display may have a maximum hold waveform placed that displays an additional red waveform “hold” showing the maximum power recorded during the plotting of frequency information. This maximum hold applies to all channels plotted in the display.
The Spectrogram plot is a dual-display window. In the top section of the display is a bitmap drawn to represent the magnitude of the power rendered as a color. The color gradient can be selected by the user to customize the rendering of the power magnitude. The lower section of the display shows the FFT output plot.
The spectrogram plot provides a mechanism to view a frequency over time. The FFT plot is the same as the standard Frequency Domain display with all the same navigation properties, same FFT settings for data plotting, same display scale controls, and same support for 2 cursors tracking and measurements.
FFT Display data can be zoomed in and out and panned through via mouse control mechanisms. When zooming in on the FFT portion of the display the spectrogram maintains the full bandwidth of the display and the color bitmap follows the zoomed range as well.
In DsScopeView, one may pause the display playback when they see a peak of interest in the displayed color bitmap. By double-clicking on the color bitmap one can have the time-domain display automatically repositioned to the data that caused the peak in the spectrogram. This is a useful feature when searching for pulsed signals.
Signal recording is supported through DsScope using the Streaming selection for the Acquisition Mode. Onboard Memory mode can be used first to verify the acquisition setup prior to performing a signal recording.
Onboard Memory mode allows setup parameter adjustments while the acquisition is in progress so one does not have to start and stop operations before altering a parameter.
Streaming mode requires that the setup does not change during the acquisition process since there is no convenient mechanism to handle setup transitions during the streaming of data.
Several parameters must be set prior to initiating a signal recording. The setup configuration is accessed through the Settings button in the Global Control section. The following table identifies typical settings that can be established.
The targeted duration of a recording operation can be specified by either total data file size or by elapsed time (hours, minutes, seconds) or a combination of both total file size and time. Signal recordings can also be manually controlled via the Start/Stop recording button selections.
|User Text Field
A general use text box that the user can enter up to 256 characters to describe the data acquisition conditions. This entry is stored in the header file for the signal recordings for later reference.
The base directory used to store recording files on the targeted storage drive.
This field can either specify the exact filename to which recorded data is stored, or it can be used to specify the starting characters for a filename that has additional information appended to it.
|Include In Filename
This option allows the user to select additional filename characters that can make the filename unique. If the None selection is made, the filename contains only the characters shown in the Filename Prefix field, specifying the exact filename for recorded data. The Date and Time selection forces the current date and time to be appended to the recorded filename. The prefix for the filename is contained in the File Prefix field. The Incrementing Number selection appends the next available integer numeric value to the File Prefix.
This option allows a file to be continually overwritten without the user question prompt of overwriting a file.
|File Span Recording
This option allows splitting the recorded file into multiple files. A File Size setting determines the approximate target size of each of the individual files. The filenames for the individual files have the characters “_partx” appended before the file suffix. The “x” starts at 0 and increments by 1 for each subsequent file.
Conducted signal recording operations will produce two files per recording session with the following file name extensions:
.stmrcd = Raw binary data file of the signal recording
.stmrcd.hdr = Header file for the signal recording
The raw binary data files (.stmrcd) contain only sample data values of the recorded signal; there is no file header or additional information contained in the raw binary data file. The non-proprietary file format of the raw binary data file allows for other 3rd party software applications to import and utilize the data easily.
The binary file format of the raw data file is ultimately dependent on the selected digitizer model instrument utilized and can contain 8-bit, 12-bit, or 16-bit based data. For multi-channel digitizer model instruments, active channel data is sample-interleaved within the raw binary data file; for example, a 4-Channel digitizer will produce a sample-interleaved file in this sequenced format:
CH-1, CH-2, CH-3, CH-4, CH-1, CH-2, CH-3, CH-4, CH-1, etc.
Since the raw binary files do not store any context information about the details of the data in the file, the second header file (.stmrcd.hdr) is also created with the raw binary file.
By default, header files are auto generated with the same file name of the recorded binary data file but with the added identified stmrcd.hdr file extension ending and resides in the same targeted directory location path of the recorded data file.
The header file is a small size generated XML-based formatted file that contains information about the associated recorded data file that includes items such as digitizer model, channel count, input voltage range, sampling rate, user text field notes, and more. The header files are easily read by any XML-aware software or text-based editor software application.
Selecting the Auto-Load Configuration Setup menu item displays the various options for configuration restoration. The configuration to be restored when the application is started can be the Last User Saved Configuration, the Last Auto Saved Configuration or no restore.
Before the application is terminated the current configuration is saved to storage. Once a setup configuration has been saved it can be automatically loaded on program restart if the Last User Saved Configuration is selected.
Each time the program is restarted with an enabled auto-load option, the digitizer selection is made when the program starts and is checked against the digitizer manufacturer/model in the configuration setup file. If there is a mismatch with any device, a warning message is displayed, and the configuration is not restored.
In addition to hardware configurations, the various display plot configuration layouts with color schemes can also be saved and auto restored when the application is launched saving time from having to re-configure display windows.
Multiple systems running the DsScope Server Edition can be accessed and operated as remote nodes with a single user interface over an Ethernet network with the Remote Client Edition. This is beneficial in cases where multiple systems, that may be dispersed in different locations, need to have acquisition and/or recording operations controlled without physical attendance at each system.
For network access to the remote nodes, all participating computers must be on the same subnet. Prior to configuring the remote client, all participating remote nodes must be powered up and accessible on the network.
In the remote client software, the Global Operations section contains the controls that operate on all participating remote nodes. The DsScope Nodes is a list of participating remote nodes along with their status. Access to the individual remote nodes is selected using the Network Node Tab. The hostname for the remote node is displayed on the label for the tab.
The remote client software includes a scripting tools editor allowing for automated control and operation of DsScope remote notes for easily repeating acquisition/recording sequences.
The script editor Server Information section displays the currently available remote nodes that can be included in the script operations. The remote node servers that are used in the script are also displayed to provide a cross reference to ensure that the desired remote node servers have been included in the script.
The Script Iteration Count specifies the number of complete iterations (loops) that the script will execute. This value can range from 1 to 1000.
The Script Instructions section is used to generate the script to be executed. Script instructions are added by clicking on the button corresponding to the instruction to be added. The associated instruction list section displays the order of script instruction execution.
As instructions are added to the list they are normally appended onto the last instruction in the list. As shown above, the instructions are appended since the Append mode is selection. Hitting this button toggles between Append and Insert modes. When in the Insert mode the new instruction is added before the highlighted list instruction.
The Load Configuration is used to select the targeted remote node specific configuration setup to be included in the script. The configuration setup must already exist on the remote node for it to be included in the script, and all available configuration files will be listed for possible selection.
A script validator tool performs a quick logical test on the script sequence to check for any inconsistencies.
While On-Board memory captures can be viewed and played back from directly within the DsScope application, Streaming mode-based signal recordings require the companion product DsScopeView application to open/view and conduct playback of previous signal recordings to the display monitor for analysis, with additional display capabilities that include persistence and histogram modes.
When opening previous streaming signal recording files, the matching raw binary data file (.stmrcd) and header file (.stmrcd.hdr) pair must exist to properly evaluate the recorded data.
DsScopeView has a control interface panel on the left-hand side of the application with the primary scope view (for multiple displays) occupying the main right-hand side.
The Control Interface Panel includes digitizer information and settings for Playback to display with Time Domain, Frequency Domain, and Spectrogram controls.
The digitizer information reflects data about the digitizer utilized for the conducted signal recording file as contained in the matching header file.
The Playback settings group controls the rate at which the application plays back the time domain data as well as the speed at which the displays are updated.
The Time Domain, FFT Units, Frequency Domain, and Spectrogram groups control settings all have similar functionality as previously described DsScope Time Domain, Frequency Domain, and Spectrogram displays all with similar scope cursor controls, zoom in/out, and panning capabilities.
The Persistence Display adds a historic frequency domain display to the application for a selected channel. The persistence plot holds 20 display scans of data acquisitions. It contains a color mapped area that represents the age of the spectral acquisition as a color. The range of colors is shown on the left-hand side of the display and is selectable with a color gradient selection window.
The Histogram Plot displays the tracked count of FFT bin occurrences over a period of time for a selected channel. In the histogram, each bin corresponds to a bin in the composite power spectrum FFT. After each composite FFT is calculated, each histogram bin is incremented by 1 if the bin value exceeds the user selected threshold. This provides a simple mechanism for filtering out frequency components that are not of interest and to verify the consistency of frequency components above a threshold.
The Linear/Log display selector controls the Y-axis display scale. The Log scale allows small bin count numbers to be effectively displayed in conjunction with large bin count numbers
A Histogram Threshold Selection is used to control the minimum power level detected in a bin before its histogram count is incremented.
A reset button sets all bin counters back to their initial value of zero. One may also force the bin counters to zero upon a specific number of acquisitions by enabling the Auto-Reset feature. The terminal count before a reset is applied in through the Reset Count numeric control.
Some fine grain selections for the Resolution Bandwidth may make the Histogram display difficult to discern due to the number of available pixels to display the histogram. One may either increase the width of the histogram display window or decrease the resolution bandwidth so that each bin is wider.
Export of Signal Data
DsScope provides an Export Split File feature to facilitate taking a large signal recording file and splitting it into smaller sized files for ease of manipulation and management.
This feature is also useful for the purposes of transferring smaller data file sizes that contain only the data of particular interest for review, rather than the entire original large signal recording file size.
The main recording file can be split into smaller files based on file size, recording duration, samples, or number of split files. Each segmented/split file contains a binary recording file as well as a corresponding header file that defines the content of the split file.
The original recording filename is used as the basis for determining the split filenames, but one may select an appropriate suffix to be appended to the main filename.
The generated split files can be located within the same directory as the main recorded file or located under a directory generated by the split file utility.
Once all the selections have been determined in the File Split Options section, selecting the Start button initiates the operation with a progress bar shown for indicating processing progress.
The primary advantage of DsScopeView is the ability to conduct playback of previous large streaming signal recordings to the display monitor for analysis.
Viewing File Details will display the details of the opened signal recording present in the header file associated with the recording data file for review. It includes basic information about the recording, applied digitizer model information, and settings utilized for the recording with total elapsed time duration of the recording file.
The various display types for Time Domain, Frequency Domain, Spectrogram, Persistence, and Histogram can all be effectively utilized for playback operations.
Playback operations utilize familiar navigation toolbar buttons for starting playback, stopping playback, stepping backwards and forwards, and moving back to start.
Selecting Start will initiate the playback through the entire signal recording data file to the active displays on the monitor. The playback operation can be manually stopped at any time by selecting Stop.
Selecting Step Backward causes the time domain display to step one interval backward, while selecting Step Forward causes the time domain display to step one interval forward. The amount of interval movement is dependent on the setting in the Playback Interval setting in the Playback Settings group. The step backward and step forward can either be by number of samples, time, or time domain plot size.
Selecting Move to Start rewinds the playback to the start of the recording. If the playback is not actively running when this selection is made, the file pointer is reset to the beginning of the file, but the display is not updated. You must continue playback or perform a step operation for a display update.
When the Enable Playback Looping option is enabled, the time domain data will loop from the end of the file back to the beginning when the end of file is reached. If the option is disabled, the playback ceases once the end of the file has been reached.
On playback, the processing block size (Playback Interval) and display update rate (Refresh Interval) have flexible adjustment parameters. These allow complete control over the file processing speed and display update rate.
The Playback Interval is adjusted by inputting the number of samples per block, or by directly specifying the time interval in either microseconds, milliseconds, or seconds. Alternately, the Playback Interval can be adjusted via the via the time domain x axis plot setting. In this case, the Playback Interval will be the same as the total time displayed on the plot.
The separate Refresh Interval setting controls the frequency at which the displayed plots are updated. The default setting is Fast, which results in the displays being updated as fast possible. The actual update rate is dependent on the number of open displays, and the block length of frequency domain plots. The selections for refresh rate: Fast, 200 mS, 500 mS, 1 S, 2 S.