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- Subject: r.v.s.tvro FAQ - Part 4/10
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- PART FOUR - Compression, Encryption and Encoding Methods
-
- * What Television Broadcast Standards are compatible with BUDs?
-
- All television distribution uses some set of technological standards
- incorporated to allow specific types of reception. This is mainly important in
- terms of the type of TV set you use and what part of the world you are in.
- Satellite television, generally speaking, is compatible with all standards of
- television broadcasting; the only necessary information needed is whether or not
- a particular model/type of receiver will work with your television set and what
- country a satellite transmission is intended to be viewed in.
-
- (This FAQ is not meant to be a comprehensive technical guide to how television
- itself works. It is only meant to distinguish between different technological
- standards so that they can be recognized and differentiated as simply as
- possible.)
-
- 1. NTSC - NTSC, which stands for National Television System Committee, was
- established in 1941 as the original standard for television broadcasting. It
- primarily exists in North America and Japan. In the simplest terms, NTSC has a
- 525-line screen image delivered at 60 half-frames per second. Your television
- (if you live in North America or Japan) is probably an NTSC compliant
- television.
-
- 2. PAL and SECAM - These are standards that are not used in North America. PAL,
- or Phase Alternating Line, is the standard for television in most of Europe and,
- for that matter, is the most used television standard in the world. Unlike NTSC,
- PAL has 625-line screen image delivery delivered at 50 half-frames per second.
- The primary difference between NTSC and PAL is that the phase of the color
- components is reversed from line to line and the color difference signals are of
- a different type. SECAM is a third standard used in France, Russia, and a few
- other places in the world. Both PAL and SECAM are considered to have superior
- horizontal resolution than NTSC.
-
- NTSC, PAL, and SECAM refer to general low-definition television viewing
- standards and do not address the issue of compression of broadcast bandwidth.
-
- * What Compression Schemes are used with BUDs?
-
- Digital compression allows for more than one video and/or audio channel per
- satellite transponder.
-
- 1. DigiCipher II - DigiCipher II (DC2) is a digital encoding and encryption
- format developed by General Instruments (now part of Motorola) that is used for
- many American digital TVRO transmissions. In order to view DC2 channels, a
- special receiver called 4DTV is required. DC2 is a proprietary standard based
- upon MPEG-2. DC2 technology can be licensed to other companies, but no other
- companies have requested a license. Only Motorola manufactures 4DTV receivers.
- Those made for consumer BUD use cost around $400-$800 suggested retail, but are
- typically available at discounts that at times can be quite deep.
-
- 2. DVB/MPEG-2 - MPEG-2 is a general encoding scheme used for many differing
- digital technologies; DVB, which stands for Digital Video Broadcasting, is the
- satellite television-specific variety of the MPEG-2 standard. This is not so
- much a competing digital standard as it is an OPEN standard. This standard is
- used in most of the world outside of the U.S. for digital TVRO broadcasts. Many
- international and non-traditional programming is found using DVB/MPEG-2. Many
- U.S. DVB feeds are free to air and are receivable with a DVB/MPEG-2 FTA digital
- satellite receiver. Channels using this standard may or may not choose to stay
- free-to-air indefinitely; once a network disappears, it may or may not be gone
- forever to consumer TVRO viewers.
-
- For more complete information about DVB/MPEG-2, see the MPEG-2/DVB (Satellite)
- FAQ written by the Delphi DVB Hobbyists. It is located at:
-
- http://dvbwave.com/faq
-
- And Rod Hewitt's "North American MPEG-2 Information" at:
-
- http://www.coolstf.com/mpeg/index.html
-
- * What Encryption Methods are used with BUDs?
-
- The type of encryption depends on whether the transmission is analog or digital.
- In North America, there are still encrypted analog channels, although more and
- more channels are switching to digital compression and the encryption methods
- used with digital channels.
-
- The only important remaining analog encryption method is VideoCipher II+
- Renewable Security, or VC-II RS for short. VC-II RS was developed by General
- Instruments. The original VideoCipher I was developed in the mid-1980's by
- M/A-Com (who was later bought out by GI) when satellite encryption was just
- beginning. VideoCipher I was short-lived and was replaced by VideoCipher II, and
- later VideoCipher II+. VC-II RS is the last version of this encryption scheme
- that will probably ever be developed as more and more channels use digital
- encryption methods. All modern IRDs have VC-II RS decoding capability.
-
- Besides VC-II RS, the other common form of analog encryption still used is
- Leitch. This is used primarily by networks such as ABC and ESPN. The other
- notable types of analog encryption are Oak Orion and BMAC. Oak Orion was a
- standard used by Canadian satellite transmissions until most Canadian
- subscription channels moved to Bell ExpressVu (DBS) and StarChoice (DigiCipher
- II). Oak Orion is no longer used. BMAC was a third analog encryption scheme but
- is no longer used much anymore.
-
- More importantly these days are digital encryption methods. Here is a
- description of these methods:
-
- 1. DigiCipher II - DigiCipher II (DC2) is the defacto American standard for
- digital TVRO encryption. The only hybrid digital/analog IRD is Motorola/GI's
- 4DTV receiver. With the introduction of the Motorola/GI 4DTV sidecar receiver in
- 2001, you no longer need to replace your older analog IRD to enable DC2
- reception. There are no third-party DC2 receivers, unlike analog TVRO IRD's. No
- third-party companies have requested a license, so Motorola/GI never has
- licensed the technology. Canadian StarChoice is transmitted in DC2, and
- StarChoice receivers are manufactured by Motorola/GI.
-
- (The following are DVB/MPEG-2 encryption methods.)
-
- 2. PowerVu - used by AFRTS, NBA TV, RDS - Roseau des Sports, Musique Plus,
- MusiMax, Le Canal Nouvelles TVA; others
-
- This is a standard developed by Scientific Atlanta. You need either the
- Scientific Atlanta PowerVu 9223 receiver, which runs about $1600, or
- the Scientific Atlanta PowerVu 9234 receiver, which runs about $750.
- The 9223 is designed for cable companies to allow them to receive
- MPEG-2 signals that are uplinked for their benefit. Consequently, its
- user interface is very complex and is not designed for channel surfing.
- The 9234 "Business Satellite Receiver" is a little more user friendly.
-
- 3. Irdeto - used by ABS-CBN International, Lakbay TV, Channel D; others
-
- This is a standard developed by Irdeto Access.
-
- 4. Nagravision - used by Caliber Learning Network, other private networks
-
- This is a standard developed by Kudelski.
-
- 5. Viaccess - used by some programming on Telstar 5 satellite
-
- This is a standard developed by France Telecom.
-
- 6. Wegener - used by Empire Sports Network, Televisa, XEW - Canal 2, XHGC -
- Canal 5; XEQ - Canal 9; others
-
- This is a standard developed by Wegener Communications.
-
- Note: There is no consumer receiver that can receive both DigiCipher II/VC-II RS
- *and* DVB/MPEG-2 programming and there probably won't be one available anytime
- soon. General Instruments produces a commercial grade receiver (DSR-4800) that
- will receive both Digicipher II and DVB/MPEG-2.
-
- A WORD ABOUT 4:2:2 SCREEN PIXEL RATIO
-
- Most DVB/MPEG-2 receivers receive what is called 4:2:0 screen ratio for picture
- resolution. But certain DVB/MPEG-2 channels, usually network and/or studio
- feeds, use what is called 4:2:2 screen ratio. This involves the ratio of video
- data to vertical pixel and horizontal pixel color. 4:2:2 is NOT part of the
- standard DVB specifications but is used mainly by studios that need better
- picture quality than standard DVB offers. This is the standard currently used
- for in-the-clear reception of NBC, as well as Warner Brothers and Fox network
- feeds. Most consumer FTA receivers cannot receive signals with the 4:2:2 ratio;
- a more expensive receiver is required. Note that 4:2:2 is NOT a type of
- encryption; however, like certain types of encryption, it does force the TVRO
- viewer to make certain considerations when purchasing receiving equipment.
-
-
-
-