Ultra-cheap SDR Digital Television Transmission: ISDB-T with an - - PowerPoint PPT Presentation
Ultra-cheap SDR Digital Television Transmission: ISDB-T with an osmo-fl2k and an RTL-SDR Federico Larroca, Pablo Flores Guridi, David Artenstein, Lucas Ingls and Gastn Morales Instituto de Ingeniera Elctrica, Facultad de Ingeniera,
Federico Larroca, Pablo Flores Guridi, David Artenstein, Lucas Inglés and Gastón Morales
Instituto de Ingeniería Eléctrica, Facultad de Ingeniería, Universidad de la República, Uruguay
10th Annual GNU Radio Conference
September 16th 2020
■ Plenty of Digital TV standards: ATSC, DTMB, DVB-T, ISDB-T
DVB-T ATSC ISDB-T DTMB
2/19
■ Plenty of Digital TV standards: ATSC, DTMB, DVB-T, ISDB-T ■ ISDB-T → ISDB-T International (ISDB-Tb)
DVB-T ATSC ISDB-T DTMB
2/19
■ Although there are many benefits in the DTV Transition...
(a) PAL (b) ISDB-T
3/19
■ Although there are many benefits in the DTV Transition...
⇒ Improved audio/video quality ⇒ $$$(Digital Dividend) (a) PAL (b) ISDB-T
3/19
■ Although there are many benefits in the DTV Transition...
... the job is far from completed.
4/19
■ Back in 2016 we presented gr-isdbt: an open and free receiver for ISDB-T
implemented in GNU Radio
5/19
■ Back in 2016 we presented gr-isdbt: an open and free receiver for ISDB-T
implemented in GNU Radio
■ We are now presenting the “completion” of the project: an SDR-based open source
ISDB-T transmitter
■ What for?
5/19
■ Back in 2016 we presented gr-isdbt: an open and free receiver for ISDB-T
implemented in GNU Radio
■ We are now presenting the “completion” of the project: an SDR-based open source
ISDB-T transmitter
■ What for?
the DTV transition
5/19
1
Introduction
2
The ISDB-T Standard
3
Our Implementation
4
Ultra-cheap setup: osmo-fl2k
5
Conclusion
6/19
■ Stands for Integrated Services Digital Broadcasting - Terrestrial ■ Japanese digital and terrestrial television standard, based on DVB-T ■ Adopted and adapted by Brazil:
■ New version of the standard was named ISDB-Tb ■ ISDB-Tb was lated adopted by most of South American countries
7/19
TS REMUX
RS(204,188) Hierarchical division Energy dispersal Energy dispersal Energy dispersal Byte interleaving Byte interleaving Byte interleaving Convolutional encoder Convolutional encoder Convolutional encoder Bit interleaving Bit interleaving Bit interleaving Mapping Mapping Mapping Hierarchical combination Time interleaving Frequency interleaving TMCC signal Pilots OFDM frame structure IFFT GI insertion
Parameters Values Modulation BST-OFDM, with CP Total Bandwidth 6 MHz Number of segments 13 Segments bandwidth 6000/14 ≈ 428.57 kHz Number of carriers mode 3: 8192, active: 5617 (432 per segment) mode 2: 4096, active: 2809 (216 per segment) mode 1: 2048, active: 1405 (108 per segment) Sampling rate 512/63 ≈ 8.126MHz Cyclic Prefix duration 1/4, 1/8, 1/16, 1/32 (of active symbol duration) 252 µs (mode 1) Active symbol duration 504 µs (mode 2) 1004 µs (mode 3) Convolutional Code Rate 1/2, 2/3, 3/4, 5/6, 7/8 0, 1, 2, 4 (mode 1) Time interleaving parameter 0, 2, 4, 8 (mode 2) 0, 4, 8, 16 (mode 3) Modulation schemes DQPSK, QPSK, 16QAM, 64 QAM
8/19
TS REMUX
RS(204,188) Hierarchical division Energy dispersal Energy dispersal Energy dispersal Byte interleaving Byte interleaving Byte interleaving Convolutional encoder Convolutional encoder Convolutional encoder Bit interleaving Bit interleaving Bit interleaving Mapping Mapping Mapping Hierarchical combination Time interleaving Frequency interleaving TMCC signal Pilots OFDM frame structure IFFT GI insertion
■ (up to) three Transport Streams
(Layers in ISDB-T lingo) transmitted at the same time
■ Each Layer may use its own set
■ Since the MPEG TS cannot be
used for hierarchical transmissions, ISDB-T defines the so-called Broadcast Transport Stream (BTS)
Parameters Values Modulation BST-OFDM, with CP Total Bandwidth 6 MHz Number of segments 13 Segments bandwidth 6000/14 ≈ 428.57 kHz Number of carriers mode 3: 8192, active: 5617 (432 per segment) mode 2: 4096, active: 2809 (216 per segment) mode 1: 2048, active: 1405 (108 per segment) Sampling rate 512/63 ≈ 8.126MHz Cyclic Prefix duration 1/4, 1/8, 1/16, 1/32 (of active symbol duration) 252 µs (mode 1) Active symbol duration 504 µs (mode 2) 1004 µs (mode 3) Convolutional Code Rate 1/2, 2/3, 3/4, 5/6, 7/8 0, 1, 2, 4 (mode 1) Time interleaving parameter 0, 2, 4, 8 (mode 2) 0, 4, 8, 16 (mode 3) Modulation schemes DQPSK, QPSK, 16QAM, 64 QAM
8/19
TS REMUX
RS(204,188) Hierarchical division Energy dispersal Energy dispersal Energy dispersal Byte interleaving Byte interleaving Byte interleaving Convolutional encoder Convolutional encoder Convolutional encoder Bit interleaving Bit interleaving Bit interleaving Mapping Mapping Mapping Hierarchical combination Time interleaving Frequency interleaving TMCC signal Pilots OFDM frame structure IFFT GI insertion
■ OFDM with configurable number
■ Each Layer is sent over a set of
particular carriers
■ Carriers are partitioned into
Segments
Segment 0 Segment 1 Segment 2 Segment 3 Segment 5 Segment 7 Segment 9 Segment 11 Segment 4 Segment 6 Segment 8 Segment 10 Segment 12
6 MHz channel
Layer B Layer A (1-seg)
Parameters Values Modulation BST-OFDM, with CP Total Bandwidth 6 MHz Number of segments 13 Segments bandwidth 6000/14 ≈ 428.57 kHz Number of carriers mode 3: 8192, active: 5617 (432 per segment) mode 2: 4096, active: 2809 (216 per segment) mode 1: 2048, active: 1405 (108 per segment) Sampling rate 512/63 ≈ 8.126MHz Cyclic Prefix duration 1/4, 1/8, 1/16, 1/32 (of active symbol duration) 252 µs (mode 1) Active symbol duration 504 µs (mode 2) 1004 µs (mode 3) Convolutional Code Rate 1/2, 2/3, 3/4, 5/6, 7/8 0, 1, 2, 4 (mode 1) Time interleaving parameter 0, 2, 4, 8 (mode 2) 0, 4, 8, 16 (mode 3) Modulation schemes DQPSK, QPSK, 16QAM, 64 QAM
8/19
TS REMUX
RS(204,188) Hierarchical division Energy dispersal Energy dispersal Energy dispersal Byte interleaving Byte interleaving Byte interleaving Convolutional encoder Convolutional encoder Convolutional encoder Bit interleaving Bit interleaving Bit interleaving Mapping Mapping Mapping Hierarchical combination Time interleaving Frequency interleaving TMCC signal Pilots OFDM frame structure IFFT GI insertion
■ Sampling rate is fixed ■ Cyclic prefix is configurable ■ Resulting rates:
Parameters Values Modulation BST-OFDM, with CP Total Bandwidth 6 MHz Number of segments 13 Segments bandwidth 6000/14 ≈ 428.57 kHz Number of carriers mode 3: 8192, active: 5617 (432 per segment) mode 2: 4096, active: 2809 (216 per segment) mode 1: 2048, active: 1405 (108 per segment) Sampling rate 512/63 ≈ 8.126MHz Cyclic Prefix duration 1/4, 1/8, 1/16, 1/32 (of active symbol duration) 252 µs (mode 1) Active symbol duration 504 µs (mode 2) 1004 µs (mode 3) Convolutional Code Rate 1/2, 2/3, 3/4, 5/6, 7/8 0, 1, 2, 4 (mode 1) Time interleaving parameter 0, 2, 4, 8 (mode 2) 0, 4, 8, 16 (mode 3) Modulation schemes DQPSK, QPSK, 16QAM, 64 QAM
8/19
■ Handheld receivers were a priority in ISDB-T design
9/19
■ Handheld receivers were a priority in ISDB-T design ■ 1-seg: if so configured the central segment may be received on its own
Segment 0 Segment 1 Segment 2 Segment 3 Segment 5 Segment 7 Segment 9 Segment 11 Segment 4 Segment 6 Segment 8 Segment 10 Segment 12
6 MHz channel
Layer B Layer A (1-seg)
9/19
■ Handheld receivers were a priority in ISDB-T design ■ 1-seg: if so configured the central segment may be received on its own
Segment 0 Segment 1 Segment 2 Segment 3 Segment 5 Segment 7 Segment 9 Segment 11 Segment 4 Segment 6 Segment 8 Segment 10 Segment 12
6 MHz channel
Layer B Layer A (1-seg)
9/19
1
Introduction
2
The ISDB-T Standard
3
Our Implementation
4
Ultra-cheap setup: osmo-fl2k
5
Conclusion
10/19
11/19
Takes a BTS and outputs the MPEG TS(s). Not really necessary on single-segment transmissions.
11/19
Relatively standard blocks, some of them already in GNU Radio.
11/19
Pilots and signaling are inserted.
11/19
OFDM modulation.
11/19
Normalization and transmission.
11/19
1
Introduction
2
The ISDB-T Standard
3
Our Implementation
4
Ultra-cheap setup: osmo-fl2k
5
Conclusion
12/19
■ We tested the implementation with some SDR transmitting-capable hardware
models (particularly USRP B200)
■ As receivers we used commercial TVs, as well as other SDRs including RTL-SDR dongles
(which receive the 1-seg portion only)
13/19
■ We tested the implementation with some SDR transmitting-capable hardware
models (particularly USRP B200)
■ As receivers we used commercial TVs, as well as other SDRs including RTL-SDR dongles
(which receive the 1-seg portion only)
■ However, we were particularly interested in testing the osmo-fl2k project.
13/19
■ An 15 $ USB-to-VGA adapter as an SDR transmitter?
1Checkout gr-tempest at https://github.com/git-artes/gr-tempest.
14/19
■ An 15 $ USB-to-VGA adapter as an SDR transmitter? ■ The basic idea is the same as with TEMPEST (a.k.a. Van Eck Phreaking)1...
1Checkout gr-tempest at https://github.com/git-artes/gr-tempest.
14/19
■ An 15 $ USB-to-VGA adapter as an SDR transmitter? ■ The basic idea is the same as with TEMPEST (a.k.a. Van Eck Phreaking)1...
... except that now it’s on purpose.
1Checkout gr-tempest at https://github.com/git-artes/gr-tempest.
14/19
■ On Fresco Logic’s FL2000 chip-based adapters all samples (including blanking)
are generated by the host PC.
■ The Osmo-fl2k team reversed engineering the USB protocol, disabled blanking and provide
the necessary software to send arbitrary samples to the USB adapter
15/19
■ On Fresco Logic’s FL2000 chip-based adapters all samples (including blanking)
are generated by the host PC.
■ The Osmo-fl2k team reversed engineering the USB protocol, disabled blanking and provide
the necessary software to send arbitrary samples to the USB adapter
■ The VGA signal’s spectrum (X(f )) looks like this:
The pulse (approximately rectangular) Fourier Transform The Discrete-Time Fourier Transform
The emitted spectrum.
Note that 1/Tp is typically below 150 MHz.
15/19
■ How to avoid the frequency nulls generated by the pulse every 1/Tp? fi
16/19
■ How to avoid the frequency nulls generated by the pulse every 1/Tp? Simply use
an intermediate frequency (beware of the harmonics)
fi
16/19
■ How to avoid the frequency nulls generated by the pulse every 1/Tp? Simply use
an intermediate frequency (beware of the harmonics)
■ Demo time!
USB-VGA adapter
VGA-BNC adapter
Monopole antenna Amplifier
16/19
1
Introduction
2
The ISDB-T Standard
3
Our Implementation
4
Ultra-cheap setup: osmo-fl2k
5
Conclusion
17/19
■ We presented gr-isdbt, a software-based, free and open ISDB-T transceiver. ■ We have successfully tested it using osmo-fl2k as transmitter.
18/19
■ We presented gr-isdbt, a software-based, free and open ISDB-T transceiver. ■ We have successfully tested it using osmo-fl2k as transmitter. However, some caveats:
equalize, but single-carrier schemes will be more challenging to use with osmo-fl2k.
18/19
■ We presented gr-isdbt, a software-based, free and open ISDB-T transceiver. ■ We have successfully tested it using osmo-fl2k as transmitter. However, some caveats:
equalize, but single-carrier schemes will be more challenging to use with osmo-fl2k.
wideband signals. Thus, up to the VHF band at most (demo was at 177 MHz and it was bordeline, even with the amplifier). Again: beware of the harmonics.
18/19
■ We presented gr-isdbt, a software-based, free and open ISDB-T transceiver. ■ We have successfully tested it using osmo-fl2k as transmitter. However, some caveats:
equalize, but single-carrier schemes will be more challenging to use with osmo-fl2k.
wideband signals. Thus, up to the VHF band at most (demo was at 177 MHz and it was bordeline, even with the amplifier). Again: beware of the harmonics.
(except for simple waveforms) is virtually impossible.
18/19
■ We presented gr-isdbt, a software-based, free and open ISDB-T transceiver. ■ We have successfully tested it using osmo-fl2k as transmitter. However, some caveats:
equalize, but single-carrier schemes will be more challenging to use with osmo-fl2k.
wideband signals. Thus, up to the VHF band at most (demo was at 177 MHz and it was bordeline, even with the amplifier). Again: beware of the harmonics.
(except for simple waveforms) is virtually impossible. ■ Future work:
single-carrier transmission or TV set dependent reception (if no BTS encoder is available).
gr-dtv.
18/19
19/19