Difference between revisions of "NVGate Output Signals"

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Objectives: this document aims at describing more in details multisine and random noise signal types in NVGate Software.
Objectives: this document aims at describing more in details multisine and random noise signal types in NVGate Software.


I/ Multisine signal type
Multisine is computed by adding sine signals whose frequencies are power of two sub-modules of sampling frequency. This means that multisine output block includes all discrete sine waves of FFT spectrum of corresponding block size and resolution. Multisine has the advantage of showing no leakage effect in FFT as all sine waves are exact periods of the trigger block for FFT computation. The most appropriate FFT weighting window to be used is “uniform” window. Multisine generators work on a sample block basis, it means signal blocks are repeated identically over time.
a/ Fixed phase setting:
Multisine phase relation if fixed and will be the same each time setting “fixed” is selected.
Phase relationship is the same for all multisine generators meaning that signal blocks will be the identical between any multisine generators of the same setting. Multisine fixed phase generators are 100% correlated.
 
b/ Random phase setting
Phase relationship between sine waves is selected at selection of setting and will not change unless “random” setting is changed back and forward. After “random” is selected phase relationship is defined (randomly for the first block) and repeated identically for each signal block of N lines. Phase relationship for all multisine generators will be different as random setting activation is made at different moment in time and applied for different generator objects. Two blocks of multisine random phase of the same generator are 100% correlated.
Two mulitsine random phase generators are not correlated.
c/ Using burst setting
Burst setting in Multisine generators will shorten time during which output signal is active despite signal block being of the same length.
All bandwidth frequencies are present in each burst but may not be complete cycles as block period is truncated. Two bursts being identical (respectively fixed or random phase) they are 100% correlated. Two burst random from two separate generators will not be correlated signals.




II/ Random noise signal type  
II/ Random noise signal type  
Signal block is recalculated each time. All frequencies of generator bandwidth are taken into account with a resolution of Fs/16384 (Fs being front end sampling frequency), this resolution is independent from FFT resolution. Consequently signal content of each FFT trigger block is not the same meaning that signals between two trigger blocks are not correlated. Similarly random noise signal between two separate generators are also not correlated.
Signal block is recalculated each time. All frequencies of generator bandwidth are taken into account with a resolution of Fs/16384 (Fs being front end sampling frequency), this resolution is independent from FFT resolution. Consequently signal content of each FFT trigger block is not the same meaning that signals between two trigger blocks are not correlated. Similarly random noise signal between two separate generators are also not correlated.
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