Crash on Fedora with SDRplay

[fjl82]

I've just built this project from source using qmake and make on Fedora 34, and it starts up and detects my SDRplay RSP1a fine. But when I hit 'start', the only things that happen is the gain counting down, then the UI freezing up and a few seconds later a crash with message "Illegal instruction (core dumped)". No other output in the terminal whatsoever. Disabling AGC does not help.

Any way to fix this? Do you need more info?

[Oleg-Malyutin]

I do not speak English. I use translator.
Initially, the project was not designed for receiving from an antenna.
Good signal strength and a matched antenna are required.
In practice, the gain reduction is at least 45 (gain:> 45).
It is necessary to improve the algorithm for determining the P1 symbol. This is where a weak signal crashes and a sharp consumption of CPU resources.

[fjl82]

I tried a few different gain values, but this doesn't seem to work at all. At least with autogain, I get a few seconds of constellation diagrams. When I enter gain manually, everything stays empty, and it doesn't seem to make an attempt at receiving.

I don't think it's a problem with bad signal. The signal looks fine to me in GQRX:

That's a pity, I was hoping this was going to work. This is the only project so far that seems capable of receiving DVB-T2 from an SDR. The RTL sticks only support DVB-T, which has been replaced in most of Europe years ago by T2, and the Linux DVB kernel stack relies on the hardware doing all the decoding (which an SDR is not going to do). I hope someday you can get this working properly.

[Oleg-Malyutin]

I meant 45dB with automatic gain. This is an indication of the signal strength at the antenna.
With a worse signal, the P1 symbol may be incorrectly assigned, and also there may not be enough performance for the LDPC decoder.
There have already been consultations with a similar problem and this was solved by a good antenna.
This is a test project and does not include CPU overload protection.

[Oleg-Malyutin]

P.S. SDRPlay no gain in db, it is gain reduction db

[rapbando]

@Oleg-Malyutin Hopw difficult would be to add compatibility for Hack-RF SDR?

Cheers

[Oleg-Malyutin]

I don't have HackRF.
I think it's not difficult. I tried SdrPlay on 8 bit and it worked.
The condition is an unprocessed signal with HackRF , i.e. without DC offset and IQ imbalance remove.

Regards.

[rapbando]

Is possible for you to integrate with Soapy so HackRF and other SDRs can be used?

[Oleg-Malyutin]

Unknown.
As I wrote earlier, an unprocessed signal is needed (the driver's own DC offset and IQ imbalance remove functions are not suitable for DVB-T2).
Soapy may not contain any driver settings to disable internal enhancements.

[rapbando]

@Oleg-Malyutin

I added the QT modifications nedded for HackRF SDR. Now before compiling I need to create rx_hackrf.hheader and rx_hackrf.cpp source code, could you help me since you already know all the requirements? I would very gladly send you a support donation if you can.
Here and here I link for your reference the osmosdr analogues files for intefacing with hackrf.

Cheers

[Oleg-Malyutin]

I'll see. I don't promise a quick answer.
This will be without a sanity check.

[rapbando]

@Oleg-Malyutin

Great, no rush whatsoever!
When you will have some progress I can test and debug with my hackrf...
Where can I send a donation?

Lawrence

[andre1968]

I have the chinese SDRplay (DE BG7YZF) with libmirisdr-4 from f3exv/libmirisdr-4. I made my own rx_sdrplay.cpp and rx_sdrplay.h because the original was not working. This come because mine sdr is not working synchonous. I make it like the rx_airspy manner. My question is about the 8 bit samples. What values expect the software? Is it from 0-225 or from -128-127?
Thank in advance.
Andre

[Oleg-Malyutin]

I am writing through a translator.
8-bit -127 128.
I strongly do not advise the driver. Had experience with a similar msi driver on Linux. This is reverse engineering and a lot of mistakes. I did not set the exact frequency.
Chinese SDRPlay should work well with native drivers (I have both the original and from China). I recommend a version no newer than 2.x.
Regards.
Oleg.

[andre1968]

Hello Oleg, Thank you for your quick response. I use this driver from https://github.com/f4exb/libmirisdr-4 [https://opengraph.githubassets.com/547824d9ba890242d9975c1068698e4a26f9dc156330d2d02c81cf7d49e4702d/f4exb/libmirisdr-4]<https://github.com/f4exb/libmirisdr-4> GitHub - f4exb/libmirisdr-4: Support of Mirics MSi001 + MSi2500 SDR devices<https://github.com/f4exb/libmirisdr-4> Support of Mirics MSi001 + MSi2500 SDR devices. Contribute to f4exb/libmirisdr-4 development by creating an account on GitHub. github.com For other projects I use also this driver. I think this works well. I didn't see mistakes because I hadn't made no many projects. Thank you very much. Andre

…

________________________________ Van: Oleg-Malyutin ***@***.***> Verzonden: donderdag 4 mei 2023 16:51 Aan: Oleg-Malyutin/sdr_receiver_dvb_t2 ***@***.***> CC: andre1968 ***@***.***>; Comment ***@***.***> Onderwerp: Re: [Oleg-Malyutin/sdr_receiver_dvb_t2] Crash on Fedora with SDRplay (Issue #4) I am writing through a translator. 8-bit -127 128. I strongly do not advise the driver. Had experience with a similar msi driver on Linux. This is reverse engineering and a lot of mistakes. I did not set the exact frequency. Chinese SDRPlay should work well with native drivers (I have both the original and from China). I recommend a version no newer than 2.x. Regards. Oleg. — Reply to this email directly, view it on GitHub<#4 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AHSZ4F73UPU6Z7YTFE3IS5TXEPM75ANCNFSM5H4VNUGQ>. You are receiving this because you commented.Message ID: ***@***.***>

[andre1968]

Hello Oleg,
What documents did you use? I'm reading this one: ETSI EN 302 755 V1.3.1 (2012-04). Have you used also other documents?
Andre

[Oleg-Malyutin]

Hello.
Yes, this document and more:

• ETSI TS 102 831

• "Improved synchronization, channel estimation,
  and simplified LDPC decoding for the physical
  layer of the DVB-T2 receiver"
  Doaa H Sayed 1* , Maha Elsabrouty 2 and Ahmed F Shalash 3

• "Optimum Receiver Design for Wireless
  Broad-Band Systems Using OFDM—Part I"
  Michael Speth, Student Member, IEEE, Stefan A. Fechtel, Member, IEEE, Gunnar Fock, and Heinrich Meyr, Fellow, IEEE

• "Optimum Receiver Design for OFDM-Based Broadband
  Transmission—Part II: A Case Study"
  Michael Speth, Stefan Fechtel, Gunnar Fock, and Heinrich Meyr, Fellow, IEEE

• "A Low-complexity Feed-forward I/Q Imbalance
  Compensation Algorithm"
  Niels A. Moseley and Cornelis H. Slump
  University of Twente
  Signals and Systems Group
  Department of Electrical Engineering
  Mathematics and Computer Sciences (EEMCS)
  Enschede
  The Netherlands

Regards.
Oleg.