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The series of cutpoints is determined by a pseudo-random sequence. Channels were decoded using a pseudorandom number generator (PRNG) sequence stored on a smart card (aka Viewing Card). To decode a channel the decoder would read the smart card to check if the card is authorised for the specific channel. If not, a message would appear on screen.
The most common of these was a channel-based filter that would effectively stop the channel being received by those who had not subscribed. These filters would be added or removed according to the subscription. As the number of television channels on these cable networks grew, the filter-based approach became increasingly impractical.
African Cable Television - commenced operations on 1 December 2014; operations were discontinued a few months later; CTL; Daarsat; DStv [4] [5] - Other networks like HiTV (out of operations) and StarTimes have increased the competitiveness of the cable TV market.
Some analogue decoders were addressable so that cable companies could turn channels on or off remotely, but this only gave the cable companies control of their own descramblers — valuable if needed to deactivate a stolen cable company decoder but useless against hardware designed by signal pirates.
The relatively strong K u band transmissions allowed the use of dishes as small as 90 cm for the first time. [8] On 4 March 1996, EchoStar introduced Digital Sky Highway (Dish Network). [9] This was the first widely used direct-broadcast satellite television system and allowed dishes as small as 20 inches (51 cm) to be used.
DVB-T, short for Digital Video Broadcasting – Terrestrial, is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 [1] and first broadcast in Singapore in February 1998.
However, now "virtual channel" (technically known as logical channel number) numbers are common. So, Channel 4 digital signals may now actually be broadcast on channel 43, or any other frequency. When the ATSC tuner does a channel scan, it finds the signal on channel 43, learns that this material is called "Channel 4", and remembers that mapping.
QAM is a modulation format and does not specify the format of the digital data being carried. However, when used in the context of US digital cable television, the format of the data transmitted using this modulation is based on ITU-T J.83 Annex B ("J.83b").