The DVB-T service was firstly implemented in United Kingdom in 1998. So far, DVB-T was deployed in more than 70 countries and the same number of countries decided for DVB-T2 which is able to broadcast standard, high, ultra-high definition and mobile TV and radio.
DVB-T/T2 services are aired terrestrially within the ultra-high frequency (UHF) band covering frequencies in a range from 300 MHz to 3 GHz [1]. They share the same band with analog TV therefore its deployment is dependent on releasing of frequencies occupied by analog television channels. An 8 MHz channel carrying single analog TV channel can carry within DVB-T several digital TV and radio channels with other information.
DVB-T technology can reuse the same infrastructure used by analog terrestrial television (the existing broadcasters and transmitters).
At the receiving side users have to buy a new end receiver that can be in the form of a standalone device (set-to-box) or as an integrated receiver decoder (IRD) in TV set.
Table 1 compares DVB-T with DVB-T2 [7].
New error correction codes: LDPC (Low Density Parity Check) combined with BCH (Bose-Chaudhuri-Hocquengham) enable DVB-T2 to transmit a very resistive signal. Both are based on OFDM (orthogonal frequency division multiplex) modulation with a large number of subcarriers (frequencies) which is very robust in a multipath propagation environment and both use bit, time and frequency interleaving. In general, DVB-T2 is very flexible because it offers a lot of modes.
OFDM places guard intervals between OFDM symbols what with a low symbol rate enable it to eliminate intersymbol interference. This principle also offers operators a possibility to create so called a single frequency network where transmitters broadcast a signal on the same frequency. DVB-T standards can incorporate a hierarchical modulation which is able to combine two separate transport streams for two different types of receivers into one DVB stream.
Parameters |
DVB-T |
DVB-T2 |
FEC |
Convolutional & Reed Solomon Coding - 1/2, 2/3, 3/4, 5/6, 7/8 |
LDPC + BCH 1/2, 3/5, 2/3, 3/4, 4/5, 5/6 |
Modulations |
QPSK, 16QAM, 64QAM |
QPSK, 16QAM, 64QAM, 256QAM |
Guard Interval |
1/4, 1/8, 1/16, 1/32 |
1/4, 19/128, 1/8, 19/256, 1/16, 1/32, 1/128 |
Number of subcarriers |
2k, 8k |
1k, 2k, 4k, 8k, 16k, 32k |
Bandwidth |
6, 7, 8 MHz |
1.7, 5, 6, 7, 8, 10 MHz |
Typical data rate |
24 Mbit/s |
40 Mbit/s |
Max. data rate (20 dB C/N) |
31.7 Mbit/s (using 8 MHz) |
45.5 Mbit/s (using 8 MHz) |
Required C/N ratio (24 Mbit/s) |
16.7 dB |
10.8 dB |