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DVBfanatik

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Reply with quote  #16 
OK if we are in DVB-S2 8PSK mode I agree that we need 3 bits by Symbol, so 90Mbps will give maximum of 30 MS/s. It's not a surprise in this case.
But I was thinking about DVB S2 QPSK mode, that is a mode that is allowed ( I don't know if it is really used on broadcast satellite) in standard description. Why max Symbol rate will be so lower than DVB-S QPSK ?
That's why I was surprise...
Perhaps in datasheet, they will give a value that will be sure in all conditions, so give the lowest corresponding to 8PSK
 
But, as I said, it's not a strong problem for Ham Radio transmission, we have only one Channel / carrier and max SR I have ever used was 6000kS/s when I transmit in full HD.
But for Feed Hunters it can be a restriction.


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Derrick

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Reply with quote  #17 

Quote:
Why max Symbol rate will be so lower than DVB-S QPSK ?

DVB-S2 digital demodulation is more complicated and therefore needs more processing power. I guess to reduce the dissipation power, the clock rate will be lower for dvb-s2. At the output of the (ZIF)-tuner you have the analogue IQ-signals which will be converted to digital in the input stage of the demodulator. As you know, the A/D converter needs to run at twice the highest symbol rate (Shannon). At this stage there is no difference between S and S2. But the rest is much more complicated. Apparently modern chip structures can handle S  and S2 at the same speed. Alas it's almost impossible to get detailed descriptions of these chips without NDA.

wejones

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Reply with quote  #18 
Quote:
Originally Posted by DVBfanatik
Yes you are surely correct. I currently only use DVB-S and I know I can go up to 45 MSymbols/s, but for DVB-S2 the datasheet show a limit of 30 MSymbols/s . .....


A slight qualification of the above.... 
My TT3200 will do greater than 30 MS/s in DVB-S2, as long as the signal is QPSK.   For example, I now have the 4020 DVB-S2 QPSK transponder on Galaxy-17 locked, giving same S/N as the TBS6925.  It does seem to not work on DVB-S2 8PSK above 30,  on the same sat, however. 


Derrick

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Reply with quote  #19 

@DVBfanatik during the development of your tool you must have come across the question whether the IQ signals are normal or swapped (spectral inversion). IMHO in CrazyScan the display is inverted.

I've checked this again with a debug driver for the TBS8921 written by @cody from TBS. Here an example (9E, 11747H)





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crazycat

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Reply with quote  #20 
Quote:
Originally Posted by DVBfanatik
OK if we are in DVB-S2 8PSK mode I agree that we need 3 bits by Symbol, so 90Mbps will give maximum of 30 MS/s. It's not a surprise in this case.
But I was thinking about DVB S2 QPSK mode, that is a mode that is allowed ( I don't know if it is really used on broadcast satellite) in standard description. Why max Symbol rate will be so lower than DVB-S QPSK ?
That's why I was surprise...
Perhaps in datasheet, they will give a value that will be sure in all conditions, so give the lowest corresponding to 8PSK
 


QPSK som times used in DVB-S2 mode with modcode 8/9, 9/10. So advantage only in more advanced LDPC/BCH FEC.
4example 2 QPSK transponders with maximal FEC for DVBS and S2:
----------------------------------------
Frequency: 11798.797 Mhz
Symbol rate: 27498 KS
Polarization: Horizontal
Spectrum: Inverted
Standard/Modulation: DVB-S/QPSK
FEC: 7/8
RollOff: 0.35
RF-Level: -30 dBm
Signal/Noise: 15.2 dB
Carrier width: 37.123 Mhz
BitRate: 44.348 Mbit/s
----------------------------------------
----------------------------------------
Frequency: 12012.949 Mhz
Symbol rate: 27498 KS
Polarization: Vertical
Spectrum: Inverted
Standard/Modulation: DVB-S2/QPSK
FEC: 9/10
RollOff: 0.35
Pilot: off
Coding mode: CCM
Long frame
Transport stream
Single input stream
RF-Level: -30 dBm
Signal/Noise: 14.7 dB
Carrier width: 37.122 Mhz
BitRate: 49.194 Mbit/s
----------------------------------------

So - plus 5Mbit/s

P.S. Maybe STB0899 support SR up to 45000Ks for DVB-S2/QPSK, but not used anywhere. But for DVB-S2 8PSK real maximum is 30000Ks (tested on 21.6E, 11449,V,30000,8PSK,8/9 = ~80Mbit/s).

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Strong offset dish 0.95m on Powertech DG240 motor + ALPS BSTE8-751B Ku-Universal LNB. Variant CA-902 0.95 offset dish with 3xDreamSat DS-8 Ku-Universal LNBs (13E+4.8E+4W) + Variant CA-600 Ku-Circular LNB 36E + DiseqC 1.0. STB: GI8120 Lite. PC DVB: Omicom S2 PCI; TBS 6983 PCI; TBS QBox-CI USB(5980), 5927.
crazycat

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Reply with quote  #21 
Quote:
Originally Posted by Derrick

IMHO in CrazyScan the display is inverted.


DVBfanatik can check this with modulator connected directly to TT S2-3200 in CrazyScan.

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Strong offset dish 0.95m on Powertech DG240 motor + ALPS BSTE8-751B Ku-Universal LNB. Variant CA-902 0.95 offset dish with 3xDreamSat DS-8 Ku-Universal LNBs (13E+4.8E+4W) + Variant CA-600 Ku-Circular LNB 36E + DiseqC 1.0. STB: GI8120 Lite. PC DVB: Omicom S2 PCI; TBS 6983 PCI; TBS QBox-CI USB(5980), 5927.
wejones

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Reply with quote  #22 
Quote:
Originally Posted by crazycat
...
P.S. Maybe STB0899 support SR up to 45000Ks for DVB-S2/QPSK, but not used anywhere. But for DVB-S2 8PSK real maximum is 30000Ks ...


I'm confused re why you say it is not used anywhere, when I gave an example above? 


DVBfanatik

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Reply with quote  #23 

Sorry I m not at home for the moment and during traveling i don't get wifi free when I want..
For max SR in DVB-S2 I will test as soon as possible with my Dektec DTA107A-S2 that can modulate in both modes.
.
For STB0899 structure and demodulation in DVB_S2 mode, I have all informations on this chip to program it, so as I have  spent many hours  learning how to set its parameters in DVB-S QPSK mode
 

  my first idea is that yes it can go up to 45MS/s in DVB-S2 QPSK mode and up to 30 MS/s in DVB-S2 8PSK mode.

Techno Trend write about TT S2-3200 in DVB-S mode: “SCPC/MCPC support 2 Msymbols/s to 45 Msymbols/s”

Minimum announced is 2MS/s but I can say that all TTS2 3200 I have tested (about 20 units) could all run very well at 1MS/s –( it’s the first quality we must test in Ham Radio practice)

Some producer can announce mini 2MS/s and you can reach 1MS/s without problem, some others announce 300 kS/s and you have difficulties under 800 kS/s…. So the best is also to test.

I have just  read again what ST MicroElectronics write about STB0899:

“The demodulator supports QPSK in DIRECTV and DVB-S legacy transmission (up to 45 Mbauds), plus 8PSK in DVB-S2 transmissions (up to 30 Mbauds).”


As far as I can remember in DVB S2 mode, only the demodulation structure is different (LDPC and BCH decoder instead of Viterbi/reed solomon decoders…) but STB0899 clocks remain same.

We can play with mutltiplicators and divisors from quartz base frequency to  set as we want and we can also go out standard values given by producer like overclocking PC CPU…

PLL can be programmed to use reference from 4 to 30 Mhz, 27Mhz recommended but we can test extra values. For best receiving with slow SR, I play with STB0899 PLL multiplicators to have slower sampling rate and  longer loops so less loops and more stability as it is the principal problem for slow SR. When we lower SR, SN/MER will  be lowered too, depending of da costas lock loop stability, so dificulties appear…

Standard BDA drivers not always play with all these parameters…

If you look at Tutioune interface you will see all PLL parameters that can be changed

@ Derrick : For IQ inversion Tutioune show it. (yes I have work on these value and and more information about IQ- DC offset and IQ imbalance values. And Tutioune display also an oscilloscope screen with IQ signal

If you cannot test with Tutioune, when I will go back to home tomorrow, I will test what say Crazyscan and what say Tutioune about that.

You can check on these picture all PLL parameters setup Tutioune offer and Information about IQ inversion, offset and imbalance


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DVBfanatik

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Reply with quote  #24 
Tutoune screen with all parameters to set ( disappear when I edit my last post)

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crazycat

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Reply with quote  #25 
@wejones: but you not give info about transponder (freq, SR) and i don't understand your post sorry

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Strong offset dish 0.95m on Powertech DG240 motor + ALPS BSTE8-751B Ku-Universal LNB. Variant CA-902 0.95 offset dish with 3xDreamSat DS-8 Ku-Universal LNBs (13E+4.8E+4W) + Variant CA-600 Ku-Circular LNB 36E + DiseqC 1.0. STB: GI8120 Lite. PC DVB: Omicom S2 PCI; TBS 6983 PCI; TBS QBox-CI USB(5980), 5927.
wejones

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Reply with quote  #26 
Quote:
Originally Posted by crazycat
@wejones: but you not give info about transponder (freq, SR) and i don't understand your post sorry

Sorry, I left out the SR.  It was 31250.  Also polarity, ie V 
Gave the rest in msg 18 above,,    ie Galaxy-17  4020 DVB-S2 QPSK .  There are a few of these 31250 DVB-S2 QPSK transponders which carry video (usually encrypted, but not always) on G-17, and on other sats.  These have been discussed in this forum.   So DVB-S2 QPSK with SRs greater than 30000 IS being used.


A 2nd example, on the same G17 sat, was the 3800 MHz transponder. I did a screen capture on this yesterday with Crazyscan, see attached.  Also a screen capture of my TT3200 locking the same transponder. 


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DVBfanatik

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Reply with quote  #27 
@Derrick (#17)
I have check Inversion:
Crazyscan says same thing as Tutioune
Astra 19.2 E,   11508 Mhz V
TT S2-1600  Crazyscan :==> "spectrum Inverted"
TT S2-3200  Tutioune: ==>"IQ swap = ON"
 but many things can change IQ inversion
if you local oscillator (LNB or converter) works in add mode original signal inversion remain same
if your local oscillator give a subtract like (Freq = local frequency - direct frequency) your IQ signal inversion mode will be inverted....

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Derrick

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Reply with quote  #28 
thx @DVBfanatik. I see, it's not that easy But we have to exclude all possibilities that can can cause mupltiple swaps. What about @crazycat's proposal to connect directly to your modulator?
DVBfanatik

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Reply with quote  #29 
I have not to do it again, since one or 2 years I spend hours and hours to send DVB modulation to my TT S2-3200 to develop Tutioune and setup measurements as perfect as possible. with DTA107 I can change level of transmission and also I can change digital S/N by adding dephasage or jitter in modulation, so it's fantastic as help for measures made by Tutioune .
When I modulate directly from one of my DVB-S modulators ( I have 3 different modulators : 1 Dektec DTA107S2, 1 Newtech DVB2080 and 1 Minimod),  I always find "IQ swapped" with a TT S2-3200 directly connected to it.
That do not means that spectrum is inverted, that only means that STB0899 I Q inputs must be swapped to be demodulated. That means that the STB0899 works in inverted mode because of the manner Technotrend design electronic circuit from STB6100 IQ output to STB0899 IQ input.
So Tutioune just say what STB0899 say ' IQ input  must be swapped '. But if we don't speak of "swap mode" in STB0899 but something like "Spectrum inversion", if we want to speak about signal received and not STB0899 status, I think we must say "spectrum not inverted" - (at antenna input) or specify "spectrum inverted" at STB0899 input.
As Crazyscan say same thing as Tutioune, Crazyscan 'spectrum inversion" is at STB0899 input and not antenna input.And for a TTS2-3200 "spectrum inverted" in STB0899 signify "spectrum not inverted" in antenna.


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TUTIOUNE Developper. more than 40 DVB PCI/USB cards at home - 4 PC working DVB _ Ham Radio DVB transmission - DATV -
Derrick

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Reply with quote  #30 
Quote:
As Crazyscan say same thing as Tutioune, Crazyscan 'spectrum inversion" is at STB0899 input and not antenna input.

in clear: what we see is swapped by the receiving equipment. A normalized reading  of the demodulated signal should be "normal"

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