Broadcom announced a chipset that converts digital video to analog; the chips are being used in inexpensive set-top boxes (STBs) that are being deployed by Comcast.

STBs based on the Broadcom chipset are being produced by Motorola, Thomson and Pace. Last month, Thomson announced that it was providing DTAs to Comcast (story here). Pace Micro Technology also has a deal in place with Comcast for the adapters, while Motorola is reportedly providing them to the nation’s largest cable operator, as well.

MSOs have several strategies available for managing bandwidth limitations, including deploying switched digital video (SDV), expanding bandwidth to 1 GHz and reclaiming analog spectrum, among others. Comcast intends reclamation of analog video and the use of STBs built around the new Broadcom silicon. 

Comcast can give its analog subscribers one of the new boxes, which measure only about 4 inches by 5 inches, and continue to provide 70 to 80 analog channels of standard-definition (SD) video. Comcast can then choose, on a system-by-system basis, to reclaim its entire digital spectrum right away, or reclaim some portion of its analog spectrum now and the rest later, explained John Gleiter, Broadcom’s senior director of marketing for cable products.

Gleiter said he expects that STBs based on the Broadcom chips could be made that will cost less than $50, perhaps less than $40.

The DTAs are a cheaper alternative to digital set-top boxes, but while they convert the digital signals back to analog at the TVs, they don’t provide other digital cable features such as video-on-demand (VOD).

Cable operators are looking at going all-digital to reclaim bandwidth in order to offer more high-definition (HD) channels or wideband deployments, but the DTAs also help them provide signals to analog sets after the broadcast digital transition goes into effect on Feb. 17 of next year.

Cable operators can reclaim between 250 MHz and 300 MHz in each system that goes all digital. If a typical cable system has 79 analog channels and the operator decides to move 59 of those channels to digital, while perhaps leaving 20 or so as a life-line analog service for some select markets, it would reclaim 354 MHz. Given 354 MHz of reclaimed spectrum – and the fact that on average, 10 standard-definition (SD) MPEG-2 digital programs can be inserted into one 6MHz slot – this yields enough bandwidth for nearly 590 channels.

The BCM3545 DTA chip is designed in a 65 nanometer process, which means it’s smaller and draws less power. The new DTA chip is based upon the earlier generation BCM3543 system-on-a-chip (SoC) that is used in many terrestrial broadcast designs and is Energy Star-compliant.

The 3545 is now in production. Pricing is available upon request. The chip can be used in conjunction with the company’s silicon tuner; the combination provides a complete RF-in, RF-out chipset, Gleiter told CED.

More Broadband Direct:

• Broadcom A-D video chip powers set-tops for Comcast

• Migration to IPv6 moving slowly

• Qwest reaches tentative agreements with 2 unions

• 2008 Cable Hall of Fame Honorary Committee members announced

• Widevine's DRM solution selected by CinemaNow

• Pew: TV news audience stable, online news audience increasing

• Broadband Briefs for 8/18/08