Cable Set-Top Box Reference Designs for High-Definition Video Recording Applications - Conexant

Conexant Systems announced two complete cable set-top box (STB) reference designs for high-definition  personal video recording (PVR) applications. The new products are based on the Conexant’s CX2445X DOCSIS 2.0+ and EuroDOCSIS 2.0+ cable modem integrated circuits. The reference designs also support major operating systems including Linux.

The integrated solutions includes core software and drivers that enable developers to quickly develop middleware and innovative applications with either Conexant's CX24500 single-channel or CX2427X dual-channel high-definition MPEG-2/H.264/VC-1 video decoder.

The new reference designs supports for OpenCable applications platform (OCAP ), a middleware software layer specification in North America. In addition, an embedded processor enables advanced hardware security features, and supports major industry security standards including downloadable conditional access system (DCAS ) and multi-stream CableCARD  (M-Card ).

Lewis Brewster, Conexant, said:

In today’s fast-moving marketplace, time-to-market often determines a product’s success, particularly in rapidly growing applications such as personal video recording…

Our new reference designs provide manufacturers with the ability to shorten product development cycles, which can provide them with a competitive edge that may translate to greater market share down the road…

The CX2445X family of DOCSIS 2.0+ front-end cable cable set-top box  chips feature three demodulators with downstream channel bonding capability, which increases bandwidth capacity. This product also includes integrated cable PHY layer and supports 55-1&55-2. SCTE standards. (SCTE = Society of Cable Telecommunications Engineers).

The reference designs comes in two options:

• With CX24500 single-channel video decoder for mass market cable set-top box devices with personal video recording capabilities.
• With CX2427X dual-channel device which is capable of decoding two HDTV programs simultaneously for picture-in-picture display, and supporting networked personal video recording. 

Both of the decoders support key video compression standards including MPEG-2, MPEG-4 advanced video coding, H.264, and VC-1.

The CX2427X and CX24500 are based on a ARM 1176 processor. CX2427X and CX24500  include DDR2 memory interface, a graphics rendering engine, an integrated L2 cache and  also a Jazelle  Java hardware accelerator.

The video decoders features:

• Multiple video outputs including high-definition multimedia interface (HDMI) 1.3 with high-bandwidth digital content protection (HDCP) 1.2
• Two Ethernet MACs with a media independent interface (MII).
• A Broadcast Television Systems Committee (BTSC) stereo encoder and channel 3/4 RF modulator
• Three USB ports
• Audio DACs

Those features enables future expansion for networking technologies such as HomePlug  A/V, MoCA, or 802.11 wireless networking.

About CX2445x DOCSIS 2.0+ Cable Modem IC

CX2445x is an integrated cable front end chip for next-gen cable set-top boxes, digital cable TV network interface units and DOCSIS cable modems. The chip combines three in-band digital cable channel receivers supporting a combination of two digital video channels with a DOCSIS set-top gateway (DSG) or up to three bonded channels for DOCSIS 2.0+ services.

The product family of CX2445x includes:

• CX24452
• CX24454
• CX24455
• CX24457

CX2445x cable modem IC also has a legacy out-of-band data communications channel receiver and a cable channel transmitter supporting either DOCSIS 2.0+ or legacy OOB signaling. It also offers multiple MPEG-2 transport stream interfaces.

Connectivity of CX2445x cable modem IC are provided via USB2.0, PCI bus and MII.

Features CX2445x DOCSIS 2.0+ Cable Modem chip includes:

• Three in-band downstream QAM channels
• ARM940 main system CPU
• OOB downstream channel compliant to SCTE 55-1 and 55-2
• DOCSIS2.0/DOCSIS1.x/EuroDOCSIS/DVB/Opencable compliant
• PCI host bus interface
• USB 2.0 MAC and PHY
• Embedded IEEE 802.3 MAC with MII
• High density, 23mm BGA package
• Down stream channel bonding
• IPv6

About DOCSIS (Data Over Cable Service Interface Specification)

Data Over Cable Service Interface Specification (DOCSIS) defines the communications and operation support interface requirements for a data over cable system. It permits the addition of high-speed data transfer to an existing Cable TV (CATV) system. It is employed by many cable television operators to provide Internet access over their existing hybrid fibre coaxial Hybrid fibre-coaxial (HFC) infrastructure.

DOCSIS is developed by CableLabs and contributing companies that include: ARRIS, BigBand Networks, Broadcom, Cisco, Conexant, Correlant, Intel, Motorola, Netgear, Terayon, and Texas Instruments. DOCSIS. The first DOCSIS specification was version 1.0, issued in March of 1997, with revision 1.1 following in April of 1999. Because of increased demand for symmetric, real-time services such as IP telephony, DOCSIS was again revised to enhance upstream transmission speeds and Quality of Service (QoS) capabilities; this revision - DOCSIS 2.0 - was released in December 2001. Most recently, the specification was revised to significantly increase transmissions speeds (this time both upstream and downstream) and introduce support for Internet Protocol version 6 (IPv6). This
version, DOCSIS 3.0, was released in August 2006.

As frequency allocation band plans differ between US and European CATV systems, DOCSIS standards have been modified for use in Europe. These changes were published under the name of EuroDOCSIS. The main differences account for differing TV channel bandwidths; European cable channels conform to PAL TV standards and are 8 MHz wide, whereas in North-America cable channels conform to NTSC standards which specify 6 MHz. The wider bandwidth in EuroDOCSIS architectures permits more bandwidth to be allocated to the downstream data path (taken from a user’s point of view, "downstream" is used to download data, while "upstream" is used to upload data). EuroDOCSIS certification testing is executed by Excentis (formerly known as tComLabs), while DOCSIS certification testing is executed
by CableLabs. Typically, CPE gear receives "Certification", while CMTS equipment receives "Qualification".

Source:

• Conexant’s Cable Set-Top Box Reference Designs
• DOCSIS - Data Over Cable Service Interface Specification) - Wikipedia.org