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SA update to version
Phase Plane module, measurement of angles
Начало » Руководство пользователя SA
Разместил (Author): SergUA6 6.0
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SA update to version v

Update is concerned to Phase Plane module, also, minor disadvantages, which were detected by users and us, are eliminated.

The problem of the slow operation in Phase Plane on wideband signals is solved.

Now, the process of demodulation does not depend on sort of mapping of constellation, earlier it was not so, and correct demodulation was possible only in an absolute mode.

The algorithm of constellations mapping was changed. The colour graphic palette is changed. It improves visualization of constellations, and positively influences on quality of screenshots and videoclips.

The main feature of this update: Possibility to measure phase angles is added.

When function "Angles" is activated, the histogram of allocation of constellation angles is constructing in corrector window (parallel with constellation mapping).

This window has such structure:

upper half - area of positive angles mapping
lower half - area of negative angles mapping

From the right to left across, the distance from 0 to 180 degrees is developed. Accuracy of mapping and measurements approximately is 0.36 degrees on pixel, that is high enough.

Correspondence of the displayed histogram to constellation is represented below.

If to speak about PSK signal, then connection (correspondence) is direct and obvious. But, it is important to mark: positions 0 and 180 degrees (in case, they are present in constellation), that each of these positions belong to one own vector, and it does not depend on polarity of the histogram. It seems like it should be clear, but I pay attention to this moment, as for other positions on the histogram it is not so, both positive and negative values are different vectors in constellation.

In lower part of the form, current cursor position on an angular axis is displayed in two values:

1) the direct value (in the first field) - it is an angle from 0 to a cursor position
2) the reversed value(in the second field) - it is an angle from 180 to a cursor position

The histogram is continuously under construction in the course of constellation mapping, that is, there is an accumulation of results. The histogram image can be scaled by the regulator on the right side of the

After we got enough of results, and the picture is more or less clear, it is necessary to stop operation of Phase Plane module by button "Stop", and already directly on the histogram to make necessary measurements.

Having brought the cursor to peak on the histogram, you have to simply do clique by the left mouse button. The data will be written in the window of information output. In "clique" position the colour marker will be put. The colour of record corresponds to colour of the marker. By the reason of bad color difference on thin lines in colored areas, the marker has a thickness in three pixels, and the area of construction of the histogram has protective bars below and above, on which colour of the marker is well distinguishable.

The data is written in a following format:

1) the record number, this is conditional value and does not oblige to anything
2) an angle between a zero position (reference point) and marker
3) a difference of the angles between current marker and previous marker

These are standard enough values, which usually are interest first of all, and we have counted possible to calculate them at once.

In total, it is possible to put 10 markers, although usually two or three markers will be enough.

Right mouse clique on the histogram will remove all markers. Markers will be removed all at once together with measurement records.

The histogram is not under construction, if clock synchronization is switched off.

It is also possible to do all measurements without stopping Phase Plane operation.

Surely, In the near future there will be more detailed article with examples of operation with this function.

I want note, please read this is important:

Do not confuse position of a point in constellation, with an angle/vector, on which, this point is located, and which is displayed and measured on the histogram! That is, on the histogram we have radial angle/vector, on which lots of points can be allocated(for example QAM, PAM and other special modes), but NOT point position in the constellation as can seem at first sight.

Good luck~
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Файл создан: 15 Jan 2010 21:25, посл. исправление: 15 Jan 2010 21:34
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