As expected, Motorola and Cisco Systems have filed waiver requests with the Federal Communications Commission in regard to obtaining exemptions for their low-cost digital terminal adapters (DTAs).

Earlier this month, the FCC granted a three-year waiver request for Evolution Broadband’s DMS-1002 and DMS-1002 CA boxes with DTAs, which have a price range of $44-$50 per box (story here) . Evolution’s waiver request was the first of its kind at the time, since it was an equipment vendor rather than a cable operator seeking exemption from the integrated set-top box decree by the FCC that went into effect in July of 2007.

The waiver allows Evolution to sell its boxes without the more expensive CableCards that were required by the separable security mandate.

In the FCC’s Evolution ruling, it said it would look favorably on other DTA vendors, which include Cisco, Motorola, Thomson and Pace, getting waivers in order to meet the “low-cost, limited-capability” standard set forth in the FCC’s 2005 Deferral Order.

On Wednesday, the FCC’s Media Bureau issued requests for public comment on Motorola and Cisco’s exemption requests. The public comment period lasts until June 26.

Cisco is seeking waivers for its DTA 30, DTA 50 and DTA 70, while Motorola filed for waivers on its DTA-100 and DTA-100u.

Cable operators are able to reclaim bandwidth by using the DTAs, and Comcast in particular has been using them as it converts analog channels to digital (story here).

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 in the example above – and the fact that, on average, 10 standard-definition MPEG-2 digital programs can be inserted into one 6 MHz slot – this yields enough bandwidth for nearly 590 channels.