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.

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.

Record for the following analysis.

If you record the signal just for yourself, then you can do not read all that follows bellow. But if you are making
the record, specially, to represent it to public, or to give it for further analysis, then you must take care about
quality of this record.

Good quality of the record of the signal – is the half of success.

1. Never record with digit capacity of 8 bits. This 8bit mode suits to everything, but only not for finding-out of
nuances of the signal’s structure. Use only 16bit. That is not the point, that 8bit it is bad, the point is that
16bit, by default, provides the quality, which is enough for analysis and disassembling, while 8bit provides such
quality only in very rare cases. There is also no sense to convert the record from 8bit into 16bit artificially – it will be self-deception: all subtle connections inside the signal will be lost irretrievably.
Forget about recording from a microphone, it will be the fatal end of your record, don’t even not think to publish
it, only a linear output, or in extreme case, an output on ear-phones.

2. Never write the record in the compressed format at once. The record if it is really interesting to you, and in
some sense is precious, should be written in the pure form, without a compression – in the old kind WAV format.
underline, not some sort of WAV format(for example ADPCM and many others), but namely the pure PCM WAV standard. The original record should have the highest quality, then, if possible, it can be compressed, but if to compress it at once - an initial clear picture of the signal will be lost and not available for restoring any more. This is very bad because, there are lost of situations, when not compressed signal can be demanded easily.

3. It is necessary to approach with all gravity and seriousness to the record’s sampling rate - for a large number of signals the sampling rate should be not below then 11025 Hz, that provides the upper boundary of a range on the level about 5.5 kHz. For the record of satellite signals it should not be lower then 22050 Hz.
Do not hope that it is enough 8kHz sampling rate for telephone channel, all this is true, but in terms of monitoring,
particularly on HF, the inaccuracy of the settings and features of the modulation can easily deflect the signal from
the telephone channel and the "unnecessary" half kilohertz is not only interference, but the guarantee of deflection.
Only after the record is done, it is possible to reduce the sampling rate, by results, if it is required. The records
of satellites are, generally, easily overlapping upper boundary for 6-8 kHz , thus, remember - the sampling rate for them should not be less than 22050 Hz!

4. Never make the record without preliminary check-up/setup(setting), of path(tract,route) of the record. There is nothing worse, than the rare record, which is made with an overload.
Such records do not cause anything but regrets, it is impossible to understand them, to result them into normal kind is also impossible, you can only throw them out into basket.
Pair of the minutes, which are have been saved by the lack of knowledge or by the laziness, will expressed in a waste of time and an absolutely useless resources.
The maximum signal’s level at the recording should not exceed half of the possible maximum, thus guaranteed the
existence of at least some reserve, in case of any surprises.
It is better to write with certainly reduced level, than with certainly high.
Weak level can be raised, while the overload in the record cannot be removed by any weakening , the signal’s
form/shape will be distorted to unrecognizability.

5. If you turn the receiver with purpose to write something "special", then immediately turn on the record. There are a lot programs, which are writing the record into long file, personally I use RecAll, it writes, while I’m busy withmonitoring. The point is that the rare and interesting moments are always occur unexpectedly, and they are very short, the vanity, which is arising from convulsive attempts to launch /run/start recording program, leads to the fact, that neither the record nor the signal is there in the end. When the record goes permanently, the risk to skip something interesting is about zero, it is necessary only to be provided with reasonable time of the record into "a ring" file, for me this reasonable time is about an hour.

6. Do not do anything with the record, do not improve it and do not try to make it look better, leave it fully "as it
is". You can easily corrupt it, and what you seem as " unnecessary" can play the very important role in the analysis.

7. Okey, so the record is have written, and everything seems good to you, you want to public this record for an
identification or for other purposes – please be careful, do not create illusions, view the record by any editor or a
software, and check what is exactly you got in that record.At least estimate the form of the signal: there should not be any restrictions by the amplitude or any unexplained strangenesses. If you do not understand what is happened within your record, then others, most probably, won’t want to understand it especially.

And in conclusion: To make a good record - it is same work and skill as all other professional skills, nothing can
be well-done by itself. Train, try, play in quiet conditions. Look what is overload on practice, check what reasons
cause overload, try to remove it, learn how to define it.
It is not enough just to have a knowledge, it is necessary to know how to apply this knowledge, the only one method to know it – is the practice and experience.

Author SergUA6

XSL - Japanise Slotmachine itself

XSL - Japanise Slotmachine
Japanise Navy? PSK-4, Br-1500

the signal

the synthesis-model of the signal


Author: SergUA6 6.0
(Band Width) ~2000-2050 Hz
(Low Range) ~400 Hz, shift is possible. recieving in SSB
(Baud Rate) 1500 Hz
n-Ary (PSK/MPSK) 4
(Carrier frequency) ~1512 in this record. shift is possible. recieving in SSB
(ACF) ~94-100 ms
(RX mode) SSB

Sonograms(pictures 1,2,3)

pic.1 The general look of the signal

pic.2 manipulation speed

pic.3 4th harmonic of the signal

pic.4 Diagrams (phase constellation of the signal)

XSL Japanise Slotmachine - is the popular enought signal, and at the same time, it is very difficult for the analysis. Complexities are connected with the quality of records first of all. From all variety of the found files, only that record has allowed to analyze the signal well. The signal is very bright as we can hear, and as we also can see on the spectrum. These two factors, together with ACF, allow to identify the signal very reliably.

The example of the analyzed signal

The ACARS VHF signal
AirSystem

the signal is here http://signals.radioscanner.ru/base/files/signal24/f1.wav

Author - SergUA6

Band Width - 2400-2700 Hz

Low Range - 300-400 Hz

Baud Rate - 2400 Hz

Count of Carriers – There are two practically not distinguishable frequencies of manipulation,
with strongly fixed values of 1200 and 2400 hertz, hard fixing is provided by a transmission mode with AM(amplitude modulator).

Step between carriers - 1200 Hz

RX mode – AM

Sonogram pic.1

Diagram pic.2

Diagram pic.3

ACARS VHF - it is one more system that is used in aircraft, in difference from HFDL, it is used only on VHW and only in AM mode, range of operation is limited by a working range of used frequencies and does not exceed 400-500km. Modulation of radiation is АМ, the signal represents GFSK manipulation with carriers 1200 and 2400 hertz and with speed of manipulation of 2400 hertz. There shouldn’t be difficulties with identification of this signal. At first there are no any signals in AM mode in aviation range with such characteristics, secondly the signal has features, which are very well visible after demodulation(check graphics), thirdly the signal has standard frequencies, which are must be known, because, by virtue of the very short time of transmission, to meet these signals accidentally is very hard.

This signal is analyzed and ready for decoding.

What SA project is?

Air is full of different mysterious sounds. For some people these sounds mean nothing, while for others it is the whole world of signals. As far as our team is in total passion with analysis of the signals, we have decided to help everyone, who is into ham sphere and interested in the signals. Therefore, since SA project was started, we got lots of letters and questions about different signals. People send us various signals and ask to identify them. Here goes one of the main goals of SA-it is to help everyone from professional analysts to amateurs in such not easy task as analysis of the signals. We surely can say that SA program has unique set of tools, which allows to do very high-quality analysis of the various signals and also unclear, strange, unknown signals.

So, it is very important to understand the place and goals of the signals analysis.
And this question should be considered from the start. Why do we catch and record all these signals and records? We want to open a secret what is inside of either, one or another signal. We want to decode it. But can we just record some signals and put them into decoder? Especially, when these signals are unknown, unclear or just strange. No, we can’t. Decoders must be informed very well, with which material they are going to work. The signal must be prepared at first. The signal must be defined and identified; the parameters of the signal must be gotten before it can be placed in decoder/demodulator. In other words, the signal must be qualitatively analyzed first of all.

In that way, it is clearly obvious that signals analysis take the very important place in lot’s of directions of the radio sphere.

SA allows to realize analysis for everyone who wants it. You can’t be born as an analyst, but you can become the analyst.