I did a test with the beacon I get both 5000000- 6000000 no problem today it is raining and I sell the signal
73 ik1hgi Tony
Software DVB-S demodulator
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Hi,
Rolloff for beacon must be 0.25 or 0.35 ?
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Hi,
SWL - markro92 sometimes I get signal and sometimes I can not get signal or is poor.
May be is a CPU - but I can not see 100% CPU.
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Ciao,
Il rolloff per il faro deve essere 0,25 o 0,35?
The rolloff for the beacon must be 0.25 or 0.35 ok you use it to understand what the best reception yield and image quality ... mine are the only tests for the quality of the video
73 IK1HGI Tony
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Hi,
I started to test how to decode DATV with this software, and I was able to decode a 333ks/s flow with my RTL2838 and with some help from Luc, ON7KEC.
Sounds very interesting and really a good job.
Unfortunately, I got some trouble as beginner to got a proper constellation and to quickly increase the confidence synchro.
I used some snapshot found on this forum, but it still difficult to find a smoke tutorial / howto from coarse tuning till fine tuning
The baseband processing sounds pretty clear to me and I understand that the software will drive the LNA, I / Q parameters and correction.
Therefore, at least few questions...
- I used for a 333ks/s a Kp of 1/16 and Ki of 1/16384 as timing recovery info : I guess that depending on the symbol rate and eventually modulation type, we could consider associated suitable values (and which one)?
In other case, based on the sample rate, how can we "tune" this parameters (debug stats / plots) ?
- For the carrier recovery, I usually starts with high values of Kp (i.e 15.57) and high value of Ki (i.e. 0.250); when the software starts to synchronize, I'm reducing these parameters in order to optimize the IQ plot.
Is it the way to proceed (it's a bit tricky there
) ?- Regarding equalizer section, with lower Taps and Gainu values sounds to give good results.
Could someone clarify these questions or provide me relevant links ?
73, F8ACB Samuel
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SWL - markro92 Are there any plans to intoduce somewhere in the GUI a simple MER display ? (Modulation Error Rate in dB)
I think that whould be very useful for people that are tweaking their hardware, RX, antennas, LNB etc. to "measure" some kind of relative improvements or changes. Similar to the hams always giving MER reports when using Minitouner hardware...
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F8ACB: sounds fine to me
Timing recovery isn't that picky, but for carrier recovery, the approach you have is correct. I'm using gain values slightly below 1 for carrier recovery gain once i acquired lock. damping all the way to the lowest setting. damping pretty much controls how fast the NCO adapts to momentarily changes in carrier frequency. If you have large frequency drifts, it couldn't keep up with a low damping value. But that's unlikely to happen anyways.DJ0MY: i played around with that, but i never got it working properly, so i kinda gave up. if someone knows how to calculate SNR correctly can you provide me with some infos? I think it can be done with symbols only. I also only need it for PI/2 BPSK, because i can use the PLHEADER symbols for it i guess.
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SWL - markro92 : Maybe the author of the Minitioune Software, Jean-Pierre F6DZP could help?
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@SWL - markro92 Thanks for your feedback, hopefully there will be some activity during the week-end to improve the skills....
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you can use the LDCP-Worker values to determine if your RX gets better.
If you tune to the Beacon you can see the values decrease with better reception.
Of course this values change also with the usage on the WBTP and the BW and your CPU Speed.
I optimised my RX system with help of that values (only beacon on the WBTP active!)
See attached picture.
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@DB8TF: that's true. You could also use the console output, which tells you how many iteration the LDPC workers need. This is independent from the CPU speed. But of course this is a very limited way of measuring performance
I'm currently updating some stuff. Just added 16-bit processing path, so that SDRs with more than 8 bits resolution are fully supported, instead of only truncating to 8-bit. I've also added Baseband AGC, instead of only using the Equalizer. The advantage of doing that, is that Timing and Carrier recovery gain values are no longer affected by input gain. I'm also planning to remove the matched filtering GUI elements, because that's the least important setting, and it can be automated easily. That's because the number of RRC Taps needed can be estimated by samplerate versus symbolrate, and the rolloff factor is coded inside the DVB-S2 header. I'll now try to fix the decision directed equalizer algorithm, and implement the missing modcodes, which are 16APSK and 32APSK. After that, i'll improve the demodulator code, and then you'll also get a linux version. Got plenty of time for coding next week.
73's,
Marcel
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Thank you Marcel. That sounds like great improvements in the pipeline. Do you think that by ading the 16 bit processing path you may have slightly less quantisation noise which could potentially lead to a slightly improved RX performance with SDRs >8bit....???
Or am I misinterpreting something?
73, Oscar
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QO-100 WB Beacon Nuovo parametro: DATV beacon:
Centro 10.4915 1500 kS DVB-S2 QPSK 4/5 FEC 0,25 rolloff, C / N = 4,6dB 2.383 MBit
75 ik1hgi Tony
External Content www.youtube.comContent embedded from external sources will not be displayed without your consent.Through the activation of external content, you agree that personal data may be transferred to third party platforms. We have provided more information on this in our privacy policy.NOW SWL - markro92 YOU HAVE TO CHANGE THE SYM_RATE PARAMETERS ADD 1500 SR
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@IK1HGI:
Just modify the config.ini
73s
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Hi, after the changes in beacon I can receive the beacon very easy with Pluto or RTL even with a dual core.
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@ IK1HGI:
Basta modificare config.ini
73s
I hadn't thought about it, thanks for your confirmation
73 Tony ik1hgi
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SWL - markro92: When I try to receive the beacon (with version .16 and Pluto) I manage to get a stable and nice constellation, but as soon as LDPC worker is activitaed the constellation frequently loses lock and nothing is streamed therefore to VLC.
Could this be a CPU issue? (its a i5 3rd generation)
