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DSAP Studio

DSAP Studio is a digital signal analysis and processing tool (DSP). DSAP Studio allows a discrete signal or its spectrum to be read in a specific format, Fourier or inverse Fourier analysis of the signal, and digital filtering. Short Time FFT analysis with spectrogram is available.

DSAP Studio is visually divided into 3 modules: Input, Filter and Output. Each module has domain for signal (time-domain) and spectrum (frequency-domain).

Both linear and logarithmic representation (for both X- and Y-axis) can be used for spectral data. If the spectrum is displayed in logarithmic format, the scale is also in logarithmic (decimal or octave) format.

Settings

Misc|Settings. Opens flyout form for general settings. It is possible to:

Show or hide panels (modules) of signal and spectrum: In(put), Filter, Out(put).

Precision of checking of complex spectrum, default is 1E-12.

Significant numbers: 1...10. Default is 5, in trial version it is also maximum limit. Numerics are shown in specified significant numbers (can be modified in settings, default is 5, in the trial version it is between 1 and default, in the full version it is between 1 and 10) using scientific notation. When the value is in the range between 10-30 to 1030 the according metric prefix is used (from q - quecto to Q - quetta). 

Maximum number of signal components in signal generator, default is 5.

Signal or spectrum saving format. Options are to save all the data (amplitude, phase, real, imaginary parts of signal or spectrum samples) or for use to upload to R&S RTC, RTB, RTM or RTA series oscilloscopes.

Computing power. Serial or parallel, serial uses only 1 core of a processor, parallel uses all the power of a processor. Due of lag  of a operating system for shorter signals or spectrums a serial computing might be faster.

Length of a spectrum graph. Two options, full with imaginary frequencies, half for real frequencies only.

Precision of calculations: Double or float as co-data. Figures in float precision would be additionally to double figures.

Interpolation. Options to connect and show (display) signal graph when there are less samples (points) in signal than horizontally pixels on module window. Linear or sinc function based interpolations are available to use.

Level mark. There are 4 kind of level marks.

Spectrogram (not available in trial). Show or hide and choose a maximum lines on spectrogram. Spectrogram part opens below of spectrum part of each module. Choose a window function before start a processing.

Display graph with custom padding vertically between 0-30% of full vertical range.

Show info (timestamps). Shows or hides processing time of FFT or iFFT.

Setting will be saved and after pressing of OK button. Saved setting will be reloaded in start of a next session. Reset loads default settings, Cancel does not save changes.

Load

Load. User can load data to each module from .csv file or from supported oscilloscope. 

Direct download from oscillososcope. From supported oscillososcope it is possible to load waveform data directly via TCP/IP Socket connection and DSAP Studio app knows how to obtain this data. Secondly for certain devices there is also knowledge about byte-order of obtained data, so app knows how to display obtained data. When byte-order is not known the user should change byte-order when obtaining the data.

Direct download from the instrument is available with annual and monthly subscriptions. If there is no license, the DSAP Studio app offers to obtain one of these two options as an in-app purchase.

Supported oscilloscopes (as of version 4.1 - Aug 2024, extended functionality available as a Subscription) for direct download of waveform data through LAN socket connection:

Rohde & Schwarz RTB, RTA series, signal and spectrum (tested),

Rohde & Schwarz RTC, RTM series, signal and spectrum (untested),

Rohde & Schwarz MXO, RTO series, signal (untested),

Siglent Technologies SDS, SHS series (untested),

Rigol Technologies DHO, DS series (untested),

Keysight Technologies DSO(X), MSO(X) series (untested),

Tektronix MSO, MDO, DPO series (untested).

If it was possible to find out from the manufacturer's data whether the oscilloscope supports the byte order command, the oscilloscope data will be displayed correctly. Otherwise, try changing the byte order setting in the connection form to get the correct view.

Reading data from .csv file. Direct support is built for R&S RTC, RTB, RTM and RTA series oscilloscopes. For other cases it is possible to use option "Other .csv". You can set line and column from where data starts and how the data is organized on file.

Save (Export)

Save. Export of the data. By exporting the data (saving to a .csv file) you can choose between DSAP Studio format and R&S RTC, RTB, RTM, RTA format (as set in Setting form).

FFT

Computes a spectrum from a signal using the Fast Fourier Transform (FFT) and displays it in the spectrum window. By default, two graphs are displayed, one for amplitudes and one for phases.

The frequency representation of both graphs can be selected either on a linear or logarithmic scale, for the logarithmic representation, in turn, you can choose a decade or octave representation.

The vertical display of the amplitude graph can be selected on a linear or relative (logarithmic) scale. On the linear scale, the values ​​are either V or A, on the logarithmic scale it is also possible to choose between dB, dBm (50 Ω), dBV or dBμV. The values ​​are displayed on the left side of the window, and both the graph and the amplitude values ​​are displayed at their maximum extent by default. 

In the settings, it is possible to adjust the amount of padding in the vertical direction, so that the extreme parts of the graph are more visible and do not reach the lower or upper edge.

The vertical display of the phase graph is always linear and the phase scale is on the right side of the window. The unit of phase is always the radian.

Depending on the selected setting, the spectrum graph is displayed either with complex frequencies or only with real frequencies.

At the top of the spectrum window, you can see the sampling data, the number of samples, the frequency step and the sampling rate.

When moving the graph with the mouse, the graph point information, sample number, number of samples added to this graph point, frequency, frequency range, average amplitude, maximum and minimum size of sample amplitudes, average phase, maximum and minimum phase of samples are presented at the corresponding frequency location. If there is only one sample per plot point, the mean values ​​are not reported.

You can use the mouse wheel to zoom while on the graph, and you can also specify the zoom using the context menu, which opens with a right mouse click.

The zoom status is shown at the top of the window.

iFFT

Computes a signal from the spectrum using the Inverse Fast Fourier Transform (iFFT) and displays it in the signal window. By default, two graphs are displayed, one for amplitudes and one for phases.

Signal graphs are presented on a linear scale so that the amplitude values ​​of the graph are on the left side of the window, the phase values ​​are on the right side. The amplitude unit is V by default, but it can also be imported from A or W. The phase unit is always radian.

In the settings, it is possible to adjust the amount of padding in the vertical direction, so that the extreme parts of the graph are more visible and do not reach the lower or upper edge.

At the top of the signal window, you can see the sampling data, the number of samples, the time step and the sampling rate.

By moving the mouse on the graph, the graph point information, sample number, time, time range (to the next displayed point), amplitude and phase are presented at the corresponding time point. If there are more samples in the signal graph than can fit in the display window, then decimation is used (only the sample corresponding to this window point is shown).

You can use the mouse wheel to zoom while on the graph, and you can also specify the zoom using the context menu, which opens with a right mouse click.

The zoom status is shown at the top of the window.

Phase values ​​appear on the signal as a result of the inverse transformation. They are mostly extremely small, in attoradians (10E-18).

Signal generator

Signal generator. When no import data is available it is possible to use app's generator to generate signal waveform for Input module. Signal can be composed from multile components which will be summed together for final signal waveform: sine, rectangle, triangle, pwm and DC.
Components may have each own amplitude, frequency, phase shift (not relevant for DC). For PWM signal duty cyle can be choosed.  

Also noise can be added: white, pink, red, blue or violet with own amplitude. 

For sampling the waveform a sampling frequency and number of samples are needed. 

To show the waveform use of two option for interpolation are possible: linear or sinc function. 

As of version 4.3.1 the DSAP Studio app does not check if the sampling frequency is more than twice of the maximum signal frequency. If this condition does not meet you can see aliasing. 

Only the noise can be generated if at least amplitude of main component is set to 0.

Digital filter

Digital filter setup.  Filter module allows to set-up filter spectrum. There are low-pass, high-pass, band-pass, band-stop and arbitrary filters. Arbitrary filter gives way to set-up complicated filter characteristics. Therefore firm that spectrum you can generate filter response signal and get coefficients for digital filter.

When entering arbitrary filter breakpoints, a decimal prefix can be added immediately after the numeric value, for example, enter 60M to get a frequency value of 60MHz. 

NB! Prefixes are case sensitive, m = milli, M = mega.

Extra care should be taken when cut frequency(s) is (are) set near to half of the sampling frequency and number of samples is low. Step of frequency might then include both the cut frequency(s) and half of the sampling frequency and graph will be one horizontal line without step(s).

Output module shows filter output when certain filter has been applied to input signal.

Context related functions

Drop-down flyout context menu on signal and spectrum modules. A mouse right-click opens a context flyout menu on signal or spectrum part of input, filer or output module with choices: Legend, Amplitude (Hide, Show), Color of amplitude graph, Phase (Hide, Show),  Color of phase graph, EMC (Hide, Show), Color of EMC graph, Change graphs order, Zoom, Level, Leveltable (Show, Hide), Histogram (Show, Hide), Window function (not available in spectrum part).

Legend. The legend shows graph names and the according colors.

Show|Hide graphs. You can decide to show or hide each graph, settings are remembered.

Graph colors. It is possible to change the color of each graph by the user's will. The choosed coloring is remembered.

Change graphs order allows to reorder the visible order for the graphs, what is on the foreground and which stays on the background.

Zoom. To zoom into the waveform (signal or spectrum) you can scroll with the mouse scroll button on the waveform window or right-click on the window and choose zoom from the flyout menu which gives a more sophisticated way to zoom up to arbitrary set start and stop domain values.

Level. It is possible set a specific level for signal or spectrum and analyse filtered transient samples. This is useful when signal or spectrum has more samples than display can represent and some interesting samples are decimated or averaged to overall level.

Level and leveltable. You can set level-line and leveltable collects graphvalues which are very close to that level and shows also transition direction.

Histogram is available (show/hide using context flyout menu. You can activate a histogram for visible graphs but not for EMC reference graph.

Window functions can be used, in trial version only Hamming, in full version rectangular, triangular, Hamming, Blackman, Blackman-Harris, Hann, Flat-Top, Welch, Gaussian, Tukey, Kaiser-Bessel window functions.

Legend

Legend. The legend shows graph names and the according colors. The legend follows change of color of the graph.

Graphs visibilty and color

Show|Hide graphs. You can decide to show or hide each graph, settings are remembered.

Graph colors. It is possible to change the color of each graph by the user's will. The choosed coloring is remembered and changes on graph follow current choice on coloring flyout.

Change graphs order

Change graphs order allows to reorder the visible order for the graphs, what is on the foreground and which stays on the background.

Zoom

Zoom. To zoom into the waveform (signal or spectrum) you can scroll with the mouse scroll button on the waveform window or right-click on the window and choose zoom from the flyout menu which gives a more sophisticated way to zoom up to arbitrary set start and stop domain values.

The colored ribbon follows color of the graph and highlighted part gives a location of visible part of the graph.

Level and leveltable

Level. It is possible set a specific level for signal or spectrum and analyse filtered transient samples. This is useful when signal or spectrum has more samples than display can represent and some interesting samples are decimated or averaged to overall level.

Level and leveltable. You can set level-line and leveltable collects graphvalues which are very close to that level and shows also transition direction. Activating certain crossing record in levetable marks the crossing location on graph with level mark (a little diagonal cross). There are 4 kind of a shape for the diagonal cross.

Level marks

There are 4 kind of level marks (diagonal cross): accordingly Mark 1 - simple, Mark 2 - with notches at the ends, Mark 3 - with straight ends, Mark 4 - with spikes at the ends.

Level value

The level value can be specified or the level line can be moved with the mouse.

If there is no possibility to select a prefix with a decimal next to the value entry field, then the letter corresponding to the prefix can be entered without a space immediately after the value.

NB! Prefixes are case sensitive, m = milli, M = mega.

Cut or pad a signal

Cut, Pad. For signal and filter response signal cutting and padding there are options to free setting or by integer power of two (end, start, both sides).

The colored ribbon follows color of the graph and highlighted part gives a location of rest part of the graph when cutting or existing part of the graph when padding.

Histogram

Histogram is available (show/hide using context flyout menu. You can activate a histogram for visible graphs but not for EMC reference graph.

Window functions

Window functions can be used,
in trial version only Hamming,
in full version
rectangular,
triangular,
Hamming,
Blackman,
Blackman-Harris,
Hann,
Flat-Top,
Welch,
Gaussian,
Tukey,
Kaiser-Bessel window functions.

Frequency scale of spectrum

Frequency scale for spectrum is linear or logaritmic. When logaritmic there are options for decade or octave grid.

Amplitude scale of spectrum

Amplitude scale for spectrum is linear or logaritmic. When linear only the absolute values V, A are possible (others are grayed). When logaritmic there are options for absolute values V, A and relative values dB, dBm (50 Ω), dBV, dBμV as well.

EMC

EMC. For spectra analysis it is possible to load EMC data for reference. Color of the EMC graph can be chosen also to get a better separation and visibility. EMC analysis is available in yearly and monthly subsciptions.  If there is no license, the DSAP Studio app offers to obtain one of these two options as an in-app purchase.

STFT

STFT - Short Time Fourier Transformation. The selected input signal is chopped into pieces of selected length, each of which is applied a separate FFT. Each such transformation is presented as a separate line. In this way, the frequency changes of the time-varying signal and possible deviations can be clearly seen if a uniform signal and correspondingly uniform spectrum are assumed. Each line is a separate time interval and the color presented in the line represents the amplitude of the spectral component, a lower amplitude is usually a cooler color - a bluer tone, a higher amplitude is presented again with a warmer or redder color.

STFT processing is not available in trial version.

Transforms

The DSAP Studio app not only calculates transfom of input signal and filter signal response to get output signal but it is possible to get input signal from output signal and filter signal response, and filter signal response from output and input signal.

FFT of the input signal - X[z], FFT of the filter response signal - F[z], FFT of the output signal - Y[z].

The output signal: inverse FFT of Y[z] = X[z] × F[z].

The filter response signal: inverse FFT of F[z] = Y[z] / X[z].

The input signal: inverse FFT of X[z] = Y[z] / F[z].

SI metric prefixes

In addition to the widely used SI prefixes or metric prefixes, there are also less common prefixes, the most recent of which were introduced only in 2022. For the sake of clarity, here is a list of all prefixes in use today, from the smallest quecto - q - 10-30  (below) to the largest quetta - Q - 1030 (top):
1030 Q quetta
1027 R ronna
1024 Y yotta
1021 Z zetta
1018 E exa
1015 P peta
1012 T tera
109 G giga
106 M mega
103 k kilo
100 - -
10-3 m milli
10-6 μ micro
10-9 n nano
10-12 p pico
10-15 f femto
10-18 a atto
10-21 z zepto
10-24 y yocto
10-27 r ronto
10-30 q quecto

Windows themes

The DSAP Studio app supports Windows themes by default. Whether you like a dark or light background depends on the user's personal preferences. This does not change the color chosen for the graphs, so for example a yellow graph line can be hard to read on a light background. At the same time, the user can always set the colors of the graph line as he wishes, the Legend can be found in the context menu.

Licensing

From April 1, 2024 there are available 3 kind of purchases and trial.

Subscriptions. Yearly and monthly subsciptions allow equal extended funcionality of DSAP Studio app. 

Life-time license. One-time fee gives basic functionality. No EMC analysis. No direct obtain data from network connected oscilloscope.

Trial. Offers limited functionality. No spectrogram. Significant numbers of data are limited to 1..5. Only Hamming window function. Only 4 lines of signal, spectrum or filter coefficent data will be saved.