понедельник, 25 мая 2009 г.

New: SkyOFDM the family's OFDM signals

SkyOFDM the family's OFDM signals
Shift~86, Br~64.1, Mode-PSK-2(4)

the example of this signal here(22 channeles) and here(28 channeles)

Author: SergUA6
Band Width ~2000,2400 Hz
Low Range ~580 Hz, shift is possible, recieveing in SSB.
Baud Rate ~64.1 Hz
n-Ary (PSK/MPSK) PSK-2(4) in this records PSK-4
Count of Carriers 22, 28
Step between carrier ~86 Hz
ACF (auto-correlation function, periods) ~78 ms
RX mode (the modulation, in which the signal was recieved) is SSB

Sonograms:

pic.1 general look of the 22th channel

pic.2 detalization of 22th channel

pic.3 speed of manipulation in the channel


Diagrams:
pic.4 general look of 28 channels

pic.5 detalization of 28 chanelles

pic.6 the speed of manipulation

Illustrations:
pic.7 the phase constellation in the channel, the bottom channel

pic.8 speed of the special insertions

pic.9 VMW, generall structure of the signal


SkyOFDM – It is the protocol, which is appeared in the last versions of the program Sky Sweeper, probably it is their own original development.
The signal is bright enough, it has a lot of features and easily identified and recognizable.
Features of the forming spectrum are well visible on the pictures 2 and 5, it is both - the characteristic preamble, and not suppressed out-of-band channels, one is on the bottom and two on the top.
It is well visible, in VMW, that every fifth OFDM character(symbol, sign) is special, that should give approximately 12.8 Hertz after a capturing of envelope(it is represented on the pic.8.).
From discussions on our forum it is visible, that there are lots of parameters of the signals, and these parameters are combined, it means: the quantity of channels, the speed of manipulation, the
preamble and the manipulation mode in the channel can vary, but for all that there should be common features, for example the characteristic typical insertions, which are visible in VMW.
Probably it is not the development of Sky Sweeper command, it can be some more common protocol or some principle of forming, but the exact data is not present yet.

MSM team.