Digital TV Transmission

09Nov09

You might have probably heard about the fact that a lot of countries are switching off the analog TV signals and moving towards the “Digital TV transmission”. So what is it all about and how is it going to affect the end-users? But before we move on, let’s see why they are going for digital?

Why Digital?

If we compare analog signal with digital ones, the following are the advantages of digital signals:

– Less affected by the interference and noise

– Can be transmitted and copied without any defects (first copy and the 100^th copy will be exactly the same)

– Signal quality could be easily increased just by increasing the transmission speed

– Digital circuits are becoming cheaper

– Digital signal processing techniques are more advanced

– Enables the same TV coverage area with less power consumption

CD, VCD and DVD are just some examples of the mediums those have been converted to digital so far. On the other hand, cameras, TV transmitters, Radio transmitters and etc are examples of the mediums which are in the process of going digital. So it seems like analog is losing the war against digital. The features of digital signal are obvious but what about the benefits? (The following benefits are compiled from [1])

Benefits for Broadcasters?

– Depending on the compression rates, the broadcasters can have 4 to 10 SDTV (Standard Definition) channels or 1 HD TV (High Definition) compared to only 1 analog channel.

– Easy and secure encryption of channels

– Easier “video-on-demand” and “Pay TV” services.

– With the SFN (Single Frequency Network) technology different transmitters broadcasting over the same frequency will strengthen each other instead of interfering which will lead to a more effective usage of frequencies

Benefits for Viewers?

– Better video and audio quality (not experienced all the time since the broadcasters prefer to compress their signals in order to broadcast the maximum number of channels instead of HD-TV channels)

– Interactive video and data services that are not possible with analog technology

– More options since there is the possibility to have up to 10 digital channels compared to 1 analog channel on the same spectrum

Seems like the benefits of digital TV transmission will be mostly reaped by the broadcasters who will be able to have more channels that will increase their advertisement revenues and market base and the government bodies which will be able to free up the broadcast spectrum and sell it to other more profitable businesses.

What is needed for DTV Picture Reception Over-The-Air?

“You need one of the following:

A TV set with a digital tuner.

An analog TV set connected to a digital-to-analog converter box.

In either case, you will need an appropriate antenna connected to the TV set or the converter box; either an outdoor rooftop antenna or an indoor antenna (such as “rabbit ears” for VHF reception and a loop or bowtie for UHF reception).

If you have a digital TV set, you will not need any additional equipment (with the exception of an antenna) to receive over-the-air digital broadcast programming. However if you have an analog TV set, a digital converter box must be connected between the antenna and the analog TV to receive and display over-the-air digital programming.” [2]

DVB-T Market Deployment

DVB-T services are on air in more than 35 countries where more than 90 million receivers have been sold. The most successful markets, with DVB-T receivers readily available for less than EUR 30, include the UK, Germany, France, Spain, Italy and Australia. (See Figure 1.) Each year sees the launch of services in more countries and there are trial broadcasts on air across the world. [3] (See the figure below)

Digital TV

Figure 1 – Countries in Digital Transition

Situation in Sweden

Digital TV has been available in Sweden since 1999 and the analogue switch-off was completed on 15th October 2007 [4]. As Sweden is known for the high-tech savvy users, it is no surprise that it was one of the first countries to embrace the digital television.

Situation in Turkey

“Digital Terrestrial TV tests have been carried out since 2006 in Turkey. It is expected to have 95% of the country covered until 2014. When the digital TV reception is over %80 of the total population, there will be an extra-time announced for the analog switch of which is expected to take place in 2015. “[5]

Conclusion

– Analog broadcasting is coming to an end

– TV and computer are converging.

– The TV in your living room is becoming more of a “two-way communicator” instead of a “one-way receiver”

– We will see a lot of interesting interactive services in the near future

– Digital transmission will create a window of opportunity for the introduction of new technologies

References

1- “Dijital TV ve Multimedya” Prof. Dr. Avni Morgul Bogazici Universitesi Elektrik-Elektronik Muhendisligi Bolumu

2- http://www.dtv.gov/consumercorner.html, Last accessed 9-11-2009

3- DVB Fact Sheet – July 2009, http://www.dvb.org/technology/fact_sheets/DVB-T-Fact-Sheet.0709.pdf, Last accessed 9-11-2009

4- http://www.dvb.org/about_dvb/dvb_worldwide/sweden/, Last accessed 9-11-2009

5- http://www.ntvmsnbc.com , Last accessed 9-11-2009