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Discussion Starter #1
The 8VSB (ATSC) standard for OTA DTV was never meant to involve mobile reception. Antennas must be statically mounted and aimed for optimum signal. Likewise the international DVB-T OTA DTV standard is being augmented with a new mobile DVB-H standard for the same reason.

With the increasing popularity of mobile video players, Samsung and Rohde & Schwarz have co-developed a new standard for moble OTA DTV called A-VSB. No word on any official recognition of it by standards bodies, but given that it is an open standard its likely that other vendors and broadcast entities will join in.
RIDGEFIELD PARK, N.J., BUSINESS WIRE -- Samsung Electronics and Rohde & Schwarz announced that their co-developed Advanced-VSB (A-VSB) Mobile DTV system has won TV Technology magazine's STAR Award (Superior Technology Award Recipient) at the 2007 National Association of Broadcasters (NAB) convention. A-VSB is a proposed open standard, ready to roll out in time for the February 2009 transition to all-digital TV broadcasting, that broadcasters can implement at low cost, providing an all-new distribution channel to reach consumers with live TV on the go via portable media devices, whether traveling by car, bus, train, or walking down the street.
http://www.broadcastnewsroom.com/articles/viewarticle.jsp?id=137972
 

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Hey stampeder,

Do you think this will be utilizing vertical polarization like DVB-T? Will my car be sporting a 7' whip antenna? :eek:

And maybe you can tell us,... Could a broadcaster theoretically simultaneously transmit a vertical and horizontal signal on the same frequency without interference? Would they would be out of phase by 90 degrees?
 

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Competitor to A-VSB: MPH from Harris and LG Electronics

A-VSB apparently has some competition:
NAB2007 offers two competing ATSC in-band modulation schemes

RF broadcasters at NAB2007 saw two competing ATSC in-band modulation schemes for sending video to mobile devices using the digital TV spectrum.
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The two ATSC-compatible systems — A-VSB from Samsung and Rohde & Schwarz, and MPH from Harris and LG Electronics — could allow local stations to get in the mobile TV game without having to rely on outside service providers or telcos to get the signal to subscribers. The systems also provide another potential revenue stream for stations' local content.

The competing, noncompatible technologies were demonstrated in Las Vegas on two respective vans equipped with receiving equipment, a spectrum analyzer and LCD monitors to view the signals. Each van showed DTV signals coming from local Sinclair Broadcast Group stations, with the overall 19.4Mb/s signal being split up into a main channel at 15Mb/s and two sub channels. (In the case of the MPH demo, one stream was sent at about 560kbps, using 2.2Mb/s, called 1/2 rate, and another 2.2Mb/s at about 300kbps, or 1/4 rate.) This was to demonstrate how a station might replicate its traditional DTV channel for larger mobile devices, like a laptop or an in-car video system, and send out a smaller signal for display on a cell phone or handheld player, with its 2in x 3in screen, or to stream pure data.

During live demonstrations, both systems worked well. The demos also illustrated how the main DTV channel break ups and freezes when the van was moving (even when moving very slowly at say a traffic light).
From: http://broadcastengineering.com/RF/nab2007-atsc-modulation-schemes-0423/?cid=img0507071

Interesting that the signal used was from a Sinlcair station. The Sinclair group tried years ago to get the 8VSB modulation replaced with COFDM; the type of modulation Europe and Japan use for their DVB-T and ISDB-T digital broadcasting respectfully (they don't use ATSC).
 

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Discussion Starter #4
99gecko said:
Could a broadcaster theoretically simultaneously transmit a vertical and horizontal signal on the same frequency without interference? Would they would be out of phase by 90 degrees?
Actually that is pretty much what QAM is - signals at right angles. Could this be done OTA? Sure, but that would mean hauling out a lot of existing ATSC infrastructure that hasn't even been paid for yet, so my take is that they'd have to make such an A-VSB system so appealing (i.e. advertising $$$) and easy to implement that broadcasters would be willing to add it to their repertoire.
 

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Discussion Starter #5
On first reading of these press releases my concern is about a further cutting of the bandwidth pie. HD quality would suffer if a chunk of bandwidth has to be devoted to special mobile TV programming. Hopefully they can keep it to a minimum if use becomes widespread.

Regarding the MPH system touted by Harris and LG, those are 2 very heavy hitters in the tv broadcasting industry so keep an eye on both standards. We may see either one win the day (or both? shudder)...
 

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stampeder said:
We may see either one win the day (or both? shudder)...
... or neither. As you said, I doubt if stations will be eager to replace their existing ATSC infrastructure any time soon unless they can re-use the vast majority of the infrastructure and replace only a small subset of it or there is a strong financial incentive. One way this could happen is if every new cell phone gets this technology, that would open up a huge market. Morning and late afternoon television would become much more popular if people could watch it for free when taking the bus or train (or car? shudder ;)) to and from work. This would be most appealing in cities with heavy transit use. In other cities it might create incentive for more people to use transit. This probably won't happen as the oil/auto industry will most likely buy the technology and kill it. ;)
 

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I wonder if either A-VSB or MPH have a feature that transmits the channels of neighboring network affiliates so that when you get out of range of one station, it will automatically tune into the neighboring network affiliate. If done well and they are both showing the same program, you might notice a blip, but otherwise the transition will be seamless to the viewer (better than a blank screen and having to hunt for an affiliate). It probably wouldn't be used by a commuter, but would be good for back seat TVs on long road trips (good for PBS Kids).

It isn't commonly used, but this feature is available on RDS for analog radio.
 

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ATSC mobile update

from ATSC.org:
“The ATSC-M/H Standard will facilitate broadcasters’ use of their DTV broadcast channels to provide new services directly to small hand-held receivers, laptop computers and vehicles moving at a high rate of speed,” said ATSC President Mark Richer. “ATSC-M/H will be backwards compatible, allowing operation of existing ATSC services in the same RF channel without an adverse impact on existing receiving equipment.” Broadcasters will be able to allocate a portion of their 19.39 Mbps/8-VSB signal to mobile and handheld while continuing to transmit services such as HDTV.

“Development of a standard for mobile and handheld services is a major priority of the ATSC’s strategic plan,” said Glenn Reitmeier, Chair of the ATSC Board of Directors and VP, Technology Standards, Policy & Strategy, NBC. “We encourage participation in our standards development process and welcome technical proposals for consideration by our Technology and Standards Group (TSG)."
and also from ATSC.org:
ATSC Issues Request for Proposals for Mobile and Handheld Specifications

WASHINGTON, May 21, 2007 –The Advanced Television Systems Committee (ATSC) Technology and Standards Group (TSG) has issued a Request for Proposals (RFP) to identify potential specifications to be used for its mobile and handheld standard (ATSC-M/H). The ATSC-M/H Standard will enable delivery of television content and data to mobile and handheld devices via broadcast DTV signals. Services based on ATSC-M/H will not preclude or prevent operation of current ATSC services or have any adverse impact on legacy receiving equipment. ATSC-M/H will support a variety of services including:

* Free (advertiser supported) television content and other services delivered in real-time
* Mobile and handheld subscription-based TV
* Non-real-time content download, to playback later
* Datacasting
* Interactive television
* Real-time navigation data for in-vehicle use

The RFP is available at www.atsc.org. Preliminary responses including an overview of the proposal are due on June 21, 2007. Detailed descriptions of the proposal are due on July 6, 2007. As always, whether a proposed methodology is incorporated into an ATSC Standard is determined in accordance with the due process procedures of the ATSC. In reaching its conclusions, the ATSC may combine various aspects of multiple proposals into a final specification.
 

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Discussion Starter #9
Broadcast Industry Group Demands Single Standard, No Mobile DTV Format War

Glad to see that key broadcast industry players don't want anything to do with a Mobile DTV "Format War":
Broadcasters Push Vendors on Mobile DTV

(Broadcasting & Cable)

The Open Mobile Video Coalition, a collection of station groups interested in developing and implementing a mobile TV system that works within the existing digital TV spectrum, has issued an "Open Letter to the Technology Industry" urging vendors to participate in the standardization of mobile DTV technology.

The group, which counts Belo Corp., FOX Television Stations, Gannett Broadcasting, Gray Television, ION Media Networks, the NBC & Telemundo Television Stations, Sinclair Broadcast Group, and Tribune Broadcasting among its members, would like to see a single standard for mobile DTV emerge and avoid the type of time-consuming format war that has plagued other new technologies. Specifically, it is encouraging vendors to participate in the ATSC's formal standards process that was announced in April and launched last month.
http://www.broadcastnewsroom.com/articles/viewarticle.jsp?id=154118

And here is the Open Mobile Video Coalition website:

http://www.openmobilevideo.com/
 

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You would think a mobile format would be good, as with LCD TVs in cars/vans becoming the standard and not the exception, OTA would be a good way to get local content.
 

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Mobile OTA DTV could affect stations plans for repeaters in small communities on major transportation routes. With current realities, it is difficult to justify transitioning many of these repeaters to DTV and they could be shut down in 2011. If the repeater could also be used as part of a mobile broadcast network, it would add to the business case for the transition and could save the repeater. For this to happen, the mobile network would have to be planned before the 2011 analog shutdown, otherwise the broadcast license would be lost.
 

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ATSC receives 10 proposal submissions for mobile, handheld standard

Update from:
Broadcastengineering.com

The following organizations have submitted preliminary proposals:

* Coding Technologies
* Coherent Logix
* DTS
* LG Electronics and Harris
* Mobile DTV Alliance
* Micronas Semiconductor
* Nokia
* Samsung Electronics and Rohde & Schwarz
* Thomson
* QUALCOMM

Detailed descriptions for all submitted proposals are due July 6.

The MPH system from Harris and LG Electronics and the A-VSB system from Samsung Electronics and Rohde & Schwarz were demonstrated at NAB2007. Both share a slice of the 6MHz DTV channel along with a main and multicast SD and/or HD channel.
 

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From:
HDTVexpert.com (click to see the pics !)
edit: a diversity antenna is a multiple antenna system where the receiver selects the strongest signal from amongst the different antenna - similar to MIMO (routers etc)
....LG and Harris claim both modes will provide steady reception at speeds as high as 200 mph.
....
Both systems worked very well for mobile DTV reception. If anything, the MPH system has the edge in that it doesn’t need the diversity antenna system, which means MPH receivers can be a lot smaller and more portable. While the A-VSB demo worked well, the prototype Samsung receiver and antennas are too large to carry in your pocket.

It’s important to remember that the video delivered to these systems is very low resolution and not HDTV. The QVGA resolution makes it possible to use low bit rates so that either system can piggyback into an existing 8VSB broadcast. 160x120 pixels may not sound like much, but they’re more than adequate for handheld viewing of video and basic graphics.

Both A-VSB and MPH also look more attractive as secondary revenue streams for broadcasters, most of which aren’t deriving any extra bucks at present from their second, third, and fourth minor channels. These channels often feature weather, local news, and syndicated services like The Tube’s music videos.

In contrast, mobile DTV could turn out to be a multi-million dollar business with relatively low implementation costs for each local broadcaster. The mobile VSB streams aren’t detected by conventional set-top boxes or integrated DTV sets and have little if any impact on 8VSB coding and electronic program guide data.
and from: twice.com
HOW A-VSB WOULD WORK

A-VSB incorporates one mandatory and two optional technologies that work like this:

Broadcasters transmit a supplementary reference sequence (SRS), or reference, signal. Current-generation HDTVs would ignore the signal, but an SRS-equipped receiver would look for the signal and lock onto it continuously. “Because it [the tuner] knows what it should receive, it compares what it sees to what it knows it should receive,” said Godfrey. The tuner then compensates for the difference.
....
Another optional A-VSB technology is called “single-frequency network,” a delay signal that broadcasters could insert into their transmission to synchronize the simultaneous transmission of a program on their assigned channel from multiple towers in a market. By filling in coverage gaps, the technology would further improve mobile and portable reception but also improve reception by legacy DTV sets in homes where over-air line-of-sight signals might otherwise be blocked, Godfrey said. Synchronization is needed because the reception of two signals slightly apart in time would confuse the tuner and cause the screen to go black, he said.
And this is the part that a lot of OTA'ers will object to:
If they adopt SRS, broadcasters who transmit a single HDTV program would encounter no tradeoff in the resolution of a signal sent to legacy and future DTV sets, Godfrey contended. At its highest setting, he explained, the SRS signal would use only 2-3Mbps of the 19.4Mbps of bandwidth allocated to DTV stations, “and most HDTV broadcasters are not using the full 19.4Mbps for the main HD program,” he contended. “MPEG-2 encoders used by broadcasters are so good now that even for rapidly changing images in sports broadcasts, 17Mbps is fine for a completely high-definition picture without tradeoffs,” he contended.

A few stations might run into tradeoffs, however, if they broadcast one HD signal and two to three multicast standard-definition (SD) signals simultaneously.

The Turbo Coding option, which uses up much less bandwidth than SRS, is scalable up to 600kbps, which could suffice for improved reception on handheld devices with screens up to 5 inches, he added. For in-car TVs with 7-inch to 10-inch screens, a bit less than 4Mbps of bandwidth could be enough, he said.

If an HD station pushes Turbo Coding to 4Mbps for “big-screen” mobile applications, and sets aside the maximum 3Mbps for the SRS signal, only 12.4Mbps would be available for the station’s main HD program. At that data rate, “It’s still HD but a bit of a challenge,” Godfrey admitted
 

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The QVGA resolution makes it possible to use low bit rates so that either system can piggyback into an existing 8VSB broadcast. 160x120 pixels may not sound like much, but they’re more than adequate for handheld viewing of video and basic graphics.
That must be a typo. QVGA is 320x240. QQVGA is 160x120. Basic graphics I'd say!
 

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Kenwood to develop in-car MPH receiver based on inband mobile DTV system

From Broadcastengineering . com
Dec 21, 2007 8:14 AM

Kenwood has become the first major manufacturer of automotive electronics to announce its intention to develop a mobile DTV receiver for over-the-air broadcasts in North America.

Preliminary plans for a prototype in-car MPH receiver will be announced publicly at the 2008 International CES in January at the Kenwood booth N1001.

In late 2008 or early 2009, the company will manufacture prototype terrestrial DTV receivers based on the MPH in-band mobile DTV system, developed by Harris and LG Electronics. Other CE companies may follow suit shortly thereafter.
 

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Discussion Starter #16
South & Central America Split On Digital OTA TV Standards

The 400 million potential Digital Mobile OTA TV watchers in South and Central America might soon find that TV stations in adjoining countries don't necessarily broadcast in ways that they can watch. Up for grabs are national standards for traditional and mobile DTV broadcasting.

This is an important issue for travelers who will have future mobile phones and other portable devices for watching OTA DTV.

Brazil is heavily pushing the Japanese ISDB-T standard, Uruguay has opted for the European DVB-T standard, while Mexico has chosen the ATSC standard used in the rest of North America.. Peru, Chile, and Argentina are still deciding, while other countries have not publicized any moves towards DTV.

A British company has created a multi-standard chipset, but ATSC seems to be missing from it:

http://www.theinquirer.net/gb/inquirer/news/2008/02/29/multi-standard-tuners-kill-fud
 

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The article stampeder mentioned is about "mobile TV standards", and since the mobile version of ATSC has yet to be standardized, perhaps that's why there is no chipset that supports ATSC yet?

TVl
 

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Discussion Starter #18
Good point about a Mobile ATSC standard not having been chosen yet - given that multi-standard chipsets are being designed I wonder if anyone is working on a set that will cover the different Mobile ATSC schemes...
 

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Handheld ATSC Television - not yet

Has anyone come across one of these yet? With the upcoming NTSC (analog) switch off, I have yet to personally see one and I would think there would be a market for portable TVs that could do ATSC in the palm of your hand.
 

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Discussion Starter #20
Yep its being done, but the problem is that the ATSC and DVB-T digital TV standards were designed only for stationary receiving antennas. If you move the receiving antenna you will almost certainly lose the digital lock for at least a moment. If you put your antenna up on a treetop and its a windy day, you'll have trouble making and/or keeping a digital lock due to all your antenna's motion.

DVB is being expanded into the DVB-H format for handheld devices (fed through mobile phone system to phones, Blackberrys, etc.) and the DVB-M format for mobile receivers (boats, cars, rvs, min-TVs, etc.)

ATSC is going mobile in one of 2 competing formats, A-VSB and MPH:

http://www.digitalhome.ca/forum/showthread.php?t=63639
 
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