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How TV Broadcast Works: A 101 Guide


Most millennials and Gen Zs don’t watch a lot of TV. They are usually busy staring at their smartphone or laptop screens. But, contrary to general perception, TVs did not fall out of favor. 

The television is still the primary display device to watch movies, shows, etc., for the majority. The number of new TVs getting released and the technological advancements made in recent times in the space indicate that.

Talking about what kind of content people watch on TV, traditional broadcasting is still supreme, although OTT (over-the-top) TV has covered significant ground in the past few years.

Some people only use TV to stream online content. They are mostly the younger crowd, who may have heard about traditional broadcasting and experienced it, but would likely not know how the thing works.

If you’re one of them and want to know the basics of TV broadcasting, this article is for you. Keep reading to get educated.

How are TV Signals Transmitted?

A TV signal

A TV signal is sent through traditional, cable, or satellite transmission processes.

Irrespective of the route taken, a set of elements/devices are needed for the transmitted signals to start their journey and reach you in your home as your favorite TV show or program.

The following is a breakdown of those elements:

Image and Audio Sources

An image source is the movie, show, or program you see on the TV. It’s recorded by a camera that converts the visuals into a signal.

Image and Audio Sources

In the past, TV cameras could only capture video in black and white. Later, cameras that could pick up discrete RGB (red, blue, and green) signals were made.

Without the camera and transmission systems capable of beaming color signals over the air, the color TVs we take for granted and enjoy today wouldn’t have been possible.

A TV show or news program requires an audio source captured by the microphone attached to the video camera. The audio could be mono, stereo, surround sound, etc.

TV Transmitter

TV Transmitter

A transmitter is needed to send the video and audio signals captured by the camera. These transmitters are found at a TV station, which receives the audio-video signals through a broadcaster. (More on broadcasters later.)

Television transmitters can simultaneously transport multiple signals or information for more than one TV channel. Both the image and audio are packaged as one signal to be decrypted by the receiver in a TV.

The TV transmitter can generate VHF (very-high frequency) or UHF (ultra-high frequency) electromagnetic spectrum bands. VHF stations have a more extensive geographical reach than UHF stations and are, therefore, more widespread.

TV Receiver

A receiver (found in your TV) accepts, demodulates, and decrypts transmitted TV signals channeled through an antenna. It converts the radio waves (video and audio signals) into signals that get processed into pictures and sound.  

Different TV channels get transmitted at a particular frequency. The receiver parses the data efficiently so that when you select a specific TV channel, the TV can display the same channel and not some random content.

Display and Sound Devices

Display devices

A display device, like your TV,  can convert the electrical signals accessed through the receiver into visible light. The display tech could be CRT, LCD, OLED, QLED, etc.

A sound device is your TV’s built-in speaker or the standalone speaker your TV is connected to. The device converts the electrical signals it receives into audio waves. The audio device allows your TV’s audio to play in sync with the video. 

There are different kinds of TVs, and how they receive the transmitted signals and output them as audio and video differ.

For instance, a CRT (cathode-ray tube) TV receives and sifts the signals as discrete audio and visual components.

The audio element travels to the TV’s audio circuit, comprising the loudspeaker that reproduces the original recorded audio. The video signal takes a separate route.

Traditional TV Broadcasting: An Overview

Traditional TV broadcast signals (video and audio) are transferred over the air as electromagnetic waves.

Broadcast TV is designed to be free of charge to its users. Anyone can freely capture and decrypt the signal data if they have an antenna connected to a TV with a receiver, provided they are within a broadcast transmitter’s range.

antenna to a TV

However, some TV stations may scramble the signal and charge people who want access to a descrambled signal.

TV stations that do not choose to bungle up the signal sell airwave time to advertisers, earning themselves the “commercial station” name.

And there are TV stations that neither mess with the signal nor sell air time to advertisers. These “non-commercial stations” make money through government or private entities’ donations.

They may even collaborate with businesses and give them a mention at the beginning and end of the program.

Broadcasters and TV Stations

TV broadcasting has a specific distribution flow. It’s comprised of the broadcaster, TV station, and others.

A television broadcaster or network, such as NBC and BBC, distributes TV programs to different TV stations. Television broadcasters can also have their own TV channels.

BBC Broadcaster

The TV network doesn’t make all of its content.

Production houses (such as Sony Pictures Television and Warner Bros. Television) often distribute content to the networks. And they could send their content to multiple networks, even the competing ones.

Certain TV broadcasters could import foreign TV programs, play archived content, or rerun programs to fill vacant slots.

TV broadcasters distribute their content to TV stations based on their geographic location. But, generally, the content is universal.

TV networks create both original content and play third-party movies and shows. A local TV station seldom produces its programs and relies on its network for content.

However, in certain instances, a local TV station could dish out region-specific content sourced from local producers.

TV stations broadcast their programs over public airwaves using a government-licensed digital spectrum. TV networks send the signals to TV stations using satellites.

A TV station could be an independent entity or partly or wholly owned by the broadcaster. A TV network could encompass multiple local TV stations.

The local stations not owned by a network are known as “network affiliates.”

How Do Cable and Satellite TVs Work?

Cable TV, unlike broadcast TV, doesn’t send information over the air.

As the name hints, it employs cables that span the distance between the cable service provider and the subscriber’s house.

Cable TVs

The cables are usually fiber optic or copper cords, and the signals transmitted could be digital or analog, similar to how electromagnetic broadcasting works. The lines are generally laid underground to avoid external harm.

The cable TV provider can modulate various TV programs onto the standard frequencies before transmitting them to the user’s property via a cable.

The cable TV mechanism, however, is prone to signal or cable service thefts, which the service providers try to mitigate by encoding the signal in complex ways.

The STB (set-top box) installed in the cable TV subscriber’s house decodes those signals so that the TV’s receiver can interpret them and take things forward. The decoding happens right before the user selects a particular channel on the TV.

The good thing about cable TV is it’s reliable and stable. Unlike satellite TV, it doesn’t get affected by weather and doesn’t require the internet, which can be pretty iffy at times or simply not speedy enough.

Cable TV only lets you down when there’s significant damage to the cable infrastructure, and the chances of that are pretty slim.

Satellite TV

Satellite TV

Satellite TV shuns airwaves and cables and heads straight to space.

Your satellite TV service provider sends TV signals to the in-space satellite. The signal is then transmitted from the satellite to a large dish-like antenna set up on the roof of your house.

The satellite antenna receives the encoded or unencoded signals and sends them to the set-top box connected to the TV. The STB receives the signal, interprets the data if needed, and routes them to particular channels.

The dish antenna must point to a specific satellite in space for satellite TV to work, which is taken care of at the time of installation by the satellite TV service provider.

To learn more about how satellite TV works, watch this video:

How does Satellite Television work? | ICT #11

FAQ

What is Cloud-Based Broadcasting?

Cloud broadcasting uses cloud computing to broadcast TV content. In other words, all the TV content is stored in virtual servers. A cloud MSO (multi-site orchestrator) downloads the media files and distributes them to a CDN (content delivery network).  

However, the process is relatively new, likely time-consuming, and expensive. Some TV networks have archived some of their content to the cloud for easy access and broadcasting later but transmitting live sports or similar real-time content is a challenge with cloud-based broadcasting.

Cloud-Based Broadcasting

Also, data-heavy production workflows transitioning to the cloud chew up vast amounts of storage, networking, and processing resources.

Understandably, most TV networks are holding on to what they are more familiar with and what has worked all these years. But cloud-based broadcasting is not a passing cloud (no pun intended).

Several companies have partially moved their resources to the cloud—Netflix is one of them. Netflix’s personalized content repository is an amalgamation of different storage solutions, which includes the cloud.

Production houses upload their movies and shows to the cloud. Netflix encodes the cloud-stored content to its format and distributes it across its network.

Even traditional networks, such as the BBC, have shifted some of their workloads from traditional data centers to the cloud. BBC is very keen and started moving things to the cloud in 2012.

AWS Summit Online ASEAN 2021 | Channel production and broadcast in the Cloud - What's possible now?

Conclusion

With the advent of cable and satellite TV and later OTT TV technologies, traditional TV broadcast has lost some of its sheen. However, it’s still relevant and not going anywhere anytime soon.

Standard broadcast TV has been around for decades and the broadcast technologies that came after it have only built on what was already proven and available.  

Although OTT has become a significant force and talks of networks moving to the cloud can be heard in the distance, the underpinning technology would still be the original broadcasting method.

If you’re curious about OTT and cloud-related broadcasting, it’s imperative to learn the fundamentals. This article intended to do just that—cover the basics.


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