Digital Video Broadcasting – Terrestrial (DVB-T) is a system designed for the terrestrial transmission of digital television signals using ground-based transmitters. DVB-T is part of the DVB Project’s family of standards. Like other DVB standards, it relies on the transmission of data containers. These data containers are carried within the same 8 MHz (or sometimes 7 or 6 MHz) radio channels that were traditionally used for analog television broadcasts.

Key features and characteristics of DVB-T include:

1. Data Containers: DVB-T transmits data containers that can carry a flexible combination of MPEG-2 video, audio, and data. Within these containers, multiple television programs, radio broadcasts, or data services can be included. These data streams are combined in what is known as a multiplex. Each container contains Service Information (SI), providing details about the broadcasted programs. A single 8 MHz analog television channel can be used to transmit approximately 3-6 television programs simultaneously.
2. Decoder or Set-Top-Box: To receive DVB-T broadcasts, a decoder or set-top-box is required. The decoder receives the transmitted signal and decodes the compressed video, making it compatible with standard television sets.
3. Transmission Technology: DVB-T employs Coded Orthogonal Frequency Division Multiplexing (COFDM) for signal transmission. COFDM utilizes a large number of carriers, with each carrier responsible for transmitting a portion of the total data. These carriers are modulated using techniques like Quadrature Phase Shift Keying (QPSK) or Quadrature Amplitude Modulation (QAM). COFDM’s advantage lies in its robustness against issues like multipath reception and frequency-selective fading. To achieve this robustness, a “guard interval” is included, during which no data is transmitted, reducing overall transmission capacity.
4. Single Frequency Networks (SFN): DVB-T allows for the creation of SFNs, where overlapping networks of transmitter stations use the same frequency. This approach extends coverage areas. In overlapping areas, the weaker signal is treated as an echo due to multipath reception. However, synchronization is necessary, and echoes must fall within the guard time. If transmitter stations are far apart, significant time delays between signals can occur, requiring a larger guard interval.
5. Transmission Modes: DVB-T offers two COFDM transmission modes: a 2k mode with 1705 carriers and an 8k mode with 6817 carriers. The 2k mode is suitable for single transmitter operation and smaller single frequency networks with limited transmission power. The 8k mode is versatile and can be used for both single transmitter operation and large-area single frequency networks. The choice of guard interval is selectable.
6. Portable and Mobile Reception: DVB-T supports portable and mobile reception, with the possibility of mixing reception modes. Hierarchical transmissions enable one of the modulated streams (High Priority or HP stream) to receive higher error protection for mobile reception, while the other (Low Priority or LP stream) has lower protection. The higher protection mode sacrifices net bit rate for increased mobile reliability.
7. DVB-H Variant: DVB-T served as the basis for the development of DVB-H, a variant optimized for mobile reception on handheld devices.

In summary, DVB-T is a digital television broadcasting standard designed for terrestrial transmission. It offers flexible data containers, robust transmission technology, and the ability to create single frequency networks. DVB-T supports a variety of reception scenarios, including portable and mobile devices, and has influenced the development of DVB-H for handheld portables.