Cable television

Analog Cable TV Digitization

In Bhutan, after using analogue TV for more than 16 years, digitization of cable TV has been initiated 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 by connecting 60 out of 93 Local Cable Operators (LCOs) to two Multi-Service Operators (MSOs). The digitization of cable TV was expected to be completed by the end of the year 2022. Until then, there are many problems with the digitization process, such as people who do not want to switch to digital because people still don’t understand the difference between analog and digital cable. television services (CATV). There are people who are not sufficiently aware of the advantages of digital and therefore do not know why the set-top box (STB) is necessary and why the current analog is a problem. Despite all these problems, Bhutan has moved towards the provision of digital television services due to its many advantages over analogue.

Difference in setting up digital cable TV from analog

The analog signal is continuous in nature and there are different types of modulation (amplitude, phase and frequency modulation) in which the pattern of the carrier signal varies according to the changing signal level of the message signal. Analog CATV systems use vestigial sideband modulation which is a form of amplitude modulation in which a sideband is partially suppressed. 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 travels and is connected directly to the TV, requiring only one remote control to control the program.

Digital television uses quadrature amplitude modulation (QAM) techniques after compression. This gives advantages to digital modulation 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 such as an HDMI cable (high definition multimedia interface), a decoder and a remote control of the decoder. The coaxial cable is connected to the decoder and from the decoder the HDMI cable is connected to the TV. Finally, the program is switched using the set-top box remote after you put your TV in digital mode using HDMI as the source input.

The set-top box plays an important role in digital cable television because it allows users to view video content from specific Internet video providers by 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 want to use their analog TVs to receive digital broadcasts.

Analog Cable TV Setup

In analog television, the signal is directly received by the satellite dish which is connected to the receiver by 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 television had a number of problems some of the main ones being:

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

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

• Since the analog continues, the signals suffer from interference or loss of signal and therefore lead to poor video quality

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

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

Installation of digital television

In digital TV setup, unlike analog, it uses QAM as the modulation technique where the signal is digitized resulting in a more compressed signal and better quality on the consumer side. Also, with the creation of MSO, the requirement for a headend has decreased significantly. Multiple System Operator (MSO), also known as Multi-System Operator, is a designation often used for cable companies that offer services beyond television broadcasting. Many MSOs offer multiple internet and phone 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 public revenues.

Contributed by

BICMA