Signals Analysis

SA update to version v 6.2.6.5

2012-01-25T11:54:00.000-08:00

SA update to version v 6.2.6.5

Planned update.

In this update, possibility of resample and shift of the signals on fractional values of frequencies is added.

Perhaps more important part of current updating, is the first stage of integration in SA calculator K.

The first stage doesn't mean the high-grade calculator. At this stage, in SA the mainframe of preliminary processing, so-called preprocessing is integrated. The primary goals of this block, gathering of primary parameters of the signal, and preliminary rough processing of this data.

The list from the most probable values "Magic K" which detailed analysis will be spent in the second part of the calculator which integration is planned further will be result of work the pre-processing block.

Nevertheless, even in such, very strongly simplified kind, it is already possible to receive authentic enough values K on some signals.

That is much better, than absolutely nothing.As work with the calculator means some knowledge of main principles of its action, and some specific skills, the article concerning calculator use in practice has been written. Also some separate moments and problems of getting authentic values K ==> Analysis OFDM with CP in SA versions 6.2.6.5 - a pre-processor of calculator K.

As usual, in this version some minor errors found out by users SA are eliminated, and small changes are added in some modules and blocks.

Good luck~

FSK:PakNet - communication of data system (VHF)

2012-01-10T07:49:00.000-08:00

PakNet - communication of data system (VHF)

Mode FM/GFSK, Br 8000

Author: SergUA6

Band Width ~12 kHz

Baud Rate 8000 Hz

ACF 108 and 27 ms

RX mode Source I/Q record

The example of PakNet signal. sent by geka.

Sonograms:

pic.1 General view (two radiochanneles)

pic.2 Manipulation speed

pic.3 Bit stream

Diagrams:

pic.4 108 ms Period in VMW

pic.5 27 ms Period in VMW

pic.6 the signal's ACF

PakNet - One of the oldest systems of documentary communication. It was founded in 1985-86 years.

It is necessary to notice that within these years there was very intensive growth and development of various networks, such as Rosnet, Rospak, Sprint, Paknet etc. From that last abundance up to now days not many of them are still "alive" - PakNet one of the such.

The cable network of Russia concerns documentary networks, to the same category belongs PakNet, which is realized on qualitative another high level, than a cable network.

In general PakNet, is not so much name of the protocol or a signal kind, but the name

of the network.

New article: "GMSK and OQPSK"

2011-11-19T11:45:00.000-08:00

It's a small article, which dealt with the problem of identifying GMSK and OQPSK.
We hope this will be useful...

It's a small fragment...

OQPSK and GMSK are tightly connected, as well as SDPSK and CPFSK, as well as pi/4 DQPSK and C4FM.

Such "dualism" is spread enough, and connected/linked by the fact that often some modes of frequency shift keying at some conditions, smoothly flowing and/or aspire to acquire the shape of phase manipulation.

*** GMSK ***

The general features of GMSK manipulation formation, we had already considered in the article FSK, GFSK, MSK, GMSK and some other modes . Also it was marked, that application of the filter of the Gauss allows to narrow the main spectrum of a signal considerably.

The filter of the Gauss is characterized by parameter BT, interested ones can independently learn this subject, us interested in the practical for the analysis moments.

The value range of parameter BT lies within 1 > BT > 0 limits. The lesser BT value, the more compact spectrum at resultant signal GMSK.

GMSK with the filter of the Gauss with BT = 1, is turning into classical MSK.

For formation of GSM signals the filter of the Gauss with BT = 0.3 is standardly used, and on an example of the synthesized signals it is possible to look as it looks from positions of tasks of the analysis.

Some preliminary remarks.

As, the finished result of concerning of GMSK nuances will be some conclusions about signal TETRAPOL

, then the synthesized signals have the same speed of manipulation equal 8000 Hz.

Besides, sometimes I will add a bit of white noise in the synthesized signals, because ideal signals though look beautifully, nevertheless, having absolute accuracy, in some cases these ideal signals conceal/hide the general details or make these details badly watched. This moment should be well clear from a picture below.

The full description here.

SA update to version v 6.2.6.4: Visualization improvement.

2011-11-06T10:25:00.000-08:00

SA Update to version v 6.2.6.4.

The planned SA update.

The error, which has been found out by users is fixed: At the opening of stereo files with wav tag, which differs from 1 and 3, the program was going into "deep dream".

Also the displayment of the expanded information about the codec, which is applied in a current wav file is added. I specify, that it is not type of codec which the program supports it, it is the codec title, which is used in the current wav file. Sometimes it allows to communicate with suppliers of records/signals more in detail.

Visual displayment of the constellations and transitions in them is increased in phase viewer , at least visually, the new format looks much more attractive than the old.

Also, as always, the number of minor bugs is fixed.

PSK: TETRAPOL

2011-11-05T07:59:00.000-07:00

TETRAPOL

The trunking system for VHF, Br - 8000, mode GMSK

Author: SergUA6

Band Width ~9000-1000 Hz

Baud Rate 8000 Hz

n-Ary (PSK/MPSK) GMSK

ACF 20 ms

RX mode source I/Q record

Perfect by the quality example of TETRAPOL. Sent by foregin collegues.

An example of TETRAPOL (two channeles). Sent by foregin collegues.

Sonograms:

pic.1 General view

pic.2 Manipulation speed

Diagrams:

pic.3 The graphical spectrum

pic.4 Allocation of the channeles

Pictures:

pic. 5 Phase constellation

pic.6 Transitions in the constellation

pic.7 The signal's ACF

TETRAPOL - an old enough system of digital trunking communication/connection, which had gotten wide enough spreading. The standard is developed in the mid-eighties the last century. Usage of GMSK modulation with the shaping/forming filter of the Gauss with BT = 0.25 is very interesting. I Will remind, GSM uses the filter of the Gauss with BT = 0.3 and has compact enough spectrum, reduction of this parameter allows to narrow further the spectrum, but as a whole, it does already noticeably reduce interference immunity or restricts/reduces the zone of confident communication. It Was unexpected enough to find out, that on the signals sent by foreign colleagues BT is even less than 0.25, that even more worses interference immunity.

Nevertheless, in TETRAPOL standard it is marked, that it is possible use both channeles as with band 12.5 kHz (most likely it is with BT = 0.25), so in case of need, with a band 10 kHz, and it already implies smaller BT values.

Considering that the standard isn't oriented on commercial networks, and intended for the organization of communication services of public safety, then some lowering of a confident cover zone isn't serious lack according to the developers opinion.

CROWD-36 (SERDOLIK) - OFDM mode

2011-10-16T16:42:00.000-07:00

CROWD-36(SERDOLIK) - OFDM mode

Ch-34, Br-40, Sh-40, PSK-4, The OFDM without CP

Author: SergUA6

Band Width ~1400 Hz

Baud Rate 40 Hz

n-Ary (PSK/MPSK) PSK-4

Count of Carriers 34

Step between carriers 40 Hz

Pilot tone(s) 393 Hz, this tone or pilot, or continue transmit data of zero in PSK-4 mode

RX mode SSB

The example of CROWD-36 (SERDOLIK) OFDM MODE

Sonograms:

pic.1 General view

pic.2 Manipulation speed

pic.3 Detalization of the second channel

Diagrams:

pic.4 The first channel in the fourth degree

pic.5 Constellation of the first channel

CROWD-36 (SERDOLIK) - OFDM mode - is curious enough signal, where the principles of OFDM technologies usage for formation of a various type of manipulations/modulations are perfectly shown.

MFSK and OFDM segments are generated/formed absolutely equally, the difference is only in the form of used modulation, besides this OFDM signal has no cyclical prefix. Speed of manipulation is precisely equal to frequency space (step between frequencies) - that is the big rarity, and it is possibly linked with the fact, that initial synchronization is provided on the operation stage in MFSK a mode.

The presence of pilot-tone or the continuous transmission of zero in PSK-4 mode is viewed In the second channel of OFDM segment, alghough i can't say definitely.

Though OFDM signals without CP are very difficult for the analysis, in this record it is even possible to define a manipulation mode in the first (lower) channel thus this channel is rather easily possible to select/mark this channel confidently enough, thanking presence of the pilot-tone in the second channel.

Absence of the prefix allows to use as much as possible densely all the spectrum, with the maximum real speed that in this signal makes 34*40*2=2720 bps. If the second channel is really the pilot, then the maximum technical speed is slightly less - 2640 bps.

MFSK: CROWD-36 (SERDOLIK)

2011-10-16T16:21:00.000-07:00

CROWD-36(SERDOLIK)

MFSK-34, Br-40, Sh-40, Ch-34

Author: SergUA6

Band Width ~1400 Hz

Baud Rate 40 Hz

Count of Carriers 34 manipulation frequency

Step between carriers 40 Hz

RX mode SSB

An excellent example of CROWD36 (SERDOLIK) MFSK. Send by Ware.

Sonograms:

pic.1 General view at the different spectrum resolution.

pic.2 Manipulation speed

Diagrams:

pic.3 Allocation and quantity of the frequencies

pic.4 demodulation in SA

CROWD-36(SERDOLIK) MFSK From the different sources, it is used by various diplomatic services of the CIS countries, Russia is defined in general easily enough. Spacing is 40, speed 40, frequencies 34.Alghough it is necessary to manage to count the frequencies, because to do it on the spectrum it not so that easy. ;) The number "36" in the name of the signal is the mystery for me. I haven't ever seen 36 frequencies, so I may suppose that 36 frequencies are very seldom used or quantity of frequencies does not play a role in the name of the signal.
Speed of manipulation in chat-mode makes 10 hertz. Mazielka 2 tone and it is possible Mazielka 6 tones are Very closely connected with Crowd-36.

OFDM, COFDM: DRM+ (DRM-E)

2011-10-07T12:20:00.000-07:00

DRM+ (DRM-E)

Ch - 213, PSK-4, Br - 400 Hz, Sh - 444.4(4) Hz, k = 1/9

Author: SergUA6

Band Width ~95500 Hz

Baud Rate 400 Hz

n-Ary (PSK/MPSK) PSK-4

Count of Carriers 213

Step between carriers 444.4(4) Hz

ACF 100 ms

RX mode Source I/Q record

The excellent example of DRM+. Thanks to IK1YDE.

Sonograms:

pic.1 General view

pic.2 The main signal's parameters.

Diagrams:

pic.3 The constellation in the channel

pic.4 Detalization

Pictures:

pic.5 ACF of the signal.

DRM+(DRM-E) - DRM format for VHF broadcasting, it is intended to extrude the analogue decisions in this sphere. It posseses range of attractive advantages: the necessary band is about 95-96 kHz on the broadcast channel, the transmission till 4 of independed programs is possible in one channel.

The signal itself is the typical representative of OFDM tecnology. All the parameters are defined in SA easyly enough. The maximum technical speed for PSK-4 and 213 channeles is 170 kbit/sec. In reality, the real speed of data transmission is a bit lower (about 130-150 kbit/sec), at the expencse of usage of part of the channels and symbols as the pilot/service.

As far as i know, the prespective of this standard in Russia are *foggy* enough, this record sent by collegues from Europe.

SA update to versionv 6.2.6.3

2011-09-30T12:24:00.000-07:00

SA update to version v 6.2.6.3

This is the planned SA update.

In this version support of Drag-and-Drop function is added.

The function of detection/determinition of the offset modes of the phase manipulation is introduced in the Phase viewer.

It is necessary to show certain care, as any automatic system of identification, this function can be mistaken, especially on the signals, which are damaged by various distortions. Nevertheless in some cases, the presence of this automatization is justified.

Also a number of minor errors found out by users is corrected.

~ Good Luck

Scrambler: Hagelin HC-256, HF

2011-09-24T08:18:00.000-07:00

Hagelin HC-256, HF
Analogue dynamical synchronized scrambler.

Author: SergUA6
Band Width ~3000 Hz
Low Range ~300 Hz
RX mode SSB

The signal is here. Send by Angstrem.

Sonorgam

pic.1

HAGELIN HC-256, HF - the analogue dynamical synchronized scramler. It sounds like "Pinocchio" :-).

The features of this signal: the preamble is the same as two-channeles FSK-2 with the parameters ( look pic.1). There are short synchro-bursts also every ~400 ms (look pic.1).

Update SA to version 6.2.6.0

2011-08-22T13:08:00.000-07:00

Update SA to version 6.2.6.0

This is planned update SA.

Added possibility insert the saved path to the file/directory. This is really handy because sometimes a very long way, and clicking on directories rather tedious, easier to insert from the clipboard.

Added the possibility of fast increase in the desired part of the signal in the WF module. Fragment between V-markers scaled over the entire window.

Function of oversampling uses parallel computing, in general, it increases the speed and quality.

Quality resampling improved by revising the algorithm and its optimization.

The examples old and current solutions.

Extreme caution should be taken with to any external processing program. As minimum all need thorough inspection and testing, otherwise You may experience various unpleasant incidents, such as this one.

SA provides accuracy of 1 Hz resampling at sampling rates up to 100 MHz.

In fact, precision in 1 Hz is not a fundamental limitation, and the internal procedures of SA uses precision oversampling in fractional values SR, if needs.

In the OFDM module, function of "Find CT" also uses parallel computing.

As well as the usual fixed various minor problems.

Good Luck.

OFDM, COFDM: DVB-T (Digital Video Broadcasting — Terrestrial)

2011-08-14T12:47:00.000-07:00

DVB-T (Digital Video Broadcasting — Terrestrial)

Ch-1705, QAM-16, Br~2232, Sh~2790, k=1/4 (not standard/typical mode - 4K)

Author: SergUA6

Band Width ~4800000 Hz

Baud Rate ~2232 Hz

n-Ary (PSK/MPSK) QAM-16

Count of Carriers 1705

Step between carriers ~2790 Hz

RX mode direct output from modulator

The signal is here. Send by horizon.

Sonograms:

pic.1 General view

Diagrams:

pic.2 Quantity of the chanells, manipulation speed

pic.3 Constellation in the channel

pic.4 Constellation in the channel

DVB-T(Digital Video Broadcasting — Terrestrial) - The digital standard of the television, which wide spread all over the world has begun long time ago. In Russia implementation of this standard is carried out since 2004.

This example is received from modulator DVB-MidiMod2 — 2×TS it possesses not absolutely standard parameters. The standard modes for DVB-T modes are 8K and 2K, with a standard band of a signal approximately 7600 kHz. 8K and 2K are the sizes FFT/IFFT blocks, which are used at modulation/demodulation, where K = 1024. In this example the size of the block is not typical for DVB-T - it is equal 4K. 1K, 2K, 4K etc - this are the typified values oriented on usage of the fast algorithms FFT, which hardware implementation is well mastered. Nevertheless, within the limits of coefficient k = 1/4 for this signal, there is a big set of other, absolutely correct sizes of FFT blocks, at which the signal modulation/demodulation is possible, as it is shown. The signal has mass of distinctive features, to enumerate which there is no sense.
Standard DVB-T itself is well documentated and pretty difficult.

From explicit features of this signal, it is possible to mark offset/shift of the central channel of the constellation, what is most likely is a consequence of malfunction of the modulator. At total quantity of channels in 1705, loss of one, certainly isn't a fatal problem as in standard DVB-T powerful noise-resistant coding is used. It is necessary to mark that in 2007, the new standard DVB-T2, which had been accepted, possessing considerably more ample opportunities than DVB-T.

Update SA to the version v 6.2.5.8 : implementing technology of parallel computings

2011-08-02T12:44:00.000-07:00

Update SA to the version v 6.2.5.8

Planned SA update.

At the desire of users, in this version support of 8bit data in unsigned and signed formats is added. The unsigned format is typical for the standard wav files, signed format for the various exterior devices, programs and calculators.

Also, since this version, we are implementing technology of parallel computings. It allows to double, quadruple etc. speed of the main operations, depending on an amount of cores in the processor.

The maximum quantity of CPU cores supported by SA is equal 8, it is not the principle limitation, simply we have considered that it will be enough for beginning , and if composition CPU includes 16 cores or more, SA won't use all of them, but SA will try to involve all accessible cores to 8 inclusively.

On the current moment, the functions of the main working window are already parallelized. The screenshot above, shows:

- Red color - means already parallelized operations
- Green color - means not parallelized operations, but very strongly optimized
- Not selected by any colour - means it is left "as is" yet.

It is the initial stage of increasing of SA computing power, further gradually, we will translate/turn whenever possible, all functions of the program in this parallel mode.

Though this version already had preliminary and careful beta testing, some errors are still possible, which will be corrected in the process of their detection.

Good Luck~

Updating SA to the version v 6.2.5.4.

2011-07-23T05:01:00.000-07:00

Updating SA to the version v 6.2.5.4.

This is planned update SA. We had added function of inversion of the whole spectrum at once. This function, in difference from regular procedure, works much more quickly. Very often similar problems arise at the analysis of various I/Q (SDR) records.

At coincidence/combination of H-markers and a call of the regular procedure of in-band inversion, the special case of fast inversion of the whole spectrum is working.

***
two popular enough in analysis functions ACF and CCF are introduced into module WF. Basically, it duplicates similar decisions in the basic working window, but for the module of the form of a signal, this opportunity is far not superfluous.

Please pay attention, that the result of ACF function is displayed in the new window.

The result of function CCF is mapped in the same window, whence the function has been caused. Thus, the basic signal is mapped as a background, and the working element of the window is function CCF, its graphic is scaled, displaced, etc. the Segment/fragment of a signal, which is chosen as example for calculation CCF, is painted in yellow color.

***
The work with long symbols (up to 32000 samples (LS) and higher) is provided in module OFDM. The previous versions had restriction in 9000-10000 samples. However, it is necessary to notice, that analysis of OFDM signals with such sizes LS (~ 16000-20000 samples), demands certain, sometimes essential expenses of time.

As usual, a number of internal small (sometimes even funny) bugs, which had been found out by users are eliminated. To a category of the "funny bugs", we bringh a recent turn of image CT, in this version all is returned on former positions.:-) actually, both variants are correct. But as, the left part at us has been proved as "good" in one of early SA articles - "work with module OFDM, FFT spectrum", we decided to return to a former format of CT display.

Good Luck ~

OFDM. COFDM: Rohde&Schwarz GN2130 digital voice modem

2011-07-13T11:16:00.000-07:00

Rohde&Schwarz GN2130 digital voice modem

OFDM, Ch - 48, Sh - 56.25, Br - 44.4(4), QAM-16/PSK-4, k = 17/64

Author: SergUA6

Band Width ~ 2700 Hz

Low Range ~ 360 Hz

Baud Rate 44.4(4) Hz

n-Ary (PSK/MPSK) Mixed QAM-16/PSK-4

Count of Carriers 48

Step between carriers 56.25 Hz

ACF Typical ~ 45 ms

RX mode SSB

The record of GN2130 is here.

Sonorgams:

pic.1 General view

Diagrams:

pic.2 General quantity of the channels

pic.3 The constellation in the channel

R&S GN2130 - is the The voice modem, optionaly delivered to HF transceiver XK200 of R&S corporation. It is used for a speech transmission after conversions into a digital form, closing of the data by means of internal cryptoprocessor is possible. In this example, 48 channel OFDM signal is orginized, with standard enough parametres.

Modulation in the channels is mixed QAM-16/PSK-4. Features: it is necessary to mark presence of the auxiliary/pilot-symbols , in every second symbol through every one channel for synchronisation and customisation/fine tuning of the adaptive corrector the special signals are transmitted. Also there is a presence of the preamble with duration about 600 msec. Maximum common technical speed for QAM-16 is ~ 8533 bps.

SA update to the version 6.2.5.3

2011-06-26T10:14:00.000-07:00

SA update to the version v 6.2.5.2/3

Current update though doesn't affect the main SA possibilities, nevertheless solves a range of problems.

The first and bad enough problem, is connected with imaging/mapping of the correlative triangle (CT) in OFDM module. I underline only with imaging.

At the usual revision of the algorithms and their decisions, mathematic had confused us with the news, that the correlative triangle left side can't be good/correct/rightly, as there is no general root at words "rightly" and "left". :-)

The joke had been estimated, but nevertheless, really, at the very early beginning of OFDM module development, an output of image CT on the screen was unrolled/turn on 180 degrees concerning a vertical axis. And the right (good/correct/rightly) side CT has appeared on the monitor as the left side. As it doesn't influence results of operation of the algorithm, the error in display wasn't so noticable and had been existing long time enough.

In this version we recover justice as it doesn't demand any fundamental changes in the main mathematical calculations.

Actually such awkward situation is gross enough error, although it doesn't influence the general results.
***
We remove historically added restrictions on the lower bound of filters in WF module and the general-purpose/universal demodulator. In the current version the general approach to a filtration is reconsidered, and the range of setting of frequency of a cutoff of filters is accepted from 1 to Fd/2 a Hertz.

It allows to solve, in some cases, the analysis tasks more effectively.

***
It is possible to set any, in limits from 1 to 1000 level/step of time gating in VMW module, at the usage of a stroboscopic output of the image, in this version.

It as expands VMW module possibilities to the better side.

***
The error in ISD corrector operation is eliminated, we were informed about this error by users. The corrector incorrectly worked in many cases, it had been connected with update of the algorithm of correction in version 6.2.4.6 the Error was thin enough, and to find it out casually was rather problematic: that once again shows, that users are very attentive and skilled in analysis questions.

In this version, besides bug fixing, speed of ISD corrector operation ISD was increased approximately in one and a half-two time, and its efficiency is raised. Thus as before, the algorithm isn't omnipotent, but it is general-purpose/universal, and it still can be mistaken, but in the majority of practical cases, it is well enough compensates various, not fatal distortions of signals.

***

In all previous versions, attempt to load the files with big size and big sampling rate in VMW module, leaded to an exceptional situation (error). Sampling rate reduction In some cases helps, but in general, it does not solve the problem. In version 6.2.5.3 this moment is corrected.

Record-example the size of record ~ 10 mbytes.

***

Also possibility to synthesize various MFSK signals has been added into OCG programm, al though it doesn't affect SA, nevertheless, we recieved requests to include this function into synthesizer, so we realized it it in version OCG 1.2.1.2 The result of synthesis of signal MFSK-11 is shown below.

As usual, a range of small, hardly noticeable improvings had been done, and some minor problems were solved.

Good Luck~

SECAM - National standard of Russian TV

2011-06-21T13:30:00.000-07:00

Full TV spectrum, with NICAM (digital audio channel)

SECAM - National standard of Russian TV

Author: SergUA6

Band Width ~ 7 mHz

RX mode Source I/Q record

The signal is here. Send by geka. The file size is about 10 Mb.

Sonograms:

pic.1 General view

pic.2 The detalization

pic.3 The graphical spectrum

Diagrams:

pic.4 NICAM - digital channel of sound

Pictures:

pic.5 Channel of the brightness after AM detector in VMW

SECAM - National standard of Russian TV - The television standard of Russia. Standard SECAM is well described in the literature, so there is no special sence to stop on it. The interest represents an additional digital sound channel by technology NICAM, in which modulation PSK-4 (QPSK) is used. This additional channel, is allocated apparently from screenshots, between chrominance subcarriers and the main analog channel of the soundtrack.

SA update to version v 6.2.5.0/1

2011-06-15T14:53:00.000-07:00

SA update to version v 6.2.5.0/1

Planned SA update.

Determination of an exact amount of frequencies in the various MFSK signals is an important enough task in the analysis. In this update we had added this possibility, we introduced function "Count freqs” into the module of viewer of the form(WF).

The function "Count freqs" calculations of the size of the grid of frequencies. I underline, not an amount of frequencies used/involved in a current fragment of a signal, but dimensionality of the grid, in which limits these frequencies are generated.

Basic actions on function "Count freqs" usage are the following:

1. To receive speed of manipulation of the signal - Baud rate, by any method. It is desirable, but not a mandatory step.

2. To select the signal by H-markers. This operation demands an accuracy. It is impossible to select the signal too densely, and it is impossible to select it too widely, the reasonable compromise is required. Normally we recommend to allocate the markers on distance within (1.5-3) *Br from the signal.

3. Call the Phase detector function. It is the standard operation, which creates the new window with results.

4. It is necessary to call WF module in the new window through PopUp menu, it is also the standard action. If in the first point value Baud rate has been received, in WF module, then the automatic filtration of the signal will be produced, otherwise the filtration will be necessary to realize in the manual mode.

5. It is necessary that all artifacts (usually it is the beginning and the end of a signal) have been displayed behind the display window in WF module. It is possible to reach, at least by two methods:
The first - to select a pure part of the signal with V-markers, and to create a copy in the new window.
The second - using horizontal zoom, and shifting/moving the signal by the horizontal slider, to bring in the artefacts behind the window borders.

6. To turn on the mapping of the histogram "Sum"=ON on the "pure" signal. To pick up the size of the histogram by vertical. To install H-markers on the upper and lower channel of the histogram. To cause PopUp menu of the module. Position of V-markers can be any as all visible part of the signal is processed.

7. To select point "Count freqs".

Important! The result of function "Count freqs" is not an amount of channels in the signal, but the size of the uniform/proportional grid of frequencies, in which the used channels are "laid down". The so-called grid of formation, the size of this grid represents big interest in the analysis.

Range of determination of dimensionality of the grid of frequencies by the function "Count freqs", is from 4 to approximately 260. In reality, the function defines grids of more dimensionalities to 300-320, but it very strongly depends on the signal quality, and many other things.

Error report appearance is possible.

The reasons/causes:

- Both H-markers, and-or one of them, are installed not on the histogram lines/channels
- There are lesser then 4 or more then 400 frequencies in the signal
- The distance between H-markers is too small, or the markers are combined
- the function can't be completed correctly at current parameters of the signal, or on the current fragment of the signal.

There is an article on usage of this new function, as there are some thin moments and nuances, which are beyond the update description => Signals Analysis in SA version v 6.2.5.1

It is necessary to show certain care, although function "Count freqs" works reliably enough in many cases, nevertheless, it is rigid enough algorithm which can be mistaken.

As usual, minor problems found out by users are removed. Also I want to express gratitude to all beta testers, who have taken part in preliminary testing of this update.

Good Luck~

SA update to version 6.2.4.8

2011-05-23T10:47:00.000-07:00

SA Update to version 6.2.4.8.

This is the planned update.

In this version we are expanded number of SA tools by adding "In-band signal inverse" function.

This function provides qualitative enough inversion of the selected band of a signal or the whole signal, without affecting the other spectrum. It is required for the fast inversion of the signal, and as allows to restore/compensate or reduce various distortions in some cases.

Example of operation with the distorted signal Icom UT-109

Distorted fragment.
Restored fragment.

Also range of minor bugs detected by users had been removed, some small corrections had been added.

Good luck!

Purple License.

2011-05-13T13:19:00.000-07:00

Greetings!

Dear readers and SA users, we would like to inform you, that we have added new type of SA license - it is Purple License.

Often there is a necessity to acquire/get 7-12-15 or more SA licenses, for example for some educational institution or computer classes. For such cases we have added one more type of the license - Purple license. This license has no fixed amount of keys by default, the amount of keys should be specified and paid by user. The amount should not be less than 5 keys. We are hope, that this type of license will help to solve some questions concerning SA acquisition.

New Article: Perspectives of the analysis of OFDM signals with CP.

2011-05-03T15:45:00.000-07:00

Perspectives of the analysis of OFDM signals with CP.

As usual, we assume that reader possesses some basic knowledge concerning principles of formation OFDM, and the reader is acquainted with our previous articles, as terminology and the main ideas remain former.

There are some general provisions.

We already were being considered and showed in the previous articles, that at formation of OFDM signals the basic/main/key parameters are LS, LU and LG (CP), which are having dimensional samples. Basically, each one of these two parameters from these three (LS LU LG), unambiguously set the third parameter, as there is a simple correlation, namely:

LS = LU + LG;

We add one more, the dimensionless parameter, coefficient k = LG/LU or k = ((Sh/Br) - 1). This parameter allows to receive correct LS, LU and LG for specific conditions, besides k possesses mass of other remarkable properties, but it is beyond this article.

In a general view the scheme of formation of OFDM signal with CP looks as follows:

As we already considered, and I once again underline this moment, that there is no any Hertz and-or seconds! LS, LU and LG have at a stage of formation dimensionality of samples/samplings. We name it Fundamental/primary/key parameters of OFDM signal, these parameters are core of OFDM signal. All is equal to these parameters (samples), with what speed they will be transferred, needless to say, that transmission/transfer speed should be a constant.

As soon as some speed of following is given to samples (sampling rate of formation of OFDM signal OFDM), then earlier faceless values LS, LU and LG acquire/get dimensionality in Hertzs and-or seconds. But! They don't lose, and can't lose their main/fundamental properties. For example, as there was duration LS = 100, LU = 60 and LG (CP) = 40 samples, so it remains, irrespective of sampling rate.

There is one nuance in these transparent and logical enough conclusions. All what has been told above, concerns to so-called sampling rate of formation of OFDM signal.

In practice, to form a signal at once on operational frequency it is not convenient, and frequently it is not even possible. Normally, the signal should be formed on sampling rate Х, and further whole spectrum of the signal should be transferred on operational frequency Y. Thus, sampling rate X can't change duration LS, LU and LG, as it (sampling rate) is a consequence of existence of these parameters, and frequency of transfer Y can't destructively influence these parameters as it is not connected to them.

Let's sum up the told...

Full version of this article you may read here.

The arcitle contain examples on the real signals, schemes, detailed pictures, explanations and other interesting information.

OFDM, COFDM: CIS-79, conditionaly name TANDEME

2011-04-29T18:26:00.000-07:00

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

2011-04-15T08:11:00.000-07:00

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!

Update SA to version 6.2.4.4

2011-03-23T14:06:00.000-07:00

SA update to the version v 6.2.4.4

We continue to increase SA power and abilities, we expand possibilities of OFDM module of the analyzer in this update.

1. In display of OFDM signal spectrum small pedestal/platform in 10 pixels is added. It allows to see all line of channels current/investigated LU.

2. Possibility to display on phase planes only every second, the third etc. symbols is added.

3. Possibility to shift/replace a start point is added during dynamic mapping. In a combination with the previous element, it allows to find out/study rather effectively various special channels/symbols in signals.

As an example there is one service channel of signal WinDrm is shown below.

For comparing it is shown as it looks/looked in old versions.

Important! The second and third points of updates, work only in a dynamic mode!

This update considerably expands analysis OFDM signals, bringing it on qualitatively higher level.

Small manual on the technician of OFDM analysis by means of current version SA are described in the article the Overview article (manual) about the analysis of various OFDM signals in SA versions v 6.2.4.4

Good luck.

Examples of using MFSK demodulator in SA v 6.2.4.2

2011-03-04T10:59:00.000-08:00

Examples of using MFSK demodulator in SA v 6.2.4.2

In this article, we will consider examples of usage of universal MFSK demodulator in SA version v 6.2.4.2

Practically, any FSK/MFSK signal can be demodulated to a bit-stream in SA last versions. Here is, when we say "any" we mean, that there is nothing known about a signal initially. Also it is meant that necessity for obtaining/getting of the bit-stream can arise at any moment, on any signal, or any part of a signal.

The Example. The record of an unknown system in a VHW band ~900 mHz.

Step by step guide of main actions is shown below:

Step 1. Select a necessary/interesting fragment of the signal and create a copy.

Step 2. Select a necessary/interesting band of the signal and move it in a bottom.

Step 3. The Main objective of the previous step is the reduction of sampling rate to an optimal value. Initial record has sampling rate 68 mHz, and it has sampling rate for the signal, which is interesting us with the full spectrum in ~ 180-190 kHz is absolutely superfluous.

The mechanism of the abstract frequency conversion of sampling rate is built in SA, that is to us it doesn't matter which sampling rate will be specific, it is important that it would be optimal. It works as follows, and we had already wrote about it in one of updates.

In the same way works the abstract shift of a signal by frequency. It is also doesn't matter to us which position the signal occupies, but it is important that it would be in optimal position by frequency on sonogram.

Let’s come back to the signal.

The full version of this guide-article you may read here.

Update SA to the version v 6.2.4.2

2011-02-28T23:28:00.000-08:00

Update SA to the version v 6.2.4.2

In this update the range of problems found out by users has been solved.

1. The rigid/hard restriction on data size for calculation ACF and CCF is introduced.

The matter is that due various reasons, at the call of ACF and CCF functions SA user can casually push "Ok" in a situation, when the user hadn't supposed to do it, or the user wanted to push "Cancel" instead "Ok", and the hand itself has pushed other button. :)

In this version such situations are eliminated. The maximum data size for operation of function ACF makes 70 mbytes. For CCF, the maximum size of a fragment is about 50 mbytes. If these restrictions for someone are essential, please inform us about it (e-mail us), and we will solve this question.

2. Very often, after the phase detector, the call of signals waveform module follows. In this version, if beforehand the value of clock frequency has been recieved by SA tools, then LPF filter is applied at once by default. Normally, in 99 % of cases, this is the standard action, which is just automated now.

As usual, except the described changes, a range of hardly noticeable, but important moments is fixed.

Good Luck!

SA update to version v 6.2.3.8: Universal MFSK demodulator

2011-02-20T07:39:00.001-08:00

SA update to version v 6.2.3.8

In this update, the pilot version of the general-purpose/universal demodulator MFSK is realized.

The demodulator supports to 256 levels (frequencies) of various MFSK signals. As an example: obtaining of a bit stream from the records Packet AX.25 and APCO-25 it is shown on the picture above. As FSK-2 it is special case of MFSK, the current extension of the module doesn't influence the previous possibilities, but only expands them.

Please pay attention on the allocation of levels of demodulation. The first and last levels, aren't restricted by the markers! Their area is stretched behind their limits, as it is shown below.

The bit stream can be presented in two variants.

The first variant is the symbol representation of levels recoded by default. In this case, the internal map of codings is used. 32 characters are supported standardly. It is favourable for using for FSK-2, MFSK-4,8,16 etc., that is, for rather few-channeled MFSK modes.

The second - obtaining/recieveing of the stream in the form of HEX-byte. Bytes in this case are partitioned/devided by the symbol-separator "x" (the Latin character "X" on the lower register).

As, the bit stream implies further processing anyway, we have refused an inverse mode. There is no big sense in an inverse mode, as an inverse can be received in any exterior viewer. Besides, we are planning to create our own special viewer of a bit streams.

Below you may view the practical example of operation of general-purpose/universal MFSK demodulator on the signal South African Navy.

Good luck!

OFDM, COFDM: CIS-128

2011-02-15T10:51:00.001-08:00

CIS-128

Br~21, Sh~23.5, Ch-128 in use, total 129 - 1 as gap/off/skiped

OFDM, COFDM

An example of CIS-128 signal is here

Author: SergUA6

Band Width ~3000-3100 Hz

Low Range 470-500 Hz

Baud Rate ~21 Hz

n-Ary (PSK/MPSK) Mixed mode QAM-16 and PSK

Count of Carriers 129 - 1

Step between carriers ~23.5 Hz

ACF ~476-477 ms

RX mode SSB

Sonograms:

pic.1 General view

pic.2 Clock frequency of manipulation (classical method of recieveing)

Diagrams:

pic.3 The signal's detalization in OFDM module

pic.4 Detalization of the signal if OFDM module

pic.5 Detalization of the signal if OFDM module

Pictures:

pic.6 ACF of the signal

pic.7 CCF of two adjacent fragments with duration 250 ms

CIS-128 - is an interesting enough signal, though quality of the record is not so high. Nevertheless, rather easily it is possible to receive all main parameters in module OFDM. It is shown on the pictures.

It is very interesting that there is divergence ACF with a real state of affairs. ACF shows that there is a periodicity in 10 symbols in the signal. The detailed analysis in module OFDM allows to find out that every fifth symbol is specia l(synchro), and it is logical to expect, that ACF will be with the same period, but it is not so. This moment is easily specified with usage of CCF function. As it is shown on rice 7.

It is well visible that every fifth symbol special (synchro), but special (synchro) symbols different, and alternate through one. It also shows ACF as in this case the repetition period is really equal to 10 symbols.

CCF allows to receive more fine and exact structure, where it is displayed both the general period of special (synchro) symbols, which is equal 5 symbols (steps), and the period of separately even and odd symbols, which is equal already to 10 steps.

One more feature of this record which is well visible in dynamics - is the intensive use of modulation QAM-16 in the first half of the signal, and episodical/rare in the second part of the signal.

SA update to version v 6.2.3.6

2011-02-12T05:24:00.001-08:00

SA update to version v 6.2.3.6

We have added a cross-correlation function (Cross-Correlation Funсtion- CCF) in this update.

In a difference from ACF, CCF function, in some cases, can provide more information about a signal or the selected fragment.

After CCF launching, the cross correlation of the selected fragment of a signal between V-markers and whole record is calculated. It is shown typical on the picture, and it is certainly far not just one example of CCF usage.

As it is not difficult to notice, the selected fragment, enters as a component into all units of the signal on the record, and the position of this part is precisely defined on peaks of CCF resmult. The maximum peak will correspond to position of an initial fragment, as correlation in this case is 100 %. It is problematic enough to find out this singularity by other methods.

As usual, some bugs, which has been found out by users are eliminated, a range of internal functional improvings is realized.

Good luck.

Updating SA to the version v 6.2.3.4

2011-01-13T15:59:00.000-08:00

Updating SA to the version v 6.2.3.4

Users find out two problems.

The first problem. Sometimes, at the call of WF viewer, in the opened window, the part of a nonexistent fragment of the signal is displayed, usually, in the end.

The second. After registration is done. At the start of already registered version, the registration window keep constantly appear at each program opening.

Both problems were being happen rare enough. The last problem, in general, had been found out only in one case.

Nevertheless, if the user will be sending the detailed, step-by-step mechanism of occurrence/occurrence of the problem, chances of the fast and successful decision are rather great.

In this update we have removed these two errors, and we have added the new abilty into SA palette of tools.

The ability to obtain/get the first derivative of any signal, which is loaded in SA, have being added. The competent combination of this possibility with other tools, in some cases, expands the analysis, allowing to receive considerably better results.

There is the example on the picture, which shows an application of the first derivative, for obtaining more accurate and clear ACF picture, after quadrature detector.

The first derivative in DSP, at the general case/image, is approximated well enough by a difference of the adjacent samples of the signal.

As a whole, the first derivative can be interpreted as UPF with the special characteristic. Repeated application of this function is equivalent to obtaining of high-order derivative. I have to notice, that in practice it is extremely rare occurences, as already the first derivative received by method of multiply function application, in strict mathematical sense is not fully correct.

The signal-envelope sometimes is very informative by itself, but presence of a constant component frequently masks/hides various features. Using of the first derivative of the signal's envelope as the material for analysis, can strongly help in such cases. As it is shown on the example.

Good Luck~

SA update to version v 6.2.3.3 : OFDM Module.

2010-12-29T12:00:00.000-08:00

SA update to version v 6.2.3.3

Long enough time ago SA users SA had paid attention that the copy of the selected on the sonogram fragment visually looks shorter than the original. This interesting phenomenon, entirely linked with property of uncertainty of FFT transformation.

The matter is that transition from the time area into the frequency area, which provides FFT transformation, excludes possibility of exact definition of position of concrete frequency component by the time. FFT only "says" that the component is entering into the block, but where is the component located in the block is unknown.

It is the very old and standard problem. It has no exact decision, but we counted possible to lower a sharpness of this phenomenon. As the basic problems arise within the small blocks, when the resolution on time on

the sonograms is rather good.

This is realized in the current version.

We just make replacement of one problem by another. If in the old versions, copied by the sonogram fragment, physically had such duration which had been displayed at the moment of copying. That in the current version, the physical duration is longer than it is specified at copying.

We have considered possible to go on such exchange, for two reasons.

In the first, users confuses that the copied fragment visually looks shorter, and this situation demanded actions to regulate it.

In the second, the work on the sonogram, assumes visual perception, and it is better to see the copied fragment the way it has been selected, neglecting real accuracy. Even more so further it is necessary to work with the fragments in the area of the sonograms displaying.

The mode of a signal review has been added by the users offer.

The review is provided by FFT window with the size in 1024 counts. The primary goal of the mode it is to pass part of the signal with preamble or another problem segment (by having placed the start point in the necessary position), before the correlation triangle search will begin.

In the review mode, FFT window moves on the signal loaded in OFDM module, by the slider which is shown on the picture.

After key parameters of the signal are gotten, it is possible to define the detailed parameters of the preamble or other fragmen, by moving symbol-by-symbol backwards on the part passed earlier.

The detailed example on the real signal is described in the article OFDM analysis in SA version 6.2.3.3

Also the problems concerned users bug reports are removed.

Using SA to measure and correct sound card digitizer errors.

2010-12-18T08:04:00.000-08:00

Using SA to measure and correct sound card digitizer errors.

This article had been written completely on the basis of letters sent by SA users.

All sound cards and A/D converters have some clock error. This is especially true if converters are commercial and cheap ones, like PC sound cards and similar. Professional and expensive converters exhibit a much better clock stability and jitter.

To correct this error, one must know nominal parameters of the signal under test. If these parameters are known, it is quite easy to correct digitizing clock error using SA.

The SA method of “Correction of BR” is quite good for this job, but perhaps using resampler as data input is a better procedure.

The correction factor will have to be measured for any digitizing speed and mode.
Bear in mind that for cheap cards, the speed can vary due to various factors, so if high precission measurements are required, a new calculus should be carried out.

For a good measurement, a quite big signal is needed.

This method is useful for PSK,FSK,MFSK and other modulations. To use it with OFDM, some more operations should be carried out using SA.

Ideally, an external signal like GPS 1000 Hz or a signal from a high end signal generator will provide the best results. Also, a radio timing signal should be good enough.

The best way to understand the subject is an example.
A well known signal as Stanag-4285 (sampled at 8000 sps) will be used to show the method.

We know 4285 has a nominal speed of 2400 sps. Since a frame is 256 symbols, the frame time must be 106,666666 mS. This is the value that should be obtained if using the VMW feature of SA when signal structure is perfectly vertical.

As we can see, the mesured value is 106,69241.

Correction factor =measured value/nominal value=106,69241/106,66666= 1,000241
Error PPM=(correction factor-1)* 1000000= (1,000241-1)*1000000= 241 PPM.

Real Digitizing speed= 8000*1,000241 = 8001,931
Real modulation speed (Br) = 2400/1,000241 = 2399,421739

Measured SA Br= 2399,41

Now, lets go to correct the signal using calculated BR in SA.

The signal parameters are almost perfect, so we can save it and after this procedure, we can be quite sure the new signal will be demodulated using any comercial demodulator.

Also, we know the correction factor for the used card in that speed.

As soon as parameters of a sound card in the record channel are received, then it is possible to realize precise measurements of replay( reproduction) channel for sound cards, which have separate record/reproduction channeles.

You can perform these measuremens simply by having connected an output of such card with an input, playingback a known/synthesized signal/file. Measurements should be realized by the technique described above. As the error of the channel of record is already known, it can be easily considered, and there will be only an error of the channel of reproduction/replay/playback.

PSK: CIS-3000

2010-12-12T13:31:00.000-08:00

CIS-3000

PSK-8, Br-3000.

PSK

The record of this signal is here. Send by RadioKoteg.

Author: SergUA6

Band Width ~3400 Hz

Low Range ~600 Hz, in this example only!

Baud Rate 3000 Hz

n-Ary (PSK/MPSK) PSK-8

Carrier frequency ~2313 Hz, in this example only!

ACF Preamble ~ 85 ms

RX mode SSB

Sonograms

pic.1 Generall view

pic.2 General structure of the signal

Diagrams:

pic.3 8th harmonic

Pictures:

pic. 4 Phase constellation

pic.5 ACF preambles

CIS-3000 - With very high probability this signal has the Russian origin roots. More and more often there are signals which are leaving the limits of standard phone channel. This signal represents that kind of signals. The spectrum of this signal occupies 3400 Hertz. The maximum technical speed 3*3000 = 9000 bps.

SA update to version 6.2.3.0

2010-12-04T15:17:00.000-08:00

SA Update to version 6.2.3.0.

Changes has been added in OFDM module operation.

Algorithm of search of a correlative triangle has been also changed. Current implementation of this algorithm successfully enough copes with the short signals.

Function of obtaining of exact value of clock frequency is updated. Now besides obtaining of the clock frequency, the task of obtaining of an optimal position of the signal by frequency is solving. It does automatically translates the triangle in the necessary positive polarity. All that demands some time, so no need to be nervous:-)

Some pauses (till 3-5 seconds) in operation of "Get Br" function are possible, The pauses depend on many factors:

from sampling rate of a signal

from its position on frequency

from the sizes LS and LG etc.

In generall, the program solves wide enough range of tasks in an automatic mode. From the user it is required only to situate the triangle in "a good" position and to call function "Get Br", and it is not important if there will be the positive triangle or negative, the program itself will translate the triangle into the necessary type, through search of optimal shift by frequency.

It is necessary to note that shift by frequency isn't precise because precision isn't necessary, while it is very close to optimal value, from the point of view of the program certainly.

All these changes and additions are preliminary preparation of the module for the decision of the primary task: obtaining LS and LG values of concrete signal, within the limits of our ideas, which were described in the article Parameters of OFDM signals.

Some minor problems had been found out by users and solved by us.

The more detailed information of operation with OFDM signals in version 6.2.3.0 will be described in separate article.

Good luck!

MFSK: WinMor

2010-11-28T15:26:00.000-08:00

WinMor, mode 2*MFSK-4

Amateur's mode. Br - 46.875

Here is the record of the signal. Send by JenyaT.

Author: SergUA6

Band Width ~500 Hz

Baud Rate 46.875 Hz

Count of Carriers 4 in one group and 4 in second group

Step between carriers 46.875 in group, 93.75 between groups Hz

RX mode SSB

Sonograms:

pic.1 General view

pic.2 Detaltization. Two groups of MFSK-4

pic.3 Detalization of the groups. Space between the groups.

Diagrams:

pic. 4 Start

pic.5 Start detalization

Pictures:

pic.6 Graphic spectrum of the signal

WinMor, mode 2*MFSK-4 - it is the new amateure mode (atleast it is announced in 2010 year), which had been created by radio amateurs. The protocol has a lot of transmission formats. In the current example of the signal, two MFSK-4 channeles are used. The signal is bright enough, so there shouldn't be problems with it's identification.

SA update to version 6.2.2.8

2010-11-17T13:13:00.000-08:00

SA update to version v 6.2.2.8

This is planned updating.

The new element in the general options is added.

Internal management of markers is reconsidered. Appearance and the size of the markers has been changed.

It is problematic enough to surely catch the markers by mouse with the thickness in 3 pixels, on the big monitors. Although it is required not so often, it may cause some inconveniences.

Correct independent work of two and more Phase Plane modules is realized. Some users actively use this possibility, and in old versions it worked not correctly.

We also prepeared the demo clip, which shows how to work with the bottom panel of tools. In this clip, we finish the review of the basic SA working window, and in The further we will countine to make demo clips about work with concrete modules.

All demo clips are recommended to be started on monitors with the permission not less then 1024х768 in mode Normal size 96 DPI.

The list of demo files of own SA format are located in special section of the site => Video examples on use SA.

Good Luck.

SATCOM Satellite, US INTEL - 260.41, UHF (B)PSK-2, Br - 260.41

2010-11-06T09:34:00.001-07:00

SATCOM Satellite, US INTEL - 260.41, UHF

(B)PSK-2, Br - 260.41

Here is the signal. Send by RSCAN.

Author: SergUA6

Band Width ~520 Hz

Baud Rate 260.47 Hz in this example, exact value 260.41

n-Ary (PSK/MPSK) (B)PSK-2

ACF ~1900 ms preamble, ~368 ms data/message

RX mode SSB

Sonograms:

pic.1 General view

Diagrams:

pic.2 General structure of the signal

pic.3 Phase constellation

Illustrations:

pic.4 ACF

SATCOM Satellite, US INTEL - 260.41, UHF - is the very wide spread signal, which can be met in the channeles of satellite group SATCOM. This signal is encrypted.

SA update to version 6.2.2.5

2010-10-29T14:05:00.000-07:00

SA update to version 6.2.2.5

Automatic synchronization of phase added in FSK-2 dem module.

The presence of two degrees of adjustment (in phase and frequency) for setting/selecting accurate clock for many presents certain difficulties. As miminum the phase synchronization can be achieved fairly quickly and qualitatively, in automatic mode.

This is implemented in the current update.

If the automatic phase is ON(enabled by default) setting the exact value of the clock frequency is greatly simplified. In addition, in most cases, automation will work better and error free.

Nevertheless, the possibility of a transition to a fully manual mode is preserved, sometimes it's necessary.

Automation mode helps to significantly over short and very short signal/fragments.

Algorithm for automatic phasing is not sensitive to the long series of zeros or ones at the beginning of the fragment, it usually is the problem seriously. This situation handled correctly, however, should not take very long series. Also not recommended to take when copying or selection, start part of signal with noise, this can completely disrupt the work of the algorithm.

Although algorithm was developed an for signals FSK-2, he copes with C4FM, which greatly facilitates the identification of this regime and etc.

In general, the automatic phase synchronization, when set properly of clock frequency. Guarantees a correct bitstream and greatly simplifies the module FSK-2 demodulator in SA.

Generally, issues guarantees the correctness of the bitstream is a separate issue, which many prefer to sidestep/not see. :-)

Good Luck!

SA update to version 6.2.2.4

2010-10-23T10:33:00.000-07:00

SA update to version 6.2.2.4

Under a 64-bit OS (Vista, W7) are errors in the previous version.

The current version of SA 6.2.2.4 passed rigorous testing, all identified problems are eliminated. This version very stable and sustainable for both 32-bit OS, and 64-bit.

Good Luck.

Update SA to version 6.2.2.0/1

2010-10-19T11:10:00.000-07:00

Update SA to version 6.2.2.0/1

In this version added the ability to copy the various fragments of the signal from WF module.

Copy fragments signal from the sonograms, can not operate sufficiently exactly. This is not a problems of SA, it is a fundamental limitation FFT.

The fact that the FFT, in general case , makes a transition from time domain into the frequency domain, and such a thing as time loses its meaning. Within the FFT block does not have time, and to say exactly where in that block is one or another component of the spectrum is impossible. This leads to the fact that selecting/separating out a segment of the signal at the sonograms, there is always uncertainty within the block FFT. Sometimes this quantity is large enough. Hundreds of milliseconds or few seconds and more, depending on size of block FFT.

Copying a fragments of the signals as waveform is much more accurate, but has own problems. Impossible to say exactly, from the image of waveform, exist/included a some frequency components in the selected segment or no.

Although the selection of segments from by waveform and is much more accurate, nevertheless, also not an accurate method. Accuracy is limited to one or two samples. In general, the problem is really accurate measurements and actions, is surprisingly/unexpectedly deep and multifaceted task.

Also introduce the possibility of transferring a fragment of the signal directly in the FSK-2 dem, and solves the problem of obtaining "clean" bit stream, in many difficult cases.

A small example of obtaining a "pure" bit stream from the rather complicated to demodulate the signal.

As usual, apart from updates, fixed bugs found by users. And including minor corrections to improve the work of the various modules and the whole program.

Good Luck!

Update SA to version 6.2.1.8

2010-10-12T03:00:00.000-07:00

Update SA to version 6.2.1.8

In this version, we fixed an error in the function of BRC (Baud Rate Correction) discovered by users, and introduce/added a two modifications.

The first.

Sometimes, it is easier to work with a relative or even abstract concepts, because no matter the specific values, but important that they fit into a certain framework. This applies to the oversampling and shifting of signal by frequency.

Usually, it is required that a signal was in the middle of the spectrum, and the sampling frequency was not much excess.

In this version You can select the frequency shift or frequency oversampling, just selecting the desired point from the list. In some cases, it greatly reduces the time and effort. Possibility of manual input for precise actions, of course, also saved.

The second

VMW module can potentially provide extremely high accuracy, at the request of Spanish colleagues, we insert in the current update stroboscopic method of measurements.

The idea is that, if the data in the record is sufficient, You can get very precise parameters of the signals.

However, there are problems, large amounts of data require very large computing and time.

Given the characteristics of the module VMW, we just calculate and to display every 1 st, 2 nd, 4 th etc lines/rows in the visualization VMW. For all the simplicity and elegance of this method, it provides exellent/perfectly accuracy of measurement.

This is one of the realizations of the stroboscopic measurement method. And like all such methods, it provides increased accuracy with increasing period gating, in this case by rows.

In the screenshot above, perfectly clear that the old method to accurately measure the period of the sine (exactly 1000 Hz) is extremely difficult, error of 20 nanoseconds is not noticeable. In really, an error and in 100 nanoseconds is very difficult to visually detect the slope of the lines is enough small.

A new method for gating each 1024 lines, clearly and accurately detect the difference in a nanosecond! Actually the accuracy is increased compared with the first/old method in 1024 times.

Need to be cautious, as stroboscopic methods for periodic signals may give a false and sometimes very misleading results, due to skip of parts of signal. To prevent this, you should always start measuring without gating. And gradually increasing the accuracy to measurement via of gating.

Good Luck!

SA Update to version v 6.2.1.6

2010-10-05T12:45:00.000-07:00

SA Update to version v 6.2.1.6

In this version speed of calculations, at search of a correlative triangle in OFDM module, is increased non less then 30%.

The algorithm of resampling of records is completely reconsidered.

Earlier we marked, that resampling algorithm in SA though provides precision accuracy on sampling rate, nevertheless distorts Amplitude frequency characteristic/Phase frequency characteristic (AFC/PFC) of signals. Though, it does not have the great importance in overwhelming majority of cases, as distortions affect the upper part of a spectrum. But the problem exists, we knew about it, and we promised whenever possible to solve it.

The problem is most brightly shown at resampling of OFDM signals, as OFDM signals are very sensitive to this sort of distortions.

In current version 6.2.1.6, resampling function works practically with absolute accuracy, in reasonable limits of course.

It is most easier to show the difference on the sonograms.

An old algorithm: there are distortions AFC/PFC on the upper channels of OFDM signal, which are visible even on sonogram.

New algorithm: there are no distortions.

An old algorithm: resampling of the record with sampling rate 68 mHz, on 60 mHz. As anti-alias filters aren't used, manual pre-processing is demanded, for removal of unnecessary components of the spectrum.

New algorithm: an excellent quality. Anti-alias filters are used by default. Although it isn't the main criteria of qualitative resampling, nevertheless it strongly simplifies operation with resampling function , excepting manual pre-processing.

Also the minor bug, which were found out by our users are solved.

Good luck!

FSK: "Avaris" - domestic(Russia) system of special communication on VHF

2010-09-27T08:26:00.000-07:00

"Avaris" - special-radio service(VHF), FM-GFSK, Br-9600.

Author: SergUA6

Band Width ~12000 Hz

Baud Rate 9600 Hz

RX mode Source I/Q record

The record of fragment of work of "Avaris" system.

Sonograms:

pic.1 General view

Diagrams:

pic.2 Signals demodulation

Pictures:

pic.3 General structure of the signal

"Avaris" - domestic(Russia) system of special communication. In a basis of this system, lies using of special repeaters under similar mark "Avaris". Repeaters provide expect the basic functions, also functions of recording coded/encrypted speech messages and their subsequent transfer to concrete addressees or group of users. In this system, and not only in this, speech is digitized by means of the delta modulation. The received digital stream is ciphered and transferred, in this case, GFSK modulation is used.

SA Update: RRC filter is added.

2010-09-22T11:53:00.000-07:00

SA update to version 6.2.1.4

Three new elements are added:

1.In the module of form viewer: median filter had been replaced by new RRC filter. By default alpha = 0.5

2.RRC filter is also added in the module of FSK-2 demodulator.Alpha=0.5 by default. If RRC filter is in OFF state, then the filter, which is analogous to the main filter, works in the signal's form viewer module.

3. The following elements are added in the module of FSK-2 demodulator:

1) elements of image vertical scaling

2) an indicator of filtration process

3) the buttons of filtration start and back into initial state.

4) the cutoff range(frequency) in RRC filter can be specified from 5 Hz to Fd/2 Hz. where Hd is sampling rate. In usual(special, soft) filter cutoff range can be specified only from 30Hz to Fd/3, in the force of realization specifications.

Special attention is focused on saving of signal's fase before filtration and after filtration. The phase do not change

guaranteed.

Also some minor bugs, which had been found by users, are correct.

MFSK: NEXEDGE

2010-09-18T14:11:00.000-07:00

NEXEDGE

NXDN - 4800, 2400. C4FM, BW ~ 10000 Hz, 5000 Hz

1. an example of NXDN with manipulation speed 4800, sendby Rulez Reloaded

2. an example of NXDN with manipulation speed 2400, send by Rulez Reloaded

Author: SergUA6

Band Width ~10000 or 5000 Hz

Baud Rate 4800 or 2400 Hz

n-Ary (PSK/MPSK) C4FM

Count of Carriers 4

ACF ~ 80, ~ 40 ms

RX mode Source IF record

Sonograms:

pic.1 General veiw NXDN with speed 4800

pic.2 Generalview NXDN with speed 2400

Diagrams:

pic.3 Manipulation speed 4800

pic.4 Manipulation speed 2400

Pictures:

pic.5 Sub-optimum demodulation 4800

pic.6 Sub-optimum demodulation 2400

pic.7 ACF NXDN in 2400 mode, only 80 ms

NEXEDGE - is the communication system using NXDN protocol. NXDN is the joint development Kenwood and ICOM companies. The protocol is declared as opened one, modulation which is used on VHF, is the classical C4FM. The Same type of modulation is also used in the other

known communication system APCO-25 on the basis of standard P-25.

On it similarity comes to an end, P-25 and NXDN are incompatible.

As a whole, the signal is easily identified, especially in SA last versions: there are special possibilities, for confident enough identification C4FM. Two variants of the signal are prepresented on the records: broadband, under the standard channel by a strip/band 12.5 kHz, and narrow-band under the channel 6.25 Khz. The maximum technical speed accordingly in a broadband mode 9600 bps, in narrow-band 4800 bps. Thus clock frequency of manipulation for C4FM turns out twice less, 4800 Hz and 2400 Hz.

SA update to version v 6.2.1.2: An output from discriminator and program processing.

2010-09-15T11:40:00.000-07:00

SA update to version v 6.2.1.2

Two new elements are added.

The double half-wave detector, and the module of FSK-2 demodulator.

The double half-wave detector, generally, has narrow enought area of application, and as a whole, it strongly loses to the quadrature detector. However, has a high processing speed, and in some cases, it allows to solve problems of reception of clock frequency of manipulation, while other methods work very poorly or don't work absolutely.

Usually, the problems with reception of clock frequency of manipulation occur, when the record represents as not the radiosignal, but the voltage of manipulation, received after FSK, FМ or АМ detector.

Just for such cases the double-half wave detector, which solves this problem successfully had been added. In generall it concerns FSK-2, modulations C4FM and some other signals.

More important updating, is the introduction of module of FSK-2 demodulator.

Current realization is the base concept, and means further development.

Synchronization on clock frequency is carried out manually (at least currently). It isn't difficult, but demands some skills.

Exact phasing is should be done in last moment/time!

The first step: to expose/specify exact clock frequency. It should be done by zero beating, which are well visible at the corresponding scale on an axis X. Frequency is entered directly in manual from the keyboard (at it finished of input must be pressing of "Enter" key), or changes through control elements on the panel.

The second step: is the installation of rough phasing through the slider in the bottom of display window.

Last step, is adjustment of a phase for reception of as much as possible accurate clear picture.

After all these actions, a line of action/line of solution should be exposed in the necessary position (usually on the middle), if the signal is qualitative enough, and it was possible to receive a good picture of separation of levels. And it becomes possible to get the bit stream. All what is above the line of solution is considered to 1(0), all that is below the line of solution to 0(1).

I want to underline, although the module is intended for FSK-2 signals, it has much more extensive application field, as all SA tools.

In particular, with its help it is possible to realize the following tasks easily:

1 - to identify such kind of modulation as C4FM

2 - To realize a quality estimation of various signals etc.

The more detailed information about how to work with this module and practical application of new SA features is described in the article An output from discriminator and program processing.

Good Luck~

OFDM, COFDM: CIS-59, Known as the "Ferrite", perhaps an experimental(inner) brand.

2010-09-03T14:11:00.000-07:00

CIS-59, Known as "Ferrite", perhaps an experimental(inner) brand.

Ch-59, Br-40 Hz, Sh-50 Hz, QAM-64, k = 1/4 = 0.25

An exellent record of this signal, sent by YuriVr.

Author: SergUA6

Band Width ~3000 Hz

Low Range ~330 Hz

Baud Rate 40 Hz

n-Ary (PSK/MPSK) QAM-64

Count of Carriers 59

Step between carriers 50 Hz

ACF ~175 ms

RX mode SSB

Sonograms

pic.1 Generall view

Diagrams

pic.2 Phase constellation in the channel

pic.3 Synchronization symbols (every 7th symbol)

Pictures

pic.4 ACF

CIS-59 "Ferrite" - The name "Ferrite" quite possibly is not wide known. We can suppose it is an internal trade mark of the manufacturer. The manufacturer is unknown (at least to me), but it is known that it is domestic (Russian) development . The record has an exellent quality, all parameters are easily defined in SA.

I would like to mark some features of this signal, these are:

special symbols the synchronization/adaptations (every seventh symbol).
the form of constellation QAM-64 is characteristic more likely for NATO signals, than for signals CIS.

The maximum technical speed = 59 (quantity channels) *40 (clock frequency of manipulation) *6 (quantity of bits in one position QAM-64) minus synchronization symbols, that makes 14160 - (14160/7) ~ approximately 12137 bps.

The signal is generated by A model.

The detailed information about models/types of OFDM is in article/update version SA update to version 6.1.2.7 & OCG update to version 1.0.2.7

English version SA update to version 6.1.2.7 & OCG update to version 1.0.2.7

Spanish version Actualización de SA a la versión 6.1.2.7 y de OCG a la 1.0.2.7

Parameters of OFDM signals. and SA update version 6.2.0.9

2010-09-02T07:56:00.000-07:00

Update SA to version v 6.2.0.9

Function of obtaining an exact value of the clock frequency manipulation signals OFDM is added in OFDM module.

Of course it is only within reasonable limits, we are not talking about the absolute accuracy, since all measurements are statistical in nature, and there is always some error. Just this error, in our case, is very small.

Also we updated OCG program to version 1.2.0.9

Small calculator for getting basic parameters of OFDM with CP is added.

We also created an interesting article Parameters of OFDM signals.

This article contains:

an interesting information about parameters of OFDM signals
implementation of SA new version at analysis of OFDM signals
examples on the real signals from the air
features of OFDM analysis (like "magic" coefficient "k")
and small lessons how to analyze OFDM signals

We are very hope you will find it interesting and usefull.

Super DARN- is the interesting signal from UDXF discussion.

2010-08-13T13:52:00.000-07:00

After some discussions, it became known, that the mysterious signal, about which we were spoken about in previous post is Super DARN (Finland).

Here is some details about this signal:

Super DARN

Super Dual Auroral Radar Network

An awesome example of Super DARN signal, send by RadioKoteg.

Author: SergUA6

Band Width ~5900-6000 Hz

Low Range hopping

RX mode source IF record

Sonograms:

pic.1 Generall view

pic.2 Detalization
pic.3 Detalization

Super DARN - there is developed enough international network for studying of an upper atmosphere and an ionosphere (Super Dual Auroral Radar Network) regions. The signal of one of radar of this network is represented in this case. The signal is curious enough, as possesses rather narrow spectrum of radiation, that is not characteristic for various probing systems. As a rule, spectrum's width of such systems, is located 20-80 kHz and higher limits. In generall, the measured parametres have relative/conditional character as can vary depending on tasks.

Many thanks to Leif Dehio for help with identification of the signal.