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CAS - Set top Box Analog Vs. Digital  |
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Four years ago, cable operators in US and Europe decided to change their CAS from analog to digital. Mainly, this was an attempt to preserve their business from the DTH threat. Pirates stealing the signals were also an issue with the industry. History now tells us this move to digital was a mistake.
Several European cable operators migrated to Digital CAS in the last few years. Digital CAS promised security, multiple channel line up and additional services from which the operator could derive extra revenues. Companies such as NTL and Telewest in the UK, Kirsch in Germany, UCN in Europe and Adelphia in the USA invested large sums in the new technology, buying new head-ends, new set top boxes but they underestimated the size of the task required to upgrade their networks to take the digital signals. All these companies are now in Chapter 11, due partially to the costs of running a digital network.
Digital CAS promised additional revenues from the added services such as internet access, PPV among other features. However this has failed to emerge as a significant source of revenue as bulk of the subscribers opt for basic CAS. Also, each additional feature such as PPV requires additional investments at the head-end and in the infrastructure.
Digital Security
It is important to note that the security techniques are the same in all systems whether analog or digital. The video signal is scrambled and a control data stream is simultaneously transmitted to authorise the set top box. It is not true that all analogue systems are less secure than digital systems. Analogue encryption systems have been in the market for many years and range from the older and less secure sync manipulation versions through to state of the art video processing offering excellent security. Being Digital does not ensure better security. The encryption algorithms of leading CAS companies are available easily - some are even posted on the Internet!
Traditional analog systems have suffered in recent years from piracy of signals and the stigma of being associated with old technology. However, today's facts paint a different picture. Analog systems based on sync manipulation and inversion techniques are indeed relatively easy to defeat. It is to these types of system that people refer when they claim that analog CAS cannot be secure.
The more recent and advanced systems use digital technology, within the box, to produce a highly secure yet cost effective solution. Using techniques such as Line Cut and Rotate; line shuffle or a combination of both; produces video which is extremely obscure and practically impossible to reconstruct without massive computing power and access to extreme electronics. Indeed, a situation exactly the same as a traditional digital system. The Aqtual technique introduces elements of randomness in the encoding, which cannot be decoded without the use of very expensive technology.
The Aqtual CAS has been designed to incorporate the best from the digital and analog worlds. It uses advanced, state-of-the-art digital circuitry in an open-design to manipulate the video into a highly encrypted signal. This signal is completely obscure and extremely secure. The encryption technique utilizes complex "random number-based" algorithms to ensure that it cannot be ever broken.
Analog systems are in vogue even as of date in a large number of western nations. For instance the DALVI CAS has been implemented in over 25 countries worldwide and has not had a single case of piracy in any country. Among program providers, HBO and Turner use such systems.
Analog Features
Contrary to popular belief, Analogue systems too can provide additional services and features such as:
- OSD / messages or even individual messages
- Pre-paid token based applications
- Fingerprinting
- PPV or near PPV
- Internet access and other similar features can also be provided where applicable. These are normally achieved through either a telephone or cable modem for the return path
- They can work in either one way or two-way environments ensuring that most features that can be offered through a digital system can also be achieved through analog systems.
Ease Of Deployment
Digital set top boxes are not tolerant of input power, slope and reflections on the network. All of these problems will cause picture "blocking" resulting in subscriber dissatisfaction. Solutions to these problems are usually expensive, take a lot of time and require complex on-the-ground engineering.
Analog systems have the benefit of being extremely tolerant of cable system imperfections, which is essential to the Indian. They can accept a wide range of input powers, at least 5 or 6 times larger than a digital unit; they are tolerant to large adjacent channel slopes and they are resilient to reflections on the network. The time and cost to implement an analogue solution is several fold less than that for a digital solution.
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