The Conditional Access is a digital signal technology which is mainly used to decrypt the transmitted digital signals for the digital TV users. A CAM or a Conditional Access module is an electronic device with a slot for accommodating a smart card which enables a set-top box or Integrated Digital Television with the appropriate hardware facilities to receive and process the conditional access contents that has been encrypted by a Conditional Access system. Usually, a CA module is used with the DBS (Direct Broadcasting Services) and pay channel services. For the DVB broadcasting, the PC TV card is used as the Common Interface Form of CAM. Usually, these devices consists of a smart-card slot for premium content viewing and provide controlled access to the authorized subscribers to digital TV broadcasting services by encrypting the transmitted programming signals. Since a CA module is a removable device, you can replace it with another one if it gets broken or damaged.
Usually, a CA module uses two different types of DVB protocols called MultiCrypt and SimulCrypt. The SimulCrypt enables the authorization of TV programs for display and the MultiCrypt helps the subscribers to use multiple CAMs within a set-top box by using a TV PC card. Most of the Conditional Access modules are compatible with the MPEG2 as well as MPEG4 receivers. Usually, a Conditional Access provider provides the software as well as hardware equipment to the Digital Signal Broadcasters (DSB) and the DSB then integrates the Conditional Access system into their equipment. Nowadays, you can see plenty of encryption systems that support the Conditional Access modules. Some of them are Nagravisio, Logiways, Mediaguard, Viaccess, KeyFly, Irdeto and Verimatrix.
Types of CAM
Nowadays, you can avail of two different types of Conditional Access modules from the market – common CAMs and professional CAMs. The common CA module is considered the basic form of CAM and these devices consist of only a single channel. For watching the encrypted transmissions, the common CAM devices are enough and most of the digital TV broadcasting services provide such CAMs to their subscribers. A professional Conditional Access module is a multichannel system and usually, these devices consist of two, four or eight channels. As the name indicates, these devices are intended for professional use and are mainly used in DVB test industries.
Steps in a Conditional Access process
The Conditional Access process starts with the reception of the signals by the signal receiver. The information received is transmitted to the CA module, which contains the unscrambling algorithms of the content provider. The CA module verifies the existence as well as validity of the smart card which contains the authorization code of the subscriber. The CAM unscrambles the data and returns the data into the signal receiver if the authorization code is accepted. Otherwise, the signals remain scrambled and the device will restrict the access. Once the code is accepted, the receiver decodes the signals and then transmits them to the output section for viewing the channels. The picture and sound clarity is exceptionally good.