Due to the numerous advantages of digital technology and above all the lack of available capacities, Slovenia switched to digital TV broadcasting in 2010. In addition to larger capacities, digital television networks also open possibilities for extra services as well as HD TV. The main advantage of digital television broadcasting lies in the fact that a transmitter does not transmit just one program on a certain frequency, but a digital package of programs – a multiplex.
Frequencies for Digital TV Networks
Frequencies are required for digital television networks. The same band of the radio frequency spectrum is used as was used for analog television, except for channels 61 and 69. In this part of the spectrum, television broadcasting is being abandoned due to the introduction of broadband mobile services in the broader European area (digital dividend). Due to the significantly different characteristics of digital broadcasting, television channels were reallocated at a conference in Geneva in 2006. A new frequency plan is now being used for digital TV broadcasting.
How to get frequencies?
Frequencies for digital television network can only be acquired via a public tender, through which the Agency allocates frequency bands (television channels) for single-frequency networks. Successful bidders receive decisions on the allocation of radio frequencies and become digital television network operators. They must provide transmission services (space in the multiplex) to all interested parties under equal conditions.
In tender conditions, the Agency prescribes several requirements, of which the transmitting technology (modulation) is the most important one. Currently the DVB-T system is in use in Slovenia (and also more broadly in Europe), and a newer version DVB-T2, which brings higher capacities and a more robust system, is being introduced. This system is already used in some European countries.
What can be placed in a multiplex?
The network operator is at the same time a multiplex operator, and must provide coding and multiplexing of channels. In its multiplex, an operator may transmit the radio and television programs which were granted the right for digital broadcasting in the network managed by the operator. This license can be acquired by interested program publishers through public tenders published by the agency.
Several TV programs can be placed in a multiplex by using compression. In Slovenia the advanced MPEG-4 system is used. The compression rate is usually agreed upon between the network operator and program publisher, and currently approximately 2 Mbit per frame suffices for high-quality transmission in standard definition.
HDTV channels can also be placed in a digital multiplex, however they take up a significantly higher share of the multiplex’s capacity. A multiplex’s capacity, which means the number of programs and services on it, depends on several technical parameters: modulation i.e. manner of transmitting, FEC, guard interval, etc. The Agency prescribes some technical parameters in the decision, while the operator may select others independently.
In addition to Free to Air programs, multiplexes also support the broadcasting of Pay TV. In this case the operator or program publisher does not need a license for digital broadcasting, and in such cases the operator usually provides digital receivers with integrated support for pay TV.
In addition to programs, a network operator may also transmit additional services, the most popular of which is the electronic program guide.