Re: DVB-T receiving

[Ron Economos]

A couple of things.

1) If you're capturing at 10 Msps, you need to resample to the DVB-T 
sample rate of 9.142857 Msps. You can do that with a rational resampler 
block set to interpolation = 64 and decimation = 70.


2) That's not a very good signal. It has a lot of multipath and poor SNR.

Ron

On 2/15/22 09:04, Szilassi Andras wrote:

Hello,

Once again I am asking for some help with the DVB-T functionality of 
GNU radio.


I am using complex binary files recorded with a USRP at 10 Ms/s. The 
DVB-T rx example chain can't decode it at all. I have changed every 
setting according to Hungarian transmit parameters (64QAM, 1/4 GI, 3/4 
code rate etc.).


I think the problem might be with symbol acquisition, but cant really 
confirm my suspicion.


Below you can see the signal I am talking about. Could it be that for 
this type of synchronization this SNR is not sufficient?


image.png

Thanks,
András Szilassi

Re: DVB-T receiving

[Dan CaJacob]

I don't know anything about DVB-T, but since this is a wide recording, is
there any chance you got overflows when recording it and thus have
discontinuities?

On Tue, Feb 15, 2022 at 12:10 PM Szilassi Andras 
wrote:

> Hello,
>
> Once again I am asking for some help with the DVB-T functionality of GNU
> radio.
>
> I am using complex binary files recorded with a USRP at 10 Ms/s. The DVB-T
> rx example chain can't decode it at all. I have changed every setting
> according to Hungarian transmit parameters (64QAM, 1/4 GI, 3/4 code rate
> etc.).
>
> I think the problem might be with symbol acquisition, but cant really
> confirm my suspicion.
>
> Below you can see the signal I am talking about. Could it be that for this
> type of synchronization this SNR is not sufficient?
>
> [image: image.png]
>
> Thanks,
> András Szilassi
>
>

-- 
Very Respectfully,

Dan CaJacob

Changes with multiple sinks

[stephen.berger.temconsulting]

I am running the ATSC Transmitter flowgraph that is included with some
GNURadio compilations.  I am connecting the output to a HackRF, using the
Soapy HackRF Sink and monitoring the results on my spectrum analyzer.  I
also have the QT GUI Frequency Sink connected.  When I run using either sink
alone I get a nice ATSC signal either displayed or on my spectrum analyzer.
However, if I enable both sinks at the same time the waveform changes in the
display and what the HackRF puts out is radically different.  Why is this?
Is there a way to have the display as a monitor and get an undistorted
output from the HackRF?

 

Best Regards,



Stephen Berger

TEM Consulting, LP

Web Site -   www.temconsulting.com 
E-MAIL -   stephen.ber...@ieee.org
Phone -   (512) 864-3365
Mobile -   (512) 466-0833
FAX -   (512) 869-8709

 



uhd_atsc_tx_v2 - HackRF.grc
Description: Binary data

DVB-T receiving

[Szilassi Andras]

Hello,

Once again I am asking for some help with the DVB-T functionality of GNU
radio.

I am using complex binary files recorded with a USRP at 10 Ms/s. The DVB-T
rx example chain can't decode it at all. I have changed every setting
according to Hungarian transmit parameters (64QAM, 1/4 GI, 3/4 code rate
etc.).

I think the problem might be with symbol acquisition, but cant really
confirm my suspicion.

Below you can see the signal I am talking about. Could it be that for this
type of synchronization this SNR is not sufficient?

[image: image.png]

Thanks,
András Szilassi

Re: Low sample rate hardware

[vitt...@pm.me]

Thanks everybody for all the suggestion!
I think that modyfing an audio card it's the cheapest and more-than-enough 
solution at the moment ;-)

Vittorio

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