Broadcast and cable communication systems

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Broadcast vs Cable network vs Online distributors

This page explores the historical methods of signal distribution and reception systems, particularly within broadcast communication network, and delves into potential simulations of these systems.

  • Terrestrial Broadcasting: A Broadcast Station transmits audio and/or video content to a wide audience using radio waves, known as over-the-air broadcasting. This system includes:
Television: Signals are sent from broadcast stations to be received by antennas. This could be analog or transitioned to digital formats like DTV and ATSC. Examples: Local TV stations, network affiliates like ABC, CBS, NBC.
Radio: Terrestrial radio broadcasting uses radio waves from land-based stations. It uses analog systems: Traditional AM (Amplitude Modulation) or FM (Frequency Modulation). AM varies the strength of the carrier wave, while FM varies the frequency for better quality but requires more bandwidth.
  • Cable TV: Cable TV was a system for delivering television programming through RF signals via coaxial cables. It required;
Infrastructure: Physical cable networks to homes
Equipment: Subscribers needed equipment like set-top boxes (STBs) to decode and display the signals
Subscription: Access to cable TV typically required a subscription, akin to Early online services.
  • Satellite Broadcasting:
Satellite TV: Similar to cable, but uses satellites in orbit to transmit signals, providing a wider range of channels and sometimes exclusive content.
Satellite Radio: Under Digital Audio Radio Service (DARS), it involves digital transmission of audio signals from satellites to receivers on Earth.
  • Internet Protocol television and streaming services:
Signal or content is received over an Internet stream or on a network utilizing the Internet Protocol.

Simulators

Name Platform(s) Years(s) Region(s) Enhancements Active Recommended
MyRetroTVs Web '50s, '60s, '70s, '80s, '90s, '00s United States of America ~ ✓* ✓
swimelodeon Web '90s United States of America ? ? ?
radio.garden Web Live Global ? ? ?
Comparison
MyRetroTVs - 1996 news
MyRetroTVs
This website is for watching captured footage from TV channels or various videos from the eras of the '50s to '00s, eliminates the need for handpicking videos and creating a personal collection, which can be time-consuming and require a significant amount of storage space. This website simply gathers videos from specific sources such as YouTube playlists etc, so we can say that this website offers a simulated experience of watching TV channels from during those specific eras. It also supports some basic #Enhancements. While this is a great way to experience retro television, there's room for even deeper immersion. For example adding surfing channel collections playlists, this could be achieved by integrating with Archive.org's vast collection of VHS TV channel surfing captures. Also integration with EmuVR, perhaps with some kind of support for playlists support for libretro core, could be a great next step too.
swimelodeon
This website is for watching '90s Nicktoons, original Adult Swim, old-school cartoons and anime. placeholder text

Enhancements

Name MyRetroTVs
Post-Processing Filters ✓
AI-powered filter compatible
(Freestyle) 		?
Shader Chain ~*
Inverse tone mapping compatible ?
Quality of life Rewind ?
Fast-Forward/Turbo Speed ?
Savestates ?
Video recording ?
User Profile ✗
Command Line Options ?
Built-in Custom resolution/CRTSwitchRes
For using this on Windows OS you need CRT Emudriver.
Another option is using EDID editor tool such as "Custom Resolution Utility". 		Exclusive to libretro cores and GroovyMAME at the moment.
Also there is a project for achieving software emulators like libretro cores and GroovyMAME send the raw RGB data over a network to a core running on MiSTer, it basically turns the MiSTer into a GPU for the emulator allowing for easy setup and use with CRT TVs/Arcade monitors.
Big Picture Mode ?
Misc Netplay or SyncPlay ?
AI Service
With the help of OCR and other techniques, the AI service can provide a live translation of a video, or text-to-speech capabilities for the visually impaired among other things, either on demand or automatically. 		Exclusive to libretro cores at the moment. So there is no support at the moment.
EmuVR support Exclusive to libretro cores at the moment. So there is no support at the moment.

Broadcast television systems

Broadcast television systems (or terrestrial television systems outside the US and Canada) are the encoding or formatting systems for the transmission and reception of terrestrial television signals.

Analog Television Systems

During the 1st and 2nd generation of video game consoles, RF connection was the only way to connect a video game console to a TV. During the 3rd generation some consoles such as the NES had separate outputs for unmodulated signals and all consoles had the option by the 4th generation. By the 5th generation, composite video became the standard form of connecting a video game console

NTSC
NTSC was the first color television system to be widely adopted, NTSC works by transmitting a high frequency color signal on top of the legacy black and white image, the amplitude of this signal determines the saturation while the phase determines hue, this is a property that many early consoles and home computers took advantage of. Every nation using the NTSC system also used a 59.94hz field rate. Many filters exist to replicate this display on emulators.
PAL
PAL was created in Germany as a response to NTSC's susceptibility to hue fluctuations during poor reception conditions. The difference from NTSC is that the phase is inverted every other line, causing phase errors to cancel out, causing a less objectionable drop in saturation instead. The color signal is also in a higher frequency than NTSC, thanks to the larger channel bandwidth on European channel allocations. PAL was almost always used with a 50hz field rate.
PAL-M
PAL-M was only used in Brazil and should not be confused with PAL-60. PAL-M uses PAL encoding on NTSC channel allocations, as such the frequency of the color signal is lower than that of regular PAL, close but not the same as NTSC. As with NTSC PAL-M used a 59.94hz field rate.
SECAM
SECAM (also written as SÉCAM ) was developed in France for similar reasons as PAL. Unlike NTSC and PAL, which transmits a full color signal each line, SECAM alternates between two axes of the color signal, making a delay line mandatory for decoding (hence the name which translates roughly as Sequential color with memory). Also unlike NTSC and PAL this signal is frequency modulated, which makes it more robust to transmission errors. Aside from France, SECAM was used by the Soviet Union and its satellite states. For this reason SECAM is rarely found on video game consoles, most often opting to use a RGB SCART cable instead (in some cases such as the NES, the RGB signal comes from an internal PAL decoder, hence not being "pure" RGB). Rare exceptions are the French Atari 2600 and Soviet Sega Master System
MUSE
MUSE (Multiple sub-Nyquist Sampling Encoding), also known commercially as Hi-Vision (high definition television) was created in Japan in the eighties where it was used for HDTV transmissions as well as laserdisc. MUSE works in a completely different manner from the above systems and was never used for any video game console, and is only mentioned here as it was still an analog system :)
Samples
Comparison table
System Refresh rate Chroma subcarrier frequency Usage Effect of phase errors
NTSC 59.94 3.58 MHz Most of the Americas, South Korea, Japan, Taiwan Color shifts
PAL 50 4.43 MHz Most of Europe, Australia, New Zealand Desaturation
PAL-60 59.94 4.43 MHz 60Hz modes in PAL regions, never used in broadcasting Desaturation
PAL-M 59.94 3.58 MHz Brazil Desaturation
SECAM 50 France Immune
Analog Hidden Signals
Extended Data Services
XDS is a protocol used in analog television broadcasting to transmit additional information like program name, rating, or network name in the vertical blanking interval (VBI) of a TV signal.
Wide Screen Signaling
WSS involves embedding digital metadata within the analog TV signal to inform the television whether the content is formatted for 4:3 or 16:9 aspect ratios, allowing for appropriate display adjustments.
Vertical interval timecode
VITC is a method to encode timecode data in the vertical blanking interval of video signals, allowing for synchronization and frame-accurate editing in video production. It's especially useful for slow tape speeds on analog formats.
Vertical interval test signals
These signals are used in analog television to check and adjust the quality of the broadcast signal. They are inserted during the vertical blanking interval and include patterns for testing aspects like color, linearity, and synchronization.
Video Encoded Invisible Light
VEIL is a technology for embedding digital data into the luminance of video signals. It's been used for applications like interactive TV, DRM, or controlling toys, where the data is invisible to viewers but readable by devices.
Vertical blanking interval
The vertical blanking interval (VBI) is a portion of the television signal where the electron beam in CRTs is turned off to return to the top of the screen. It's used to transmit data like closed captions, teletext, or VITC without affecting the displayed image.
Programme delivery control
PDC is a system primarily used in Europe for controlling video recorders, allowing them to start and stop recording based on broadcast schedules, using data encoded in the VBI.
Ghost-canceling reference
A GCR signal is used in analog TV to combat ghost images (echoes of the main signal caused by reflections). It's transmitted in the VBI to help receivers adjust for better picture quality.
Electronic programming guides
These are systems that provide viewers with on-screen listings of current and upcoming TV programs, often transmitted in the VBI in analog systems or digitally in modern setups.
Copy Generation Management System – Analog
See Copy protection page.
Captioning
Captioning involves adding text to video broadcasts to display dialogue, sound effects, and other auditory information visually, typically embedded in the VBI for analog TV.
Teletext
Teletext is a system for transmitting text and simple graphics within the vertical blanking interval of a TV signal, offering services like news, weather, and program schedules, accessible through a TV's remote control.
Zxnet's teletext viewer
Emulation
Name Active Recommended
zxnet ✓ ✓
Teletext-capable version of JSBeeb ? ~
PagesFromCeefax ? ~

Digital Television Systems

Transmission of television signals using digital encoding, contrasting with the earlier analog television technology which utilized analog signals. At the time of its development, DTV was considered an innovative leap forward, marking the first significant evolution in television technology since the introduction of color television in the '50s.

The transition from analog to digital broadcasting started around 2000. This shift has led to the adoption of various digital television standards across the globe:

  1. Digital Video Broadcasting (DVB): Utilizes coded orthogonal frequency-division multiplexing (OFDM) modulation and supports hierarchical transmission. It's adopted in Europe, Africa, Asia, and Australia, covering approximately 60 countries.
  2. Advanced Television System Committee (ATSC): Employs eight-level vestigial sideband (8VSB) for terrestrial broadcasting. It has been adopted by nine countries including the United States, Canada, Mexico, South Korea, Bahamas, Jamaica, the Dominican Republic, Haiti, and Suriname.
  3. Integrated Services Digital Broadcasting (ISDB): Designed for both fixed and mobile reception, using OFDM and two-dimensional interleaving. It supports hierarchical transmission of up to three layers with MPEG-2 video and Advanced Audio Coding. Japan and the Philippines use this standard, while ISDB-T International, adapted with H.264/MPEG-4 AVC, has been adopted in most of South America, as well as Botswana and Angola.
  4. Digital Terrestrial Multimedia Broadcast (DTMB): Employs time-domain synchronous (TDS) OFDM technology, where a pseudo-random signal frame serves as both the guard interval (GI) of the OFDM block and the training symbol. This standard is in use in China, including Hong Kong and Macau.
  5. Digital Multimedia Broadcasting (DMB): Developed in South Korea, this technology allows for the transmission of multimedia content like TV, radio, and data to mobile devices such as mobile phones, laptops, and GPS navigation systems.
Digital Hidden Signals
Electronic programming guides
In digital broadcasting, electronic programming guides (EPGs) provide viewers with interactive on-screen listings of TV programs, including detailed descriptions, schedules, and the ability to set reminders or record shows, transmitted within the digital broadcast stream.
DVB Content Protection & Copy Management
see copy protection page.
Captioning
Digital captioning involves embedding text data within the digital TV signal for displaying subtitles or closed captions, offering features like multiple language support, text styling, and positioning, which are more flexible and richer than in analog systems.
Broadcast flag
The broadcast flag is a bit in the digital TV signal metadata intended to control whether the content can be copied or redistributed. When set, it signals devices to restrict copying of the content, though its implementation and acceptance varied by region.
Active Format Description
AFD is metadata within the digital video signal that tells the display device how to handle the aspect ratio of the content, ensuring that the video is displayed correctly on various screen formats without cropping or letterboxing unintentionally.
Teletext
In digital broadcasting, teletext continues to be supported through digital teletext or subtitling services, where text and basic graphics are transmitted as part of the digital multiplex, offering services similar to the analog version but with enhanced capabilities due to the digital nature of the signal.

Radio receiver

Recordings of Broadcast Television

Early TV was broadcast live. Different means were invented for recording a broadcast.

Professional formats
Telerecordings, also known as Kinescopes, were means of recording a television program onto film. In 50hz territories, the film ran at 25fps and was synchronised with the image being drawn on a CRT. The image was slightly defocused to avoid recording a scanline structure, as that would beat against scanline structure of the telecine (a device used for transferring film to video) causing moire. Telerecordings were always in black and white, as the shadow mask used on color CRTs would cause moire when superimposed on the grain structure of color film. However, some telerecordings were made without filtering out the PAL subcarrier, which allowed modern methods to recover the "buried" color signal.
Quadruplex by Ampex was the first commercially successful format for recording video, released in 1956. Because a video signal requires significantly higher bandwidth than audio, and the tape speed needed for achieving such a bandwidth was impractical to achieve with linear recording (such as on an audio tape). The solution was to have a set of four magnetic heads rotating as 2 inch tape passed by them, hence the name Quadruplex, as a result the effective tape speed was over 1500 ips, or 100 times the linear tape speed. Audio was still recorded linearly. As technology progressed, smaller less cumbersome format took its place.
Sony's U-matic, released in 1971, was the first video format to store the tape inside a cassette instead of on a reel that required manual threading. While it never caught on as a home format due to its high price, it became popular for industrial and educational use. It also found significant use in newsgathering.
Home formats
While home video recording remained out of reach for two decades, home audio recording was a different matter. A number of otherwise lost programs exist in audio form due to watchers recording their favorite shows onto audio tapes, often by simply putting a microphone near the TV's speaker. More inventive persons would tape the audio signal electronically from the TV.
Several home video formats came out in the 1970s, however the two most important ones were Sony's Betamax (not to be confused with Betacam, which was a later professional format) and JVC's VHS in 1975 resp. 1976. While Betamax had a headstart, VHS came out victorious.

There are preservation efforts by Radio Preservation Task Force, National Recording Preservation Board and Association of Recorded Sound Collections dedicated to project operates in fulfillment of the “to develop an online inventory of extant American radio archival collections.” Over 2000 radio collections are linked in this database and more to come. Lots of recordings and captures preserved on Archive.org as well, such as: Radio Show and Programs Archive. See Tape/casette ripping guide.

See also

Home media or media content playback focused devices

External links

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