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.

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).

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.

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. 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 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.

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.