четверг, 21 мая 2009 г.

DIGTRX is the very interesting signal. Fresh analysis.

Author: SergUA6
DIGTRX signal.

Band Width ~1830-1850 Hz
Low Range ~300 Hz, shift is possible, receiving is in SSB
Baud Rate 122.5
Hz n-Ary (PSK/MPSK) special differencial PSK-9
Count of Carriers 8 perfectly visible freqeucnes of manipulation
Step between carriers 230 Hz
The modulation, in which the signal was recieved (RX mode) SSB

The example of the signal is here

Sonograms:
pic.1 general look of the signal
pic.2 spectral differencies in the channels

pic.3 speed of manipulation
Diagrams:
pic.4 the constellation in the channeles 1,3,4


pic.5 the constellation in the channel 5

pic.6 the constellation in the channels 5,6,7,8

Illustrations:
pic. 7 generall organisation of change-overs

DIGTRX - it is the very interesting signal, in which special differential modulation DPSK-9 is used, a bit unexpectedly.
The signal is bright enough. In Signals Analyzer features are well visible both to manipulation as a whole, and to distinctions in channels. Here is the very interesting circuit of difference manipulation.
The general organisation is shown on
pic 7., it does not exclude change-over from a position +3 in -2(for example), but it allows to notice, that change-over from +4 to -4 has smaller vector's lengh than the others, that is already interesting in itself, besides, this change-over is also working(operating) and actively used.
From
pic6. it is possible to understand the reason of instability of the constellation in PSK-4 mode, it is well visible that this short change-over from +4 to -4 is exactly that "the disturber of calmness", which on the one hand imitates PSK-4, but on the other hand it does distract PSK-4.
Surely, this is the very interesting signal.