среда, 23 марта 2011 г.

Update SA to version 6.2.4.4

 
SA update to the version v 6.2.4.4 

We continue to increase SA power and abilities, we expand possibilities of OFDM module of the analyzer in this update.
 

1. In display of OFDM signal spectrum  small pedestal/platform in 10 pixels is added. It allows to see all line of channels current/investigated LU.

2. Possibility to display on phase planes only every second, the third etc. symbols  is added.

3. Possibility to shift/replace a start point is added during dynamic mapping. In a combination with the previous element, it allows to find out/study rather effectively various special channels/symbols in signals.
As an example there is one service channel of signal WinDrm is shown below.


For comparing it is shown as it looks/looked in old versions.


Important! The second and third points of updates, work only in a dynamic mode!

This update considerably expands analysis OFDM  signals, bringing it on qualitatively higher level.

Small manual on the technician of OFDM analysis  by means of current version SA are described in the article the Overview article (manual) about  the analysis of various OFDM signals in SA versions v 6.2.4.4

Good luck.

пятница, 4 марта 2011 г.

Examples of using MFSK demodulator in SA v 6.2.4.2

 Examples of using MFSK demodulator in SA v 6.2.4.2 


In this article, we will consider examples of usage of universal MFSK demodulator in SA version v 6.2.4.2 


Practically, any FSK/MFSK signal can be demodulated to a bit-stream in SA last versions. Here is, when we say "any" we mean, that there is nothing known about a signal initially. Also it is meant that necessity for obtaining/getting of the bit-stream can arise at any moment, on any signal, or any part of a signal. 


The Example. The record of an unknown system in a VHW band ~900 mHz. 



Step by step guide of main actions is shown below: 

Step 1. Select a necessary/interesting fragment of the signal and create a copy. 

Step 2. Select a necessary/interesting band of the signal and move it in a bottom. 

Step 3. The Main objective of the previous step is the reduction of sampling rate to an optimal value. Initial record has sampling rate 68 mHz, and it has sampling rate for the signal, which is interesting us with the full spectrum in ~ 180-190 kHz is absolutely superfluous. 

The mechanism of the abstract frequency conversion of sampling rate is built in SA, that is to us it doesn't matter which sampling rate will be specific, it is important that it would be optimal. It works as follows, and we had already wrote about it in one of updates. 




In the same way works the abstract shift of a signal by frequency. It is also doesn't matter to us which position the signal occupies, but it is important that it would be in optimal position by frequency on sonogram. 

Let’s come back to the signal. 

The full version of this guide-article you may read here.