There’s an old fable about a dog lying in a manger. The dog can’t eat the hay in the manger, but it blocks the horse from eating. The moral: People frequently begrudge something to others that they themselves cannot enjoy.

So we turn our attention to Dyle, the latest flavor of mobile digital TV. As a service, it’s a dog. It uses TV station bandwidth to send a signal that only Dyle-approved devices can receive, and requires each device to be registered online to work. It’s using free bandwidth, but it only promises to remain free to viewers (which it ominously calls “subscribers”) through the end of 2012.

The problem Dyle purportedly solves is viewing live digital TV while moving, as in a car or train. Based on the FAQs, it might not work inside buildings, so I’m guessing that subways are out. It won’t work in airplane mode, so that leaves flyers out. You wouldn’t watch it while driving. So that leaves passengers on buses, cars, and trains, if they can pick up a signal inside one of those things.

Other reports such as this old Washington Post story suggest another reason for Dyle’s existence: To justify retaining bandwidth instead of letting the FCC hand it to cell phone companies to improve internet access. Or if broadcasters ever have to sell it, to improve that real estate so it isn’t a vacant lot. By creating a competitor to IP-based mobile video, broadcasters have built an plausible alternative to handing over that bandwidth.

Any new service is going to have a chicken-egg problem, but Dyle has few chickens or eggs. Despite some proof-of-concept standalone devices, mobile TV needs to be on the smartphone that’s already in the viewer’s pocket. But it was only last month that Dyle was finally able to announce the first Dyle-compatible phone, which uses MetroPCS service. (I don’t think the major cell companies are going to rush to embrace the technology that will help the FCC deny them bandwidth.) And stations? Dyle has exactly one in Colorado. And that’s one more than in at least 10 other states. In Washington DC, where you’d think they’d be showing it off to FCC staffers, Dyle has five stations. A cornucopia of entertainment it ain’t.

I have zero knowledge of Dyle’s internal decision-making, and I’ve been wrong before, but I see Dyle as a service that takes away free publicly licensed TV bandwidth that could have been used for more digital sub-channels such as MeTV and Antenna, and then spoons it out to the few “subscribers” who might actually use it. I don’t mind setting aside a little room for broadcast mobile TV, but Dyle is a dog.