понедельник, 23 мая 2011 г.

SA update to version 6.2.4.8


SA Update to version 6.2.4.8.

This is the planned update.

In this version we are expanded number of SA tools by adding "In-band signal inverse" function.



This function provides qualitative enough inversion of the selected band of a signal or the whole signal, without affecting the other spectrum. It is required for the fast inversion of the signal, and as allows to restore/compensate or reduce various distortions in some cases. 


Example of operation with the distorted signal Icom UT-109





Distorted fragment.
Restored fragment.


Also range of minor bugs detected by users had been removed, some small corrections had been added.


Good luck!

пятница, 13 мая 2011 г.

Purple License.

Greetings!

Dear readers and SA users, we would like to inform you, that we have added new type of SA license - it is Purple License.



Often there is a necessity to acquire/get 7-12-15 or more SA licenses, for example for some educational institution or computer classes. For such cases we have added one more type of the license - Purple license. This license has no fixed amount of keys by default, the amount of keys should be specified and paid by user. The amount should not be less than 5 keys. We are hope, that this type of license will help to solve some questions concerning SA acquisition.

вторник, 3 мая 2011 г.

New Article: Perspectives of the analysis of OFDM signals with CP.

Perspectives of the analysis of OFDM signals with CP. 

As usual, we assume that reader possesses some basic knowledge concerning principles of formation OFDM, and the reader is acquainted with our previous articles, as terminology and the main ideas remain former. 

There are some general provisions. 

We already were being considered and showed in the previous articles, that at formation of OFDM signals the basic/main/key parameters are LS, LU and LG (CP), which are having dimensional samples. Basically, each one of these two parameters from these three (LS LU LG), unambiguously set the third parameter, as there is a simple correlation, namely: 

LS = LU + LG; 

We add one more, the dimensionless parameter, coefficient k = LG/LU or k = ((Sh/Br) - 1). This parameter allows to receive correct LS, LU and LG for specific conditions, besides k possesses mass of other remarkable properties, but it is beyond this article. 

In a general view the scheme of formation of OFDM signal with CP looks as follows: 








As we already considered, and I once again underline this moment, that there is no any Hertz and-or seconds! LS, LU and LG have at a stage of formation dimensionality of samples/samplings. We name it Fundamental/primary/key parameters of OFDM signal, these parameters are core of OFDM signal. All is equal to these parameters (samples), with what speed they will be transferred, needless to say, that transmission/transfer speed should be a constant.


As soon as some speed of following is given to samples (sampling rate of formation of OFDM signal OFDM), then earlier faceless values LS, LU and LG acquire/get dimensionality in Hertzs and-or seconds. But! They don't lose, and can't lose their main/fundamental properties. For example, as there was duration LS = 100, LU = 60 and LG (CP) = 40 samples, so it remains, irrespective of sampling rate.


There is one nuance in these transparent and logical enough conclusions. All what has been told above, concerns to so-called sampling rate of formation of OFDM signal.


In practice, to form a signal at once on operational frequency it is not convenient, and frequently it is not even possible. Normally, the signal should be formed on sampling rate Х, and further whole spectrum of the signal should be transferred on operational frequency Y. Thus, sampling rate X can't change duration LS, LU and LG, as it (sampling rate) is a consequence of existence of these parameters, and frequency of transfer Y can't destructively influence these parameters as it is not connected to them.


Let's sum up the told...


Full version of this article you may read here.


The arcitle contain examples on the real signals, schemes, detailed pictures, explanations and other interesting information.