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DVB-T (Digital Video Broadcasting)

DVB-T (Digital Video Broadcasting) is a pan-European broadcasting standard (ETS 300 744) for digital terrestrial television. DVB-T is directly compatible with MPEG2-coded TV-signals in accordance with ISI/ OEC 13 818. The introduction of this digital service is already in progress in various European countries . Modulator and demodulator were developed in our company within the scope of custom specific development..

Areas of Application

  • DVB-T digital terrestrial television
  • portable reception
  • mobile reception

Setup

The DVB-T standard was developed according to the already standardised systems of cable and satellite transmission. The applied error protection was realised in analogy with the DVB-S standard. The Inner Interleaver was added which distributes the frequency selective interferences occurring in the radio field to numerous data symbols. Therefore, the error correction in the receiver is able to work more effectively.

The components following thereon were developed specifically for the DVB-T transmission system: firstly, the OFDM-frame was generated by summarising and positioning data payload and pilot carriers to OFDM symbols.A number of OFDM symbols are combined to an OFDM frame. The DVB-T standard determines FFT-length of 2k and 8k. Thus, an OFDM-symbol consists of 2k or 8k sub-carriers respectively. However, not all of them can be used for data transmission. A number of the sub-carriers are used either for the spectral limitation of the transmission signal or for the transmission of pilot information. In accordance with the IFFT-calculation, each OFDM-symbol is by the guard-interval.

The chart below shows the essential elements of DVB-T:

DVB-T

Technical characteristics

Different modulation types and channel coding rates give the system high adjustment ability to different channel profile requirements. The standard enables both the transmission of high data rates in radio channels with less interference as well as mobile reception (e.g. in the car or train) at reduced net data rate.

The following parameters can be set:

Amount of sub-carriers:
2k or 8k
Guard-Interval-Lengths:
1/4, 1/8, 1/16, 1/32
FEC-Coderates:
1/2, 2/3, 3/4, 5/6, 7/8
Modulation:
QPSK, 16QAM, 64QAM