CableCARD™ Overview

Cable operators provide CableCARDs to subscribers. The cards provide secure access to encrypted digital cable programming. This separation of the host receiver from the conditional access function enables portability of retail host devices among cable networks throughout the country. For example, if a consumer purchases a set-top box or an integrated digital TV (DTV) in New York and then relocates to Los Angeles, that set-top box or integrated DTV will be operational on the new regional cable network.

CableCARD 1.0
The early cable removable security cards were called Point-of-Deployment (POD) modules. CableLabs later coined the term CableCARD™ and began describing the removable security devices as CableCARD security modules. The SCTE standards (ANSI/SCTE-28 and ANSI/SCTE-41) still use the term POD module. These are two names for the same thing.

From the very early specifications and draft standards, the CableCARD module has been a two-way device. That is, it included the functionality to enable two-way communication on the cable plant. This two-way communication is necessary for a variety of advanced cable services including video on demand (VOD), switched digital video (SDV), interactive services and applications.

The media has frequently reported that first-generation CableCARD 1.0 modules are one-way devices1. This is simply not true. CableLabs had always intended to develop the CableCARD module and host receiver standards with two-way capability. However the manufacturers of digital TVs requested that a host standard be developed that only had one-way capability. This one-way cable-ready receiver was defined by the FCC's Plug & Play order and by the Joint Test Suite (JTS). It is the definition of this one-way receiver that lacks the ability for two-way functionality, not the CableCARD module. While the FCC defined the elements of the one-way cable-ready receiver, CableLabs continued to define specifications for two-way receivers.

When a CableCARD 1.0 module is used with a two-way receiver (e.g., Samsung HLR5067C) that card supports all the necessary two-way functionality for VOD, SDV, and other interactive services.

Multistream CableCARDs

Over the years, technology advanced and CableLabs updated the CableCARD module specifications to create Multistream CableCARDs. Multiple stream processing is required in, for example, PVRs that record and play at the same time, picture-in-picture (PIP), and picture-on-picture PoP) type applications.

The development of the replacement interface specification was originally called the Multistream CableCARD Interface Specification. It updated the security system to support triple-DES (3DES) or FIPS PUB 46-3, added support for up to 6 simultaneous transport streams, and made use of the serialized interface, similar to USB-2.0, to achieve lower host receiver costs and higher data transfer rates. While doing this, the card maintained the original PCMCIA physical interface for backward compatibility.

Before anyone actually implemented this new Multistream CableCARD Interface Specification, it was recognized that it repeated a large portion of the requirements in the original CableCARD 1.0 interface specification. Having two separate specifications with duplicate requirements meant a tough job keeping everything lined up as specification clarifications came in from implementing teams. To resolve this, CableLabs began the process of merging the original (single-stream) CableCARD 1.0 interface specification with the new Multistream card interface specification. This combined specification includes all requirements for both previous specifications and is known as the CableCARD Interface Specification 2.0 or CCIF-2.0. A companion document that combined the requirements of the copy-protection specifications also was developed and is known as the CableCARD Copy Protection Specification 2.0 or CCCP-2.0. It is anticipated that most cable operators will simply migrate to the Multistream CableCARDs for all CableCARD uses. Multistream CableCARDs will work, in a backwards compatible manner, in Hosts that were originally built to the single stream CableCARD standard.

CableCARD 2.0

These new CableCARD-2.0 specifications were issued on March 31, 2005; at the same time the former CCIF 1.0 and Multistream Card (M-Card™) specifications were closed. Along with this update, changes were made to all related OpenCable specifications to require use of the new CCIF-2.0 and CCCP-2.0 in all places that previously referenced the former specifications. Beginning June 6, 2005, all CableLabs certifications of OpenCable products have been tied to CableCARD-2.0 (or CCIF-2.0) specifications. As of that date, new Cards and new Hosts have been certified to support the CCIF-2.0 and CCCP-2.0 specifications.

CableCARD Terminology

Since CableCARD-2.0 Interface specifications now included all the requirements from both the original (single-stream) CableCARD interface and the new (multi-stream) CableCARD interface, terminology was developed to distinguish between the two different operating modes and product types:

• S-CARD: A two-way CableCARD module that follows the original CableCARD 1.0 Interface specification or implements only the single-stream portion of the CableCARD-2.0 Interface specification.
• M-Card: A two-way CableCARD module that implements all of the multi-stream functionality as well as the single-stream functionality (for backward compatibility purposes) of the CableCARD-2.0 Interface specification.
• S-Mode: The operating mode of the interface when the original parallel transfer function is being used in single-stream mode, which limits the video transfer rate to 40 Mbps in each direction.
• M-Mode: The operating mode of the interface when the new serial transfer function is being used, regardless of how many transport streams are actually being delivered, to provide up to 200 Mbps data transfer rate for the video stream in each direction.
• S-Host: An OpenCable Host Device or UDCP that operates exclusively in the S-Mode, regardless of how many tuners are included.
• M-Host: An OpenCable Host Device or UDCP that has implemented the M-Mode variation of the interface, regardless of how many tuners the device includes.

Migration to Multistream Support

There are four types of devices that can be authorized to use the CableCARD module interface. This electronic authorization comes in the form of digital certificates that are embedded within the Host receiving device that accepts a CableCARD module. In order to receive these digital certificates a manufacturer must sign a license and build a product according to certain requirements.

The first type of Host product that can make use of the CableCARD module is the Unidirectional Digital Cable Product (UDCP) or "Digital Cable-Ready Receiver." These products were defined by FCC rules. The license a manufacturer signs for such products is the DFAST license and the requirements are found in the Joint Test Suite Conformance Checklist: PICS Proforma. For more information, please see www.cablelabs.com.

A second type of Host product is an M-UDCP device or a unidirectional receiver that uses an M-Card operating in M-Mode. In other words, a product that supports multiple tuners with a single CableCARD.

The third type of Host product that can use the CableCARD module is the OpenCable Unidirectional Receiver (OCUR). The OCUR employs DRM technology (e.g., WMDRM and Real Helix), and is used to provide premium digital cable content to certain PCs. The PC itself must meet certain criteria established by the DRM provider, but is not certified separately by CableLabs. OCUR products are defined by CableLabs OpenCable specifications. The product must follow the requirements defined by the CableLabs OCUR specifications and DRI specifications. Presently these devices are required to support the S-Mode interface, but work is underway to extend their support to allow the M-Mode interface.

The fourth type of Host product that can make use of the CableCARD module is an OpenCable Host Device. This device is licensed by CableLabs and the requirements for this product are found in the Host-CFR-2.0 specification. The main difference between this product and that which is defined by the FCC is the support for two-way functionality. The OpenCable Host Device specifications include all of the requirements necessary to support two-way cable services (e.g. video-on-demand or switched digital video), while UDCP devices do not. It is important to note that it is the receiver implementation that determines support for two-way services, not the functionality of the CableCARD module. All CableCARD modules are two-way capable.

The two-way OpenCable Host products originally were required to support the S-Mode interface and were exclusively an S-Host. The first two-way OpenCable products certified followed these requirements. Later requirements were changed for OpenCable devices mandating the M-Mode interface as a baseline.

Compatibility and Backward Compatibility of CableCARD Modules and Host Devices
Care was taken in the development of the multistream interface specification to ensure full backward compatibility. This is achieved by specific requirements on both the Host side and the Card side of the interface.

First it was established that the CableCARD module takes responsibility for operating in both modes, depending on the capabilities of the Host. This means that every M-Card is required to be able to operate equally in both the S-Mode and in the M-Mode and to be capable of sensing the capabilities of the Host.

When an M-Card is inserted into an S-Host, the CableCARD module will sense that the Host is designed for the S-Mode and will follow the S-Mode protocol. From the Host perspective, the CableCARD module will look and function like any other S-Card.

If that same M-Card is inserted into an M-Host, the CableCARD module senses that the Host is designed for the M-Mode and follows the M-Mode protocols, using the latest 3DES security and enabling the faster transport speeds capable of supporting multiple tuners.

This backward compatibility provision of the CableCARD module permits cable operators to migrate smoothly to an exclusive inventory of M-Cards that will be used for all products, with no further need to purchase or inventory older S-Cards.

Placing the backward compatibility burdens on the CableCARD modules assists Host manufacturers by freeing them from any obligation to include redundant or unnecessary circuitry while allowing them to take full advantage of the lower cost hardware design of the M-Mode interface.

Two-Way Functionality of CableCARDs and Host Devices
The ability to support two-way and interactive cable services such as VOD and SDV is a responsibility shared between the CableCARD module and the Host. There are circuits and functionalities needed on both sides of the CableCARD module interface to complete the connection and to enable full two-way signaling.

First, it is important to understand how two-way cable communication works at a high level. The two-way communications are broken down into the downstream and upstream directions. The downstream communication path describes the messages that flow from the cable headend to the subscriber device and the upstream communications are those that flow from the subscriber device back (up) to the headend. From the cable headend perspective, downstream = talking, while upstream = listening. From the subscriber equipment perspective, downstream is for listening and upstream is for talking.

All UDPC devices, M-UDCP devices, OpenCable Host devices and CableCARD modules support downstream channels, but only CableCARD modules and OpenCable Host devices support upstream channels.

There are three distinct languages (or protocols) that are used on cable systems for the two-way communications: (1) Aloha (the protocol, defined by the ANSI/SCTE 55-1 standard, used by Motorola systems); (2) DAVIC (the protocol, defined by the ANSI/SCTE 55-2 standard, used by Scientific Atlanta systems); and (3) DSG (the protocol, defined by the ANSI/SCTE-106 DOCSIS Set-top Gateway standard, used by a variety of cable systems). All three protocols transmit their upstream signals on channels in the 5 MHz to 42 MHz frequency band. In order for a Host to support two-way services on any cable system, it must be capable of transmitting upstream signals using any of the three protocols. Only products compliant with the OpenCable Host specifications include the transmitters capable of supporting all three upstream protocols. Products built to the Plug & Play or Digital Cable Ready (DCR) FCC requirements are unidirectional only, and do not include these transmitters and are unable to support two-way services.

On the other hand, CableCARD modules always were designed to support two-way functionality, including the original CableCARD 1.0 interface specifications. The CableCARD module includes the knowledge of the upstream transmission standards and protocols used by each cable operator and is able to format and prepare messages for that protocol. Those upstream messages are sent to the Host device for transmission (when so equipped). The upstream transmitter also is under the complete control of the CableCARD module to set frequency and output power. CableCARD modules are equipped to recognize the presence of these upstream transmitters in an OpenCable Host device and to use them as necessary. They also are able to detect the absence of this transmitter in a unidirectional Host and to operate in a one-way mode.

1 For example: (1) From Wikipedia, the free encyclopedia; (2) “A CableCard That Hasn't Been Able to Kill the Set-Top Box,” Eric A. Taub, The New York Times, 2006-07-03; (3) CableCARD: A Primer, Nate Anderson , ars technica 2006-02-06; (4) FAQ: CableCard? What's that?, Richard Shim and Jim Hu, CNET (2005-01-05).