Explanations Tutioune Version 0.7

Messagede oh6mqm » Dim 3 Juil 2011 14:45


Thanks from excellent software.

Usage is easy.

Is there somewhere available detailed information from all fields of software.
Some fields are not clear for me
Messages: 19
Inscription: 19 Juin 2011

Re: Explanations

Messagede F6DZP » Lun 4 Juil 2011 13:22

Thank you for your encouragements.
Here some explanations:
I separate the Tutioune interface in 12 zones :
Tutioune 0.7 alpha english numero copie.jpg
Tutioune 0.7 alpha english numero copie.jpg (402.21 Kio) Vu 12992 fois

Command zone:

en_commands.jpg (60.05 Kio) Vu 12992 fois

You will see on these buttons the values you have written in the Tutioune.ini file.
This allow you to setup you preferred presets.
To lock on a DVB-S station begin to click firstly SYMBOLRATE and after click FREQUENCY.
Normally you have just do do that to get a DVB station.
GO! is just for repeating all setup to STB0899.
Reinit is to be use when you have change too much parameters ans are lost, or when any problem appear.
It will rewrite all standards parameters in the STB0899 registers but SymbolRate and Frequency.
Reset is for my own debuging purpose for moment...

You can also set a voltage if necessary for your preamplifier (or LNB)
You can also set the FEC
Remember that STB0899 always works in auto detect FEC mode, but with these 6 little checkboxes you call tell him which FEC searching.
You can set on all 6 checkboxes, STB0899 will find the good FEC value between all of them, but if you set on only one or two checkboxes, STB0899 will find more quickly.

Tuner setup zone:
en_tuner.jpg (45.44 Kio) Vu 12992 fois

The Tuner reference name will be automatically detected (STB6100 or STB8260)
for the STB6100 you can setup Gain and Bandwidth.
Before detected a signal don't set the Gain in Auto mode.
The auto Gain mode can be set after a frequency locked to obtain a better MER which is the best when AGC1 is about 100U.
the aim of AUto gain is to search the "near 100U" position.

Frequency zone:
en_Frequency.jpg (92.61 Kio) Vu 12992 fois

Here you can write frequency you wish to receive. Just type the digit in the rectangle.
If value is in a RED rectangle, the Tuner has not been well programmed, try again.
Most of time the rectangle is green, the frequency is well programmed.
You will see just under the real frequency programmed in the tuner STB6100( frequency set). This frequency depends of quartz oscillator and step possibilities.
But the Transmitter frequency is often not the same you asked, so there is a digital corrector system called DEROTATOR that will search the deviation with the frequency found. For the moment the Derotator can find a frequency +/- 450 khz around the programmed frequency.

With some DVB cards I succeed to catch a frequency up to + or – several megahertz around the programmed frequency.
I suppose that, when I will know more STB0899 secrets, I will be able do enhance this possibility.

So, the Derotator can find the deviation or Offset with the true frequency to decode.
The Offset detection system will do that. It is set ON when you write a new frequency to get, and go automatically to OFF when it has found the deviation.
There are also 3 algorithms possible for the Derotator phase detection. For QPSK the best is to use firstly algorithm #1 and only after lock we can use algorithm #2 if the MER is low ( below 6dB) to help in phase stability.

Frequency and Symbol Rate synchronization are made by a double PLL (Costas Loop) .
We can see the PLL parameters (alpha, beta, Natural frequency and Damping Factor). For specialist. Take care changing alpha,beta parameters. Normally you don’t need to change the PLL parameters. I have put them just to study them and test the best values.

The PLL must be well locked for good demodulation possibilities. The Vu-meter show how you are locked. The needle must be in the green zone.
The Threshold is not very important, it is just the value the vu-meter need to reach for the Carrier LED to go green.

The Cycle button is for starting a timer that reset the Derotator every 2 seconds when there is no signal demodulated (led TS STATUS red). It's very useful when you want to let you Tutioune scanning a frequency during hours and specifically if you use the web monitoring option. A friend can see on the Web that your Tutioune is waiting on a frequency for a signal to come and can try to send something or test his equipment, even if you are sleeping or not there...
I use this system sometimes just to be given notice that a friend is transmitting.

SymbolRate zone:
en_SymbolRate.jpg (83.71 Kio) Vu 12992 fois

Normally you have just to use Zone 3 :
Write Symbol Rate in KSymbols. There is a little error percentage allowed, it written just under the SR set, you see offset max allowed.
Under, you can see the offset found, and so, the Symbol Rate worked after offset correction.

This is the second PLL loop linked with the frequency PLL loop, so the locking of the system depends of the 2 values. You cannot be very well locked in frequency if your have not put a good Symbol rate that can be locked too.

The Vu-meter show how you are locked. The needle must be in the green zone.

As for the frequency PLL, you can change the alpha and beta parameters of the PLL and look at alpha and beta timing, natural Frequency and Damping Factor.

Zone. 3bis

You need to use this only if you don’t know the Symbol Rate of the station you want to receive. Just to change the search mode ( stop by default) to Auto.
You play with it if you want , a friend send you a DVB-S transmission and you don’t know the symbol rate… fun to play…

AGC tuner
en_AGC1.jpg (53.08 Kio) Vu 12992 fois

AGC tuner send directly AGC voltage (0-2V if +3dB on) to the tuner STB6100 gain stage. Nothing difficult to understand I think for Ham Radio.
You can change the compensation speed and the reference.

I write the action in dB and also the value in Units (94U for this example)
The STB0899 give best MER when AGC1 is about 100 units.
( the Auto gain option- for the tuner- search by himself the best value)
The range of action for this AGC is about 70 dB.

AGC post Nyquist filter

en_AGC2.jpg (52.18 Kio) Vu 12992 fois

The AGC2 act on IQ digital signal inside the demodulator, just after the Nyquist Filter
If you change the reference you will see directly the constellations being +/- concentrated and going towards or far from zero. This change the MER reading, but MER calibration is accurate only for default values. If you change them, MER values are no more accurate.
I use this AGC2 value to compute RF signal value for lowest values , when AGC1 don’t move or is below 40U.

IQ setup
en_compensation IQ.jpg
en_compensation IQ.jpg (46.16 Kio) Vu 12992 fois

IQ swap :
Depending of transmitter, tuner receiver, frequency converter you can use, IQ signals are sometime swapped. So we always start in auto mode and the STB0899 will detect automatically the good position. If the green led is on it is because it has switched to swap mode.
IQ compensation :
IQ signals are not always well balanced and zero DC tuned, so there is the possibility to compensate DC offset et Imbalance between I and Q
It’s very useful for Ham Radio that are developing their home-brewed modulator for observing IQ imperfections


en_equalizer.jpg (51.24 Kio) Vu 12992 fois

The equalizer is a system for attenuation of echoes in coaxial cable.
You can change speed.
There are also 3 reset options, depending of what can arrive to your signal.

en_measure.jpg (94.71 Kio) Vu 12992 fois

RF Power

This is a RF power information , not a RF level.
For the same output power, if you change the SymbolRate of your DVB modulator you will see on a spectrum analyzer a change in the max level value.
When we change the SymbolRate value, at reception the level value change, power value don’t change.

IQ level
Just to see the digital IQ level inside the demodulator. Not very useful but funny to see.
I can show the eye diagram because the I2C connection I use to access IQ values doesn’t allow speed enough.

S/N MER and constellations

The most important value
MER 33dB.jpg
MER 33dB.jpg (43.16 Kio) Vu 12982 fois

MER 18dB.jpg
MER 18dB.jpg (46.42 Kio) Vu 12982 fois

MER 6dB.jpg
MER 6dB.jpg (66 Kio) Vu 12982 fois

On this Tektronix documentation :http://www.itl.waw.pl/oferta_pliki/wypozyczanie/pdf/g2/Tektronix-DMA120.pdf
we can read:
"Modulation Error Ratio(MER):
ETSI ETR290 indicates that MER is the best overall “figure of merit” measurement to determine QAM signal quality. Although bit error rate (BER) has been widely addressed as an important digital transmission “figure of merit” measurement, MER provides a much earlier indication of transmission impairments."

We receive SR number of Symbol by second . In DVB-S QPSK modulation, each Symbol can be considered as a couple(I,Q) corresponding to a point in the diagram constellation.
Each of the four positions in the four quadrants of the constellations-diagram can be decoded as 00, 01, 10 or 11
So to be well decoded , each point need to be near the target of quadrant, a place where it is easy to find to which quadrant the point belong.
More reception is difficult, more points dispersion is great.
MER calculate this dispersion.
MER schema1en.jpg
MER schema1en.jpg (43.68 Kio) Vu 12981 fois

MER 18dB explications en copie.jpg
MER 18dB explications en copie.jpg (75.07 Kio) Vu 12977 fois

MER(dB) = 10log(Average symbol power ÷ Average error power)

MER is calculated by doing average of a number of IQ couples = Symbol.
Number of Symbols on which MER is calculated can be set in Tutioune to 4kS, 16kS,64 kS or 256 kS (Noise Time)
MER is given in dB so is easy to use and understand.
It’s a method of measuring digital S/N

Here you can see the reception possibilities with a quasi constant RF level/power:

instruments MER 18dB level -41dBm.jpg
instruments MER 18dB level -41dBm.jpg (92.8 Kio) Vu 12981 fois

instruments MER 6dB level -39dBm.jpg
instruments MER 6dB level -39dBm.jpg (107.27 Kio) Vu 12981 fois

instruments MER 4dB level -39dBm.jpg
instruments MER 4dB level -39dBm.jpg (113.86 Kio) Vu 12981 fois

instruments MER 3.1dB.jpg
instruments MER 3.1dB.jpg (103.7 Kio) Vu 12980 fois

Looking at these 4 panels, we can see that when MER goes down, constellations clouds disperse Viterbi corrector begin to work and progress, you can see numbers of bits corrected by Viterbi growing and when Viterbi corrector can’t correct all Symbols it receives, Reed Solomon corrector wake up to add another correction and we can see the number of bits or bytes corrected by Ree Solomon.
en options and VBER.jpg
en options and VBER.jpg (98.1 Kio) Vu 12966 fois

In this example, we have Vber in % to 9%, Bit corrected by Viterbi = 26800 and bits corrected by Reed Solomon 18. TS status is green so all DVB packets are OK for decoding.

Above these measures we can see :
- IQ Constellations option that allow to choose where are taken IQ Symbols to display.
- Noise Time option that allow to change number of Symbols used to calculate MER

Tutioune give numbers of bits corrected between to reading of STB0899 registers, the timing is between 2 Screen update. Just to look at these numbers that grows like VBER and CBER on a professional analyzer Sefram 7856:
BER et MER.jpg
BER et MER.jpg (89.53 Kio) Vu 12966 fois

A QPSK (DVB-S) packet is made of 204 bytes ; a packet is 'wrong' if it has more than 8 wrong bytes
(correction with Reed Solomon coding).

BER= Bits error rate
The BER is defined as the ratio between erroneous bits and the total number of transmitted bits
CBER = BER before Viterbi (inner) decoder
This measurement gives an in-service indication of the un-coded performance of the transmitter, channel and receiver.

VBER = BER before RS (outer) decoder
The BER is the primary parameter which describes the quality of the digital transmission link.

UNC = BER after RS (outer) decoder
To measure whether the MPEG-2 TS is quasi error free

MER = modulation error rate

When the numbers of bits corrected are too high, it signify that Viterbi and Reed Solomon cannot correct all the stream, Vber% is high and TS STATUS go RED.
When TS Status is Red, we have a transport stream that have errors. If you put an analyzer at this output ( like Tsreader) it will see errors and if we decode video and audio we will have some freeze or artifacts.
When TS Status is Green , we have a transport stream without error, so we can analyze and decode the DVB Tables to obtain PIDs and get video and audio without problem (if we have the good Codecs installed)

When TS status is green you will see button "ShowVideo" and button "Analyze" beginning Enabled .
So you can now click on "Showvideo" to call a second software called "showvideo.exe" - if corrected installed -
and you can click on "Analyze" for decoding some informations about the DVB table coded inside your stream.

Transport Stream Analyze

en_analyze with PID.jpg
en_analyze with PID.jpg (54.86 Kio) Vu 12962 fois

When TS Status is green you can click on Analyze button
Tutioune will try to extract DVB tables informations. As you have clicked at any time, sometime there are many errors because tutioune start analyze at a bad place and begin to find incomprehensible informations = errors. Just click the Reset button to start again an Analyze with error counter to 0.
After Reset you see 0 errors and numbers of PMT, PID,PES founded.

Most important PID are shown at lower part : PMT PID, video PID and audio PID.

Web info
en_Web_Info.jpg (39.41 Kio) Vu 12992 fois

Here you can see all informations that will be sent to the Tioune Monitoring system. /page.php?p=monitor1

If you have well rewrite your own coordinates ( Ham call, QRA locator, town, …) in tutioune.ini file, you will see them and not mines.
Take care to have these good informations before clicking the WEB button !
By clicking on the Web button at right-bottom of Tutioune window, your Tioune Monitor will be automatically created on the Tutioune monitoring Web page on this Forum, if it doesn't already exist.
You and your friends will be able to see in real time your measures on this Web page. Your Icon on Google map tutioune.php?what=map will go green. And if you are receiving a good DVB signal, your green Icon will start to jump.

If you want to leave Tutioune looking a special frequency, waiting an eventual transmission you have a button « Cycle » in the Derotator zone that will reset Derotator search every 2 seconds.

Have fun with Tutioune!

You can add some questions if something is not clear.

Jean Pierre F6DZP
Dernière édition par F6DZP le Mer 2 Nov 2011 09:03, édité 30 fois.
Messages: 668
Inscription: 24 Déc 2010

Re: Explanations

Messagede F6DZP » Mer 6 Juil 2011 06:44


I have finished my first explanations.

Now I wait for your others questions if you have some. ( not too much I hope)

Jean Pierre F6DZP
Messages: 668
Inscription: 24 Déc 2010

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