As consumers demand more local content and as market pressures force broadcasters to show faster returns on investment, digital terrestrial broadcast (DVB-T) is the ideal end-to-end solution for broadcasters seeking to enlarge their market share without losing resources.
DVB-T utilises terrestrial based transmitters to allow broadcasters to deliver content directly to the home. By using a set-top box (STB) it is received with conventional UHF/VHF antennas.
In heavily built areas such as cities, analogue TV systems traditionally suffer from `multi-path echo signal` problems, commonly seen as `ghosting` effects on a TV screen. This is caused by reflected signals arriving at the receiving antenna at different times. DVB-T adds these various `out of phase` signals together to reassemble perfect pictures and sound.
One of digital TV`s great advantages over analogue TV is that it provides crystal clear terrestrial TV signals to moving receivers such as cars, buses and even handheld TV sets.
But DBV-T also has numerous other benefits.
First of all, it allows broadcasters to do local ad-insertion using existing bands. This means that they can offer data services, which is especially of value to the education market.
DVB-T makes the most of exciting bands by fitting up to five program streams into a single existing channel. It also provides affordable transmissions by using significantly less power for more transmissions - DVB-T can carry five digital channels in the space of one analogue channel - without compromising sound and picture quality.
One of the main drivers for using DVB-T is that it plays an important and complementary role in the delivery of fixed services where connection to cable and satellite systems is not possible or convenient.
And for those countries where cable dominates the television market, portable indoor reception offers an excellent opportunity for second and third television sets in a house. In that case, a STB, antenna and minimal installation cost is required.
There are two basic DVB-T network structures: Multiple frequency networks (MFN) and single frequency networks (SFN).
MFNs can provide for a large coverage area where the individual transmitters carry different programmes and allow for regional or local programming. MFNs can reproduce, approximately, the coverage of existing analogue networks. This may be of great importance if maintaining an existing coverage pattern such as a political or commercial requirement.
The SFN structure provides far more effective signal distribution within the coverage area - for the same number of transmitters and less power is needed to cover the same area (compared to an MFN). In a SFN, all the transmitters of a given programmed network use the same channel. The transmitters possess a common coverage area and cannot operate independently. They require high degree synchronisation: the signal broadcast from different transmitters must be identical in content; and must take place at the same time.
In Europe, broadcasters are already adopting DVB-T to provide market-wide and easy to deploy broadcasting solutions. By adopting DVB-T, local broadcasters can significantly increase the efficiency of their current offerings. They could utilise the opportunity to offer local content, local advertising as well as other broadband services such as distance learning and pay per view.
Share
Graphic Image Technologies is a media focused company operating in the digital video, advanced Web and multimedia environment.
The GIT Multimedia Bureau produces presentations, CD-ROMs and kiosks. In addition, it develops Web applications and provides database and e-commerce integration.
In the video arena, GIT is focused on offering a vast array of solutions, ranging from broadcasting video over satellite and ATM, to multicast applications for use in the corporate LAN and WAN and Internet streaming environments.
Editorial contacts