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Today’s Show:

Mobile DTV

According to the Open Mobile Video Coalition, Mobile Digital Television, or Mobile DTV, will be available in 71 million homes in the US in the next 12 months.  That equates to roughly two-thirds of all US households by this time next year.  With that almost instant market penetration, we’re bound to see some shifts in HDTV, home theater and certainly consumer electronics.

What is Mobile DTV?

According to the Open Mobile Video Coalition website: www.openmobilevideo.com:
“The current network of broadcast transmission towers that carry TV signals to your home can be retrofitted to also deliver a Mobile DTV signal. That signal has the ability to deliver local, full-motion digital broadcasts on multiple mobile devices, without the need for additional broadcast spectrum.”

“With little cost, broadcasters can install a Mobile DTV exciter and signal encoding equipment on existing TV transmission systems and gain the ability to transmit a robust, digital mobile TV signal. Consumers will receive that signal on various Mobile DTV devices.”

So far, so good.  For a relatively low investment, our current local broadcasters will be able to transmit live TV to portable devices like cell phones, portable media players, portable DVD players, computers and tablets. You’ll be able to watch live TV on the train, in the doctor’s office or while sitting outside the fitting room without the need for a good data connection or a device like a slingbox.

The video is intended for mobile devices, so it won’t eliminate the need to run coax cable to your home theater. Initially you’ll get small format video encoded with H.264 base profile. Eventually they plan to scale the video quality up to 480p and hopefully (although we haven’t seen this written) include 5.1 audio as well. So while it won’t be good enough for your home theater, it could be acceptable for getting TV in your garage or shed or other secondary area.

And for watching TV on the go, for those of us who like to keep the kids nice and quiet and entertained in the back of the car? They’ve tested reception and have shown clear, consistent reception in vehicles traveling at over 100 miles per hour. But if you’re driving that fast with kiddies in the car, do us all a favor and slow it down. Train rides, however, go ahead an go as fast as you want, Mobile DTV can keep up just fine.

What’s the catch?

We all know that there’s not such thing as a free lunch; there has got to be a catch.  And there is.  Mobile DTV is basically another multicast channel on the same frequency band the broadcasters have already been allocated. To support mobile TV, the broadcaster will have to steal bandwidth from your HDTV program.  If done right, it’s possible we won’t even notice. But if they continue to support the same multicast sub-channels they already have, and simply carve off more bandwidth for Mobile, we all suffer.

The Open Mobile Video Coalition website shows a couple of hypothetical scenarios for how this could be done. With ATSC, each broadcaster has 19.4 Mb/s of DTV spectrum. About 1.4 Mb/s of this is typically taken up by what they call data or ancillary services, leaving 18 Mb/s for video.  For some broadcasters, like CBS, you get all 18 Mb/s for high def. With other broadcasters you get less, maybe 10 or 12 Mb/s for high def and the remaining 6 to 8 Mb/s supports other standard def channels available for your viewing pleasure.

The hypothetical scenarios show that 4 to 6 Mb/s of bandwidth is enough to support 2 to 4 Mobile DTV channels. Carving out a huge amount of bandwidth, like 10 to 12 Mb/s would allow a broadcaster to send out as many as a dozen different Mobile DTV channels. Think of how many different commercials you could sell on that many channels! But doing the math, it looks like you can support 1 Mobile DTV channel on less than 2 Mb/s, allowing a broadcaster to provide very high quality HTDV and still provide a simulcast of the main feed for Mobile devices.

What about devices?

LG has a portable DVD player with built-in Mobile DTV support available at Amazon.com and the HT Guys store for a list price of $250, but at the time of this article, you can actually buy it for as little as $77! (buy now)  The LG DP570MH has a 7” screen with 480×234 resolution you can use to watch DVDs or local DTV broadcasts.  Amazon also has several USB tuners in the $70-$80 price range.

Beyond what’s currently on the market, many manufactures have announced devices in an attempt to ride the 71 million household wave.  RCA for example, will be bringing out several portable TVs and a portable car tuner for your minivan’s rear entertainment system.  You can find out more about RCA’s upcoming products at www.RCAPortableTV.com.

If the prediction of 71 million homes by April 2012 comes true, Ara’s prediction that Automobile Based Mobile Video will become a reality in 2011 looks like it has really good odds.  But instead of requiring a cell phone or mifi connected to a computer or slingbox at home gobbling up all your data via 3G or 4G or 5G, all you’ll need is a simple $75 portable TV or DVD player. No monthly contract required.

Download Episode #474


Posted by The HT Guys, April 14, 2011 9:22 PM

About The HT Guys

The HT Guys, Ara Derderian and Braden Russell, are Engineers who formerly worked for the Advanced Digital Systems Group (ADSG) of Sony Pictures Entertainment. ADSG was the R&D unit of the sound department producing products for movie theaters and movie studios.

Two of the products they worked on include the DCP-1000 and DADR-5000. The DCP is a digital cinema processor used in movie theaters around the world. The DADR-5000 is a disk-based audio dubber used on Hollywood sound stages.

ADSG was awarded a Technical Academy Award by the Academy of Motion Picture Arts and Sciences in 2000 for the development of the DADR-5000. Ara holds three patents for his development work in Digital Cinema and Digital Audio Recording.

Every week they put together a podcast about High Definition TV and Home Theater. Each episode brings news from the A/V world, helpful product reviews and insights and help in demystifying and simplifying HDTV and home theater.