OFDM, COFDM: CIS-79, conditionaly name TANDEME

CIS-79, conditionaly name TANDEME

Ch-79, QAM-64, Sh-37.5, Br~30.476, k = 59/256

OFDM, COFDM

The signal is here. Send by YuriVR.

Author: SergUA6 

Band Width ~3000 Hz

Low Range ~350 Hz

Baud Rate ~30.476 Hz

n-Ary (PSK/MPSK) QAM-64 and PSK-8

Count of Carriers 79

Step between carriers 37.5 Hz

RX mode SSB

Sonograms:

pic.1 Generall view

 pic.2 Normal symbol and destroyed by distortions symbol

Diagrams:

pic.3 The constellation in the special/service channeles

pic.4 Full constellation of the channel

CIS-79, TANDEME - Russian native signal, which full analysis was realized by participants of  "power group"  of our forum. From singularities it is necessary to mark a preamble. This preamble isn't OFDM part, and represents an independent special fragment. Also usage in service channels of modulation PSK-8 is curious enough. The record completely corresponds to initial parameters of the signal, and thereupon rather explicitly can be studied in SA without special problems. Despite high quality of the material, there are destroyed symbols, which as are perfectly visible at the detailed review in SA, it is the result of an overload at signal's recording.

Update SA to version 6.2.4.6

SA Update to version v 6.2.4.6

Support of 64 bit data with a floating point is added. 

The algorithm of operation of OFDM module had been essentially changed.

"One-dimensional" search of a correlative triangle(CT) which had been realized in the previous versions, possesses imperfection. The probability of detection/finding CT, depends on signal shift on/by frequency, and sometimes the algorithm is mistaken.

Problem is not in the fact that it happen rather rare, and in that, if the triangle hasn’t been found out there are no any warranties that the triangle really doesn't exist.

In the current version of OFDM module another algorithm of "two-dimensional" search (terminology belongs to our mathematic) is implemented. This algorithm provides much bigger guarantee of findings CT, and besides it has reserves for optimization. In spite of the fact that in the computing/calculating relation the new algorithm is much more resource-demanding than the previous one, the general speed of finding/detection CT, is increased in 6-7 and more times, especially it is noticeable on the big dimensionalities LS, for 600-800 samples and above

Possibility of relocation of the green marker through the keypad is added. It works only in a dynamic mode, as in the static mode there is no big sense to “walk” on channels.

Some utilitarian actions in OFDM module has been automatized, for example, in the current version the program tries to install CT in an optimal position independently. Accuracy of calculation of clock rate(Br) is increased.

Also work/operation of some separate functions and procedures is reconsidered/optimized both in OFDM module and in other modules.

As usual, except the described changes, a range of internal corrections is realized, errors found out by users has been fixed.

This update affects and changes a little bit the general scheme of actions at analysis OFDM. Though these changes are rather insignificant and directed on simplification of procedure of the analysis, nevertheless, we will provide the small article about an operation with the current version in the near future.  

Good Luck!