Mobile TV

Readers had much to say regarding an Oct. 25 article about mobile TV, “Mobile DTV: A technology in search of a business model.”

Dear editor:

$130,000 to ensure that viewers keep watching? Sounds like a cost of doing business! If a klystron went out, you'd replace it and not sweat the business model.
Doug Ferguson

Dear editor:

Broadcasters: Stop [messing] around and just have this be a successful free-to-air service. Nobody is going to pay for premium service. Dumb in-car systems won't have the ability to enter any subscription IDs.
Joseph Fiore

Dear editor:

The business model is to have your salespeople go out to the world and sell it. Include it in a current buy if you have to, but sell it. Present the case for why people will accept advertising with the service and collect the check.

If everyone is so enamored with it, then build the subscriber base necessary and then sell against it. Unless you can't. Only a dunce thinks it's the technology or that people will love it for free. Maybe the salespeople are too stuck in their ways to switch hats and think like an advertiser. If you owned your own company and you wanted to sell your product, would you spend money on mobile television?

Video routers Q&A

Broadcast Engineering's Sept. 21 webcast “Video routers” generated a slew of questions from attendees. Here are some selected questions and answers from the presenter, John Luff. To view the on-demand version of the webcast, visit

Q: What are the routing considerations to handle 3-D in the studio? Is this a bandwidth issue or dual paths?

A: Excellent question! At this time stereoscopic 3-D production is done primarily in two formats. The most easy to understand, and the closest to the origination, is discrete left- and right-eye signals, most commonly both 1920 × 1080i30/50 on SMPTE 292 infrastructure. This requires routing two signals with a single selection, which can be done with a macro or salvo command. In the future, 3G-SDI (1080p60) signals will become common.

The other format often used is to time domain multiplex the two signals on one HD signal, with side-by-side or over-under combinations. This allows a single wire to carry both channels, and it fits perfectly in any SMPTE 292-capable router. Obviously, this reduces the resolution when sent to the home, but it works in common infrastructure.

Q: Why do most router control interfaces still use RS-232/485 and not Ethernet?

A: A high percentage of new routing systems use IP connections for all control. There remain many legacy products that use other communications methods, but I would expect that they will disappear in coming years.

Q: What is the direction of the industry in dealing with consumer digital transmission formats such as HDMI and the new VESA standard, DisplayPort? What about digital rights management?

A: The output from routing will eventually have to accommodate many of the interfaces you mention. Today, specialized hardware interfaces convert SDI (HD or SD) signals to display input standards. However, in the sense that multiviewers are routers or extensions of routing, they often have HDMI or other display outputs natively.

Q: Could you discuss the tie line configuration to get more inputs /outputs with two smaller routers?

A: Using small routers connected with tie lines, managed in software, often works and can reduce cost, but it needs to be well-planned. For instance, in the extreme, a pair of 10 × 10 routers connected by five tie lines in both directions uses 50 percent of the capacity for the tie lines, but will not “block,” i.e. all signals can be available to all outputs. But the net effect is that of a single 10 × 10 router. The key is to decide if nonblocking is a requirement or whether the resources can be managed on a probable-use basis like public switched telephone networks, where on average everyone can make calls because not everyone will make a call at the same time.