DigiCipher 2, or simply DCII, is a proprietary standard format of digital signal transmission and it doubles as an encryption standard with MPEG-2/MPEG-4 signal video compression used on many

communications satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Ear ...

television Television, sometimes shortened to TV, is a telecommunication Media (communication), medium for transmitting moving images and sound. The term can refer to a television set, or the medium of Transmission (telecommunications), television tra ...

and audio signals. The DCII standard was originally developed in 1997 by General Instrument, which then became the Home and Network Mobility division of

Motorola Motorola, Inc. () was an American multinational telecommunications company based in Schaumburg, Illinois, United States. After having lost $4.3 billion from 2007 to 2009, the company split into two independent public companies, Motorola ...

, then bought by

Google Google LLC () is an American Multinational corporation, multinational technology company focusing on Search Engine, search engine technology, online advertising, cloud computing, software, computer software, quantum computing, e-commerce, ar ...

in Aug 2011, and lastly became the Home portion of the division to

Arris In architecture, an arris is the sharp edge formed by the intersection of two surfaces, such as the corner of a masonry unit; the edge of a timber in timber framing; the junction between two planes of plaster or any intersection of divergent a ...

. The original attempt for a North American digital signal encryption and compression standard was DigiCipher 1, which was used most notably in the now-defunct PrimeStar medium-power

direct broadcast satellite Satellite television is a service that delivers television programming to viewers by relaying it from a communications satellite orbiting the Earth directly to the viewer's location. The signals are received via an outdoor parabolic antenna commo ...

(DBS) system during the early 1990s. The DCII standard predates wide acceptance of DVB-based digital terrestrial television compression (although not cable or satellite DVB) and therefore is incompatible with the DVB standard. Approximately 70% of newer first-generation

digital cable Digital cable is the distribution of cable television using digital data and video compression. The technology was first developed by General Instrument. By 2000, most cable companies offered digital features, eventually replacing their previo ...

networks in North America use the

4DTV 4DTV is a proprietary broadcasting standard and technology for digital cable broadcasting and C-band/Ku-band satellite dishes from Motorola, using General Instrument's DigiCipher II for encryption. It can tune in both analog VideoCipher 2 and dig ...

/DigiCipher 2 format. The use of DCII is most prevalent in North American digital

cable television Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with bro ...

set-top boxes. DCII is also used on Motorola's 4DTV digital satellite television tuner and Shaw Direct's DBS receiver. The DigiCipher 2 encryption standard was reverse engineered in 2016.

Technical specifications

DigiCipher II uses QPSK and BPSK at the same time. The primary difference between DigiCipher 2 and DVB lies in how each standard handles SI metadata, or System Information, where DVB reserves packet identifiers from 16 to 31 for metadata, DigiCipher reserves only packet identifier 8187 for its master guide table which acts as a ''look-up table'' for all other metadata tables. DigiCipher 2 also extends the MPEG ''program number'' that is assigned for each service in a transport stream with the concept of a

virtual channel In most telecommunications organizations, a virtual channel is a method of remapping the ''program number'' as used in H.222 Program Association Tables and Program Mapping Tables to a channel number that can be entered via digits on a receiver' ...

number, whereas the DVB system never defined this type of remapping preferring to use a registry of ''network'' identifiers to further differentiate ''program numbers'' from those used in other transport streams. There are also private non-standard additions to DVB that add virtual channel remapping using ''logical channel numbers''. Also unlike DVB, all text used in descriptors can be compressed using standard Huffman coding which saves on broadcast bandwidth and loading times. DigiCipher II uses Dolby Digital AC-3 audio for all channels, although MPEG-1 Level 2 audio is not supported.

External links

Technical page on digital satellite signalsHistorical Perspective: HBO Implements Scrambling

References

{{broadcast encryption Cryptographic protocols Digital television Television terminology Conditional-access television broadcasting Digital rights management systems 1997 introductions Telecommunications-related introductions in 1997 Audiovisual introductions in 1997