Cable television

Digitizing Analog Cable TV


In Bhutan, after using analog TV for over 16 years, the digitization of cable TV has been launched since June 2018 in consultation with local cable operators (LCOs) and other relevant stakeholders. Digitization started with Thimphu and now most parts of the country have already gone digital connecting 60 local cable operators (LCOs) out of 93 to two multi-service operators (MSOs). The digitization of cable TV was to be completed by the end of the year 2022. Until then, there are many issues related to the digitization process, such as people who do not want to go digital because people do not want to go digital. still not understand the difference between analog and digital cable. television services (CATV). There are people who are not sufficiently aware of the benefits of digital and therefore do not know why Set Top Box (STB) is needed and why current analogue is a problem. Despite all these problems, Bhutan has shifted towards providing digital TV services due to its many advantages over analog.

Difference in digital cable TV setup compared to analog

The analog signal by nature is continuous and there are different types of modulation (amplitude, phase and frequency modulation) in which the pattern of the carrier signal varies depending on the changing signal level of the message signal. Analog CATV systems use residual sideband modulation which is a form of amplitude modulation in which one sideband is partially removed. This reduces the bandwidth of the transmitted signal, allowing narrower channels to be used. In this case, we need a coaxial cable where the signal flows and is connected directly to the TV, requiring only one remote to control the program.

Digital television uses quadrature amplitude modulation (QAM) techniques after compression. This gives digital modulation advantages over analog modulation with available bandwidth, high noise immunity and power handling. This allows a TV station to broadcast more channels and more HD channels on the same airwaves, providing a wider variety of programs with better quality. In this case, we need additional devices like an HDMI (High Definition Multimedia Interface) cable, a set-top box and a set-top box remote control. The coaxial cable is connected to the set-top box and from the set-top box, the HDMI cable is connected to the TV. Finally, the program is switched using the decoder remote control after putting your television in digital mode using HDMI as the source input.

The set-top box plays an important role in digital cable television as it allows users to view video content from specific internet video providers while decoding digital television broadcasts. It is a device that allows a television to receive and decode digital television (DTV) broadcasts. It is necessary for consumers who wish to use their analog televisions to receive digital broadcasts.

Setting up analog cable TV

In analog television, the signal is directly received by the satellite dish which is connected to the receiver via a coaxial cable. The received signal is modulated using amplitude modulation techniques which is then multiplexed and distributed to an optical transmitter where the signal is transmitted as light to the receiver. On the other hand, it is also amplified and transmitted as an analog signal directly to the receiver. Modulation allows us to transmit a signal over a long distance where a high frequency carrier wave is used to transmit the low frequency message signal and the transmitted signal continues to have all the information contained in the original message signal. .

Challenges with the analog CATV system

Despite its popularity and reliability for decades, analog TV had a number of problems, the main ones of which were:

• No innovation and no technological upgrades in terms of offering various services such as Internet and data communications.

• Analogue cable television systems do not provide services such as video on demand, interactive television and games.

• Since analog is continuous, the signals experience interference or loss of signal and therefore lead to poor video quality

• Analogue cable television systems have difficulty regulating and determining the exact number of subscribers. As a result, losing revenue for the government in terms of taxes and license fees.

Therefore, the digitization of CATV has become necessary to provide better quality of services to each consumer as well as to MSOs and LCOs.

Implementation of digital television

In digital TV setup, unlike analog, it uses QAM as a modulation technique where the signal is digitized resulting in a more compressed signal and better quality on the consumer side. In addition, with the creation of MSOs, the need for the head end has decreased considerably. Multiple System Operator (MSO), also known as a multi-system operator, is a designation often used for cable companies that provide services beyond television broadcasting. Many MSOs offer several Internet and telephone services in addition to their cable TV offerings. Both MSOs are equipped with Conditional Access System (CAS) and Subscriber Management System (SMS) in which we can determine the actual number of subscribers at any given time as well as customize the type and number of channels distributed. to individual subscribers. . Thanks to this digital system, there will also be transparency in the collection of government revenue.

Contribution from

BICMA