Two television broadcasters are set to initiate modest trials of a new over-the-air on-demand digital television system.

Fisher Communications and Hubbard Broadcasting announced what they are calling a soft consumer launch of a mobile digital television service, called MyDTV, in Seattle and Minneapolis, respectively. Both are initially distributing 750 receivers in each of their respective markets.

The broadcast system was defined by the Mobile500 Alliance, a set of 50 broadcasters looking to use their TV spectrum for over-the-air broadband TV service.

Announced last year, the system relies on antenna dongles that viewers can connect to their iPads or iPhones. They then download an app, register for the service (an authentication step), and can then use their devices as mobile TVs, with many of the same features and functions associated with cellular wireless multi-screen services.

A key difference that the Mobile500 Alliance is banking on for its potential success is that access to over-the-air signals is free, while the meter is always running on LTE-based broadband TV.

Another contrast is that broadcasters have the most efficient multicast video standard extant – far more efficient than unicast broadcasting on LTE. Mobile500 even makes the argument that the service will be a boon for wireless carriers, in that it will draw video traffic off LTE networks, which are being severely taxed by growing demand for video.

Elgato manufactures the receiver accessories and the MyDTV app; Expway provides the MyDTV middleware and captures audience measurement; Accelerated Media delivers interstitial and banner advertising; Neustar Media provides secure and reliable infrastructure; and Broadcast Interactive Media provides program listing data. The Mobile500 Alliance also said it is working with both Nielsen and Rentrak to evaluate the launch data.

The service is being called MyDTV. The MyDTV app supports closed captioning and includes an electronic program guide, built in social media and an optional live record feature.

Accelerated Media helped line up Lincoln Motor and Chrysler/Jeep to advertise during the launch. They will run both banner ads and ads displayed during channel changes.