Reference of all functions of Siglab - panel C functions.

 
These functions have no particular aims. The Sync button is very important.
 

Buttons	Shortcut	Result and Explanation
		y = S(x)-S(x-1). If x=1 (no for the first point worked out), then S(x-1)=S(1). Each time the function will be worked out, the first result will be 0.
		y = Sum((S(x)+S(x-1))/2) for all available points in the graphic window. BEWARE the result is wrong as integration does not start from the first point of the signal, but from the first point available in the graphic window for this signal. You are warned.
		Clamp on the chosen signal between the min and max value: It returns the signal between this two values.

 

1. Threshold

Threshold of a signal.
The threshold function returns 1 if the chosen signal samples are above the threshold or 0 if the samples are under the threshold. From this signal, it is very easy to construct a signal which has the original value if above or under the threshold. You just need to work out :

        y = threshold(S1,0.5)*S1

or

	y = S1*(1-threshold(S1,0.5))

This function allows to delay an existing signal. This works only for matrix file signals. Beware, it is not a new signal, but the existing signal which is delayed.

 

2. Spectral density

Work out the spectral density of a signal with the cspect scilab function.
The parameters are the following :

• signal : the signal to be used for the spectral estimation,
• first point : abscisse of the first sample of the signal, the spectrum of which will be worked out,
• width : nber of samples of the signal to be estimated,
• band nber : the nber of bands on which the spectrum is estimated.
• window type : a window (rectangular, triangular, hamming, hanning, kaiser, chebichev) is used for the estimation.
• beta : the beta parameter of the kaiser window,
• main lobe width : parameter for the chebichev window (please look at the documentation of window in scilab),
• side lobe height : second parameter for the chebichev window.

3. Upsampling

upsampling of a memory file signal.
Up sampling is only possible on a memory file signal. The whole signal is up-sampled. The parameters are the following :

• the signal to up-sample,
• the up-sampling factor,
• the "phase" of the up-sampling.

 
The output signal is :

         0 for all points,
         except : y((t-1)*factor+1+modulo(phase,factor)) = S(t);
         with S(t) the original signal samples.

 

4. Downsampling

Down sampling of a matrix file signal
The parameters are the following :

• signal to down sample,
• down sampling factor,
• phase of down sampling.

The output values are :

	y(t)=S((t-1)*factor+1+modulo(phase,factor))
	with S(t) the original signal samples

 

5. Merge

This function allows you to blend several signals in a single one.If you merge 2 signals, the first sample is the first sample of the first signal, the second sample is the first sample of the second signal, the third sample is the second of the first signal, ect...
Merge does this operation on the samples visible in the visualization window. The result is a matrix file.

S1=[S1(1) S1(2) S1(3) S1(4) ...]
S2=[S2(1) S2(2) S2(3) ...]
Smerge(S1 S2)=[S1(1) S2(1) S1(2) S2(2) S1(3) ....]

If you click on merge you will see the following interface:
Merge nber is the number of signal that you want to merge.
You have to click on DISP or type return to choose signals wanted.For exapmle if you want to merge 2 signals, you will get the following interface :
 

6. Split

Split sampling on a signal:
The parameters are the following:

• the signal to split_sample
• the split sampling factor
• the phase of the split sampling

 
If the signal is a matrix file the split is done on all the samples, else it is done the visible samples.
The output values are :

	y(t)=S((t-1)*factor+1+current_phase)

with S(t) the original signal samples and current_phase is phase modulo factor.
 

7. Sync button - your last chance

This is an important button. Something like "last chance button".
When processing new signals, errors may occure. For example you may divide a signal by 0. The result of that is that the creation signal processing will stop in the middle. Part of the values will have been updated, a new button will have been added but there is nothing to display.
This is not a rough error, but if you continue to work, it will lead to very unstable situations. All internal matrices to SigLab needs then to be "resynchronized". This is done in clicking on the sync button.
So, if something strange occures (for example a graphic with at the bottom a fully blank place), HIT THE SYNC BUTTON.