Paritosh Kumar, Broadcast Engineer, TV18. Paritosh Kumar, Broadcast Engineer, TV18
DTH offers much better quality picture than cable TV. This is because cable TV in India is analog. Despite digital transmission and reception, cable transmission is still analog. DTH offers stereophonic sound effects. It can also reach remote areas where terrestrial transmission and cable TV have failed to penetrate.
Nowadays television plays an important role in our life. First of all, CRT televisions were introduced, but now they have been replaced by smart televisions. In the 1920s, when amplification made television practical, Scottish inventor John Logie Baird employed the Nipkow disk in his prototype video system. On March 25, 1925, Baird gave the first public demonstration of televised silhouette images in motion at Selfridge's Department Store in London.
Similarly, now cable has been replaced by DTH – all we know that DTH is used in high-quality picture resolution. Cable TV operators and DTH service providers have opposed a move by the telecom regulator to introduce interoperability of set-top boxes (STBs). Interoperability would allow users to change the TV service provider without having to change the set-top box or dish antenna. This is similar to the number portability introduced in the mobile service segment.
However, DTH players claim that it is not feasible to introduce interoperability. Reliance Digital TV says that if it was possible to develop an interoperable box, no DTH operator would have ever invested in manufacturing, selling, and installation of their own boxes.
First of all, we have to understand what is DTH. DTH stands for direct-to-home television. DTH is defined as the reception of satellite programs with a personal dish in an individual home. DTH does away with the need for the local cable operator and puts the broadcaster directly in touch with the consumer. In the cable system, only cable operators can receive satellite programs and they then distribute them to individual homes.
We have to understand how DTH works. It is important because we are discussing about cable networks and DTH. So, we have to know how both (cable and DTH) work one by one. A DTH network consists of a broadcasting center, satellites, encoders, multiplexers, modulators, and DTH receivers. A DTH service provider has to lease Ku-band transponders from the satellite. The encoder converts audio, video, and data signals into a digital format and the multiplexer mixes these signals. At the user end, there is a small dish antenna and set-top box to decode and view numerous channels. On the user's end, receiving dishes can be as small as 45 cm in diameter. DTH is an encrypted transmission that travels to the consumer directly through a satellite. DTH transmission is received directly by the consumer at his end through a small dish antenna. A set-top box, unlike the regular cable connection, decodes the encrypted transmission. Encryption is of utmost importance during the telecast so that no one else could relay the transmission.
As a comparison between these two, i.e., cable and DTH, it is more important to know which one is better.
It is true that DTH offers much better quality picture than cable TV. This is because cable TV in India is analog. Despite digital transmission and reception, cable transmission is still analog. DTH offers stereophonic sound effects. It can also reach remote areas where terrestrial transmission and cable TV have failed to penetrate. Apart from enhanced picture quality, DTH also allows for interactive TV services such as movie-on-demand, Internet access, video conferencing, and e-mail.
Cable television was invented by John Walson Sr. (1915–1993), from Mahanoy City, Pennsylvania, who is recognized by the US Congress and the National Cable Television Association as having invented cable TV in the spring of 1948. The abbreviation CATV is often used for cable television. It originally stood for Community Access Television or Community Antenna Television. Terrestrial television in India started with experimental telecast starting in Delhi on September 15, 1959 (official launch date) with a small transmitter and a makeshift studio. The regular daily transmission started in 1965 as a part of All India Radio.
Cable television is a system of delivering television programs to paying subscribers via radio frequency (RF) signals, transmitted through coaxial cables, or in more recent systems, light pulses through fiber-optic cables. This contrasts with broadcast television, in which the television signal is transmitted over the air by radio waves and received by television antenna attached to the TV.
The earliest cable systems were, in effect, strategically placed antennas with very long cables connecting them to subscriber's television sets. Because signal from the antenna became weaker as it travelled through the length of the cable, had to be inserted amplifiers at regular intervals to boost the strength of the signal and make it acceptable for viewing. Limitations in these amplifiers were a significant issue for cable system designers in the next three decades. In a cable system, the signal might have gone through 30 or 40 amplifiers before reaching the consumer, one every 1000 feet or so. With each amplifier, noise and distortion increases. Also, if one of the amplifiers failed, the picture is lost. Cable acquired the reputation of not having the best-quality picture as also not being reliable.
A cable network's quality depends on cable and other losses, or if digital is available on the same, then the quality will be good. As interactivity is concerned, it is the same as quality dependency whereas cable signal has potential to incorporate bi-directional communication, so interactivity can be easily achieved. On the other hand, DTH is digital mode so it is not dependent on things like cables, etc. So its quality and interactivity is good but this is a satellite transmission and it is also one direction; so information cannot be interactive on the same communication channel.
Generally, in a few months IPTV is likely to be introduced in India, but the term IPTV should not be confused with the delivery of television over Internet (for example watching YouTube videos or live channels like NDTV on your PC or mobile handset over your broadband connection). At the head end, content like Live TV channels is picked up from various sources like the satellite, and decrypted. The content is then compressed into a digital format like MPEG-2 or MPEG-4. Multiple programs or channels or sources like this are then packed into a single transport stream (MPEG2-TS) and packetized into IP packets to be multicast over the IP network. The IP packets reach the home through a broadband access like DSL, where a splitter is used to separate out the TV from regular broadband. TV channels are played out through the set-top box, which is programmed to listen to multicast channels, depending on which channel it is tuned to, or the unicast stream for video-on-demand. It provides the interactive interface to allow the user to navigate different live channels, video-on-demand, movies, games, etc. In case of multiple set-top boxes and PCs to view the programs, a home gateway can be used. Protocols like DLNA are used for networking within the home.