Software Defined Radio is a method of replacing metal work (which is, in principle, healthy) with a programming headache. SDRs predict a great future and the main advantage is the removal of restrictions in the implementation of radio protocols. An example is the OFDM (Orthogonal frequency-division multiplexing) modulation technique, which has become possible only with the SDR technique. But there is another, purely engineering feature in SDR - the ability to control and visualize a signal at any arbitrary point with the least effort.
One of the interesting communication standards is terrestrial terrestrial television DVB-T2.
What for? Of course, you can just turn on the TV without getting up, but there is absolutely nothing to watch there and this is no longer my opinion, but a medical fact.
Seriously, DVB-T2 is designed with very broad capabilities, including:
There is experience in receiving digital television using the SDR principle. The DVB-T standard is included in the well-known GNURadio project. There is a gr-dvbs2rx block for the DVB-T2 standard (all for the same GNURadio), but it requires preliminary signal synchronization and it inspires (separate thanks to Ron Economos).
What we have.
There is an ETSI EN 302 755 standard that details transmission, but not reception.
On-air signal with a sampling rate of 9.14285714285714285714 MHz, modulated by COFDM with 32768 carriers, in a 8 MHZ band.
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- DVB-T2 .
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BBC ftp://ftp.kw.bbc.co.uk/t2refs/ .
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«pure SDR» .
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. . . , . — «Michael Speth, Stefan Fechtel, Gunnar Fock, Heinrich Meyr, Optimum Receiver Design for OFDM-Based Broadband Transmission – Part I and II». , , . . ( ) . . , OFDM .
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, DVB-T2. P1. P1 Technical Specification ETSI TS 102 831 ( ).
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, IQ imbalance, DC offset LO. , , SDR . , : QAM64 — . .
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QAM64 DVB-T2:
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- bit interleaving ( )
- cell interleaving ( )
- time interleaving ( )
- frequency interleaving ( OFDM )
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. (PLP).
— PLP «multiple», , , PLP «single» .
— PLP, PLP . , VLC, , .
DVB-T2 SdrPlay ( AirSpy.), -.
P.S. , PlutoSDR.
Someone will immediately say that there is only 6Msps for the IQ signal at the USB2.0 output, but at least 9.2Msps is needed, but this is a separate topic.