SA: How to work with OFDM module. How to apply new features of OFDM module on practice. Practical examples on real signals from the air.

SA - how to work with OFDM module.

Several practical examples on the real signals.

Full version of this really interesting tutorial is here.

After version 6.1.0.5 and article SA OFDM module, constellations in channels has appeared, we received several letters with questions about how to use OFDM module and what are practical possibilities of constellations in the channels.

Even taking into account those difficulties, which have been described in previous article, SA OFDM module represents powerful tool. Operation with this tool we will be considered more detailed in this article.

In this small tutorial we took 4 real signals from the air to work with in SA OFDM Module.

Here is the signals from the air, which are used for analysis in this tutorial:

1) DAB

2) OFDM-59

3) WinDRM

4) Q15X25

I do not post the whole artilce in the blog, because it will take too much space, not because of text, but because of pictures.

Please, follow the link to see whole article with all pictures, and interesting features inside.

My personal opinion: It will be very interesting to read for everyone.

WINDRM 51-Tone COFDM Modem

WINDRM 51-Tone COFDM Modem

Amateur mode, Br-37.5, Sh-46.875, Ch-51, QAM-64

Here is the example of WINDRM signal

Author: SergUA6

Band Width 2400 Hz

Low Range 300 Hz

Baud Rate 37.5 Hz

Count of Carriers 51

Step between carriers 46.875 Hz

Pilot tone(s) 3 pilot tones 750, 1500 and 1875 Hz

ACF 400 ms, brightly expressed period

RX mode SSB

Sonograms:

pic.1 General view

pic.2 Graphical spectrum

pic.3 Allocation of channeles

Diagrams:

pic.4 Constellation of the lower channel, start.

pic.5 Constellation of the lower channel

pic.6 Constellations in other channeles

Pictures:

pic.7 ACF

WINDRM 51-TONE - difficult enough sort of modulation mastered by hams, the "industrial" basis is certainly visible, many things are taken from standard DRM. 400 msec frames and the circuit of a rating/spacing of pilots-tones are made by analogy of "big DRM", all accessible frequency resource of 2400 Hz is completely used. SA possibilities allow to receive both signal parametres, and constellation in any channel. It is well visible that QAM-64 is with various service "design", there are also channels with "pure" QAM-64. Maximum technical speed is 10800 bps.