Digital TV: IP TV vs. DTH vs. Cable TVMonday, June 22, 2009 23:43
Update : This article has been published in a leading electronics magazine Electronics For you July’2009 edition.
Television is not a new concept. We are watching television for more than three decades. But, as everyone knows, technology is ever evolving which is leading towards the exponential changes in the world of television. With the advent of Digital TV, people got more choices to select the medium of their television viewing experience. Every one is going beyond terrestrial broadcast to get the best quality and enhanced television viewing experience.
There are three kinds of digital television broadcast systems existing today including Satellite TV, Digital Cable TV and IP TV (Internet Protocol Television) being the latest entrant in the world of television content broadcasting.
Internet Protocol Television (known widely as IP TV), being the newest arrival on the block, threatens the other two mediums by promising to give a tough competition. IP TV is a mechanism of viewing the regular television channels over IP. Similar to Satellite TV and Cable TV, the signal is encrypted using vendor specific security mechanisms and can only be decrypted by a receiver (STB). The video is sent in the form of IP packets over the existing broadband infrastructure and is assembled at the viewers’ end with the help of a Set Top Box. This becomes advantageous as existing broadband distribution infrastructure can be used to deliver television signals enabling the user to enjoy television over the same broadband connection used for surfing the internet. This is beneficial for broadcasters as they can offer “Triple Play” service of voice, data and television over the same network using the same infrastructure. “Triple Play” service refers to three different services of VoIP, Internet and IP-TV bundled together and offered over the same network. With IP TV, one can be assured of better video quality and stereophonic sound much like in case of DTH & Digital Cable TV. Even the customer specific services of Video on Demand (VOD) become a reality. Also, this enables broadcasters to have two way communications with the viewers as opposed to in case of DTH and Cable TV. IP –TV, still being in its stage of infancy, is not very stable. Due to high bandwidth requirement (approximately 5 Gbps, even ADSL2+ technology can support only up to 25 Mbps), hundreds of channels cannot be broadcasted simultaneously. Every channel change request by the user goes to the content server resulting in a delay for changing a channel. Currently, IP-TV is in roll out phase with broadcasters being BSNL, MTNL, Airtel and Reliance only in selected cities of India.
IP – TV has it own advantages but now, lets move on to Satellite TV (popularly known as DTH). In DTH, signal is received using a dish antenna installed at the user premises. The specifications of dish antenna may vary for each broadcaster with some broadcaster using bigger dish or varying the number of LNBs(Low Noise Blocks). This dish antenna receives the signal in encrypted form from the satellite and is installed with in direct line of sight of the satellite. Also, a Set Top Box (STB) is placed inside the viewer’s home. From this antenna, RG-6 coaxial cable connects the STB for signal transmission. This STB works only after a particular signal quality & strength is achieved which is fine tuned by using signal meter while installing the dish antenna. As in the case of Cable TV, STB receiver is used to decrypt the signal and enable the viewer to watch TV. In case of DTH, the content is direct controlled by the broadcaster and enables the viewer to pay and view the channels/bouquets as per his requirements. Similarly, the advantages of DVD quality signal and stereo sound are implicitly available to the viewer. The major advantage comes in the form of signal being available 24/7 as there is no intermediate operator between the broadcaster and the viewer unlike IP TV or Digital Cable TV. Various DTH broadcasters in India are Tata Sky, Bharti Airel, Sun Direct, DD Direct, Reliance Big TV, and Dish TV.
Satellite TV or DTH seems very promising and is quite a but successful in getting hold of market share but Cable TV is still on top claiming the highest numbers of subscribers to itself. Cable TV was one of the very early systems deployed worldwide against the traditional terrestrial system. It started with the analog systems in place. The signals from the various satellites were received at the Multi System Operator (MSO) end with the use of multiple high end dish antennas. These signals were then multiplexed at MSO end and then, transmitted to homes using coaxial cables. These signals were amplified by placing signal amplifiers at strategic points in the cable network. The whole network was managed by distributors authorized by MSO according to the area divisions. But as the signals were analog and were transmitted in a clear format, a lot of noise used to get added over the network before it reached the end user. Also, Signals were stolen by placing hooks on the wire adding to a lot of noise. This made life miserable for those who paid these MSO’s on a regular basis for the services. Now, that the Digital Cable TV is in place with broadcasters, Cable TV viewing experience is much different from what it used to be in case of Analog Cable TV as mentioned earlier. With Digital Cable TV, the user needs to install a Set Top Box (STB) at home and has a luxury of choosing channels/bouquets as per his requirements. The major advantage comes in the form of crystal clear Video and stereo audio. The signal distribution model still remains the same. But the signal is now encrypted and can only be decrypted by STB. So, even if someone tries to form a signal leakage point, it is of no use as the signal is nothing but a noise without subscription from MSO. The leading Cable TV broadcasters in India are Den Networks, Hathway & DigiCable.
As we discussed about the three different mediums of Television viewing, the major difference lies in the broadcast medium. All the three mediums need altogether different kinds of headend systems. These headend systems ensure that the signal is encrypted correctly and control the complete broadcast. These headend systems track the users for their viewing needs. The architecture of these headends varies completely from each other and the implementation is very much specific to technology solution providers like NDS & Nagravision.
As a viewer, we need to keep the following points in mind before subscribing to one particular medium of television viewing.
Uninterrupted Signal : This is first and foremost need for television viewing. Every system is useless if we do not have continuous signal available. The signal availability depends on the medium of broadcast. Generally, the least signal interruption occurs in case of Satellite TV as the signal is received directly from the Satellite to the viewer’s home. Where as in case of Cable TV, the intermediate area operators’ set up faults or failures can cause disruption in signals which is quite possible given the power supply scenario is most parts of India. IP TV network also suffers due to ongoing construction works in the neighborhoods resulting in coaxial cable disruptions and thus, switching off the whole Triple Play Network. But in case of Satellite TV signal, nature plays an important role. Signal outage occurs in case of DTH due to heavy rains, storms etc. So, If you live in an area prone to heavy rainfalls or storms, Satellite TV is not for you.
Customer Service: One major deciding factor should be the customer service provided by the broadcaster. As we need to use different services, easy access to these services is a must.
STB Software reliability: As everyone is aware, all the receivers (STBs) work using a software, this software needs to be reliable. Make sure that you have done enough review of a product before subscribing to it.
Signal Quality: As the three broadcast mediums are different, Signal quality also might vary. Although, the quality of audio/video does not differ drastically, but still the noise can get added to Cable and IP TV broadcast mediums in particular areas making signals problematic.
Network Infrastructure: As I mentioned earlier, this is most important consideration for IP TV requirements. Technically, IP TV requires a huge bandwidth to make TV viewing experience seamless which is still a deterrent in India. This will deteriorate more once the HDTV channels come into focus. Although broadcasters are claiming to offer high speed internet services, it is still seen that required speed is not available in most parts of India.
Services Offered: All the three broadcast mediums being different, the services offered by the broadcasters vary very widely. IP TV is much more suitable to the needs if you require Video on Demand much frequently. Also, Electronic Program Guides (EPGs) flexibilities and accuracy should be a consideration.
Cost: In the end, cost will definitely be a deciding factor. All the three different mediums cause the cost to vary to extremes. Cable TV is still the cheapest option as the existing network infrastructure is being used to deliver the signals. Satellite TV costs are higher due to installation and packaging of channels varying with each service provider. IP TV seems to be cost effective only if “Triple Play” services to be used.
In a nutshell, the digital television industry is in its nascent stage in India with IP TV just being born. It takes a lot of infrastructure support to provide seamless digital and interactive television experience. Digital Cable TV and DTH have stabilized over a period of time. It will take some more time for IP TV in the coming years to prove its edge over the other two mediums. The Digital Television broadcasting technology is still evolving and it will get complex with the advent of Personal Video Recorders (PVRs) and High Definition content. And as every field of life has it, only the fittest will survive.Quote of the Day:"Too bad drinking scotch isn't a paying job or Kenny's dad would be a millionare!" -- Cartman