The cable industry is proposing a method for two-way switched digital video (SDV) services to run on inherently one-way, digital, cable-ready devices that use CableCARD security modules.

    Buried within an 80-page filing with the Federal Communications Commission (FCC) , the NCTA has proposed the use of a small adapter, dubbed a "Tuning Resolver," to receive programs that are switched, rather than broadcast, to the subscriber.

    That issue bubbled to the surface earlier this year, when TiVo Inc. (Nasdaq: TIVO - message board) complained that its CableCARD-capable, but one-way, digital video recorders (DVRs), would not be permitted access to channels that an operator offered using SDV technology. (See Cable, TiVo Pondering SDV Problem.)

    SDV is a growingly popular technique that conserves cable bandwidth by streaming linear channels only when a customer in a given service group selects them. MSOs such as Time Warner Cable Inc. (NYSE: TWC - message board), Cablevision Systems Corp. (NYSE: CVC - message board), Cox Communications Inc. , and Comcast Corp. (Nasdaq: CMCSA, CMCSK) have either begun to deploy SDV or are just starting trials. (See SDV Deployment Snapshot.)

    In the filing, the NCTA said the external Tuner Resolver adapter would provide two-way SDV channels to one-way digital cable products, including set-tops and digital TVs, via a firmware modification and a USB 2.0 connection. It added that "many" unidirectional digital cable products (UDCPs), including TiVo-made DVRs, have one or more USB 2.0 connectors, and suggested they also might be upgradeable for SDV through only a firmware upgrade.

    The NCTA hinted at such a solution in a filing made to the FCC on June 5, 2007, noting that engineers from cable and TiVo were working on a solution, but offered no technical detail.