Mary Robinson is all about real-world information on the switch to digital television signals. The success of the DTV switch will depend on regular folks understanding new technology and getting it running in their homes. Ms. Robinson is weighing in on those nitty-gritty details, sharing her enthusiasm for TV-signal technology with those who are less technically inclined. She’s developed an expertise through years of hands-on experimentation, pulling in signals from the rooftop of her Texas home. Now she’s a resource for consumers struggling with the digital switch. We discovered Mary right here on TVWeek.com, where she reliably dispensed information in the comments section of this story, First Digital TV Converter Box Wins Government Approval about the digital switch. Let’s keep the conversation rolling!



Digital Transition Answers

FCC Rule Allowing DTS Should Help Consumers

March 2, 2009 10:23 AM

I ran across something on the FCC Web site this weekend that knocked my socks off. The commission has adopted rules to allow what is known as a Distributed Transmission System, or DTS for short.

DTS allows a full-power, Class A or low-power digital television station to build and operate smaller transmitter sites, all on the same channel as the main transmitter, to help cover underserved communities due to terrain, tall building multi-path and reduced coverage area because of differences in the analog and digital signal coverage contours.

Full-power stations can use DTS as the main system for broadcasting their signals, or they can be used in addition to full-power transmitters and will be covered under one license.

Class A and low-power stations can use DTS the same way, but they would all be covered under different licenses.

It is much more spectrum-efficient than using translators, due to the fact that all transmitters would use the same channel. DTS uses new technology to keep the signals from interfering with each other.

According to the FCC rules, a Table of Distances (TOD) has been established to determine how far a station's signal could be expected to go if transmitted at the highest power authorized on a tower that was at the maximum height allowed above average terrain.

There are three zones for television stations in the U.S. Zone I consists of basically a lower quadrant of Wisconsin, the lower half of Michigan's Lower Peninsula, the lower half of New York, the lower halves of Vermont and New Hampshire and the coastal area of Maine down to the upper half of Virginia, West Virginia, then along the border of Kentucky, with Ohio, Indiana, and Illinois included in Zone I with everything in between.

Zone III includes the state of Florida; the coastal sections of Alabama, Mississippi and Louisiana; and the coastal sections of Texas down to the Mexican border, along with the lower section of Georgia.

Zone II is everybody else.

This comes into play with the TOD. For Zone I stations, the TOD has a maximum distance for channels 2-6 of 67 miles. For channels 7-13, the distance is predicted to be 63 miles. In Zones II and III, channels 2-6 can carry 80 miles and channels 7-13 can go 77 miles. UHF channels 14 -51 all carry 64 miles whether in Zone I, II or III. The reference point for each radius is determined to be the main transmitter site.

As an alternative to the TOD, a station can make a case to the FCC to use the "largest station" provision of the rules, which seeks to equalized the coverage areas of stations serving the same market, and to address disparities between VHF and UHF stations.

By adopting the rules, and authorizing stations to use a network of DTS transmitters in lieu of a single transmitter, the FCC hopes to increase spectrum efficiency and improve consumer service.

There are a number of benefits to the DTS service, including serving viewers who could not be reached by conventional means, including rural and remote areas, and filling in gaps in coverage areas caused by terrain. DTS will provide higher-level and more uniform signals throughout a DTV station's coverage area, especially in fringe areas. It will improve reception of pedestrian and mobile devices and should enhance indoor reception for suburban users.

Stations that have had trouble getting higher towers authorized due to FAA concerns or local zoning ordinances can build out to the maximum potential and co-locate on existing wireless towers.

Spectrum efficiency will be enhanced due to all DTS transmitters using the same channel as the main transmitter, as was mentioned above.

DTS can enhance the transition to digital by delivering more reliable signals to viewers and reducing the costs associated with building a large single-tower facility.

And finally, it came to light during the initial switch to all-digital broadcasting In Wilmington, N.C., that some viewers lost reception of WECT because they found themselves outside of the digital contour when WECT turned off its analog transmitter.

DTS involves some exciting technology, and addresses a lot of the problems that posters on this site have been complaining about.

If you are having trouble receiving a station that you were able to get on analog, I urge you to call, write, complain, cry and make the wheel squeak at the station you are not getting. Let them know you expect them to fulfill their obligation of getting you a signal you can receive.

Stations now have no excuse to not provide reasonable coverage to any community in their market area. This is going to be a good thing.


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Comments (7)

JD in the Quiet Corner:

I mentioned DTS in a post here a while ago, I think in response to an EmmGee TV-apocalypse comment (we still like you, Emm!). It was in an article I saw from early last year that was explaining how these remote transmitters can complement the main in certain spots to preserve a station's analog radius. Thought it was cool that stations and engineers do actually care and that technology is always improving (well, almost always... our electric coffeepot (literally. Grr!) doesn't hold water compared to the old Revereware(TM) stovetop percolator).

IIRC, I *believe* that the article stated that these DTS towers probably would not be capable of transmitting high definition, tho. I remember thinking, 'SD is better than nothing.'


mary... the cat lady:

Hey JD,
Nowhere in my perusings of the FCC rules for DTS did I see anything that suggested HD would not be carried. We had a low power station here locally that was a FOX affiliate, and it certainly was capable of carrying HD. One of our full power stations took the FOX affiliation from them however.
I am most certain that they will be able to carry HD, But I will do some research to be sure and post back here when I can.
I would think that if you are in the metropolitan area, and are under served by the main transmitter, and you end up with a supplemental DTS transmitter and it did not carry HD, viewers would scream bloody murder...


DTS must, by it's technical nature, carry the identical programming as the primary feed. It is meant to be operated "on channel," thus distinguishing it from a translator and making it essentially a vehicle to build single frequency networks.

There has been work going on in New York to design and build a system. I believe reports are available on the NTIA's website.


I meant to add...DTS does not come free. It requires a link from the primary transmitter to the DTS location. The signals have to be carefully time coordinated, and you cannot simply pick up the signal over the air and retransmit like a translator can. So there are definitely costs incurred and it may not be effective to build a large network to serve sparsely populated areas.

mary... the cat lady:

Yes, DTS is intended by the rules to remain "on channel" as the license requires. That is one of the exciting things about it. It is so spectrum efficient. 5 DTS transmitters won't need 5 different channels to accomplish what it needs to do as trasnlators would.
Thanks for the heads up about the New York market. That will be interesting to follow.
Our local CBS affiliate is in the process of determining if a DTS system is the way to go or if digital translators would be more efficient for them to regain torritory that was lost by moving from a VHF-lo channel to a UHF DTV facility.
By the rules, a station cannot "cherry pick" where they are going to install DTS transmitters. If they have two or more, the coverage areas of all the DTS tranmitters have to touch or overlap.
Therein lies the delimma of stations in whether to choose DTS or translators. But if translators are chosen, they are not protected as a DTS transmitter would be.
We shall see how this all plays out in the next few months. But it gives great hope to those who are on the fringe or in a null of a main transmitter.
I am hoping this will address those in the fringe areas where severe weather is a very real threat. I think the FCC has done a good thing here.

mary... the cat lady:

TailorMade, another cost for stations is that multiple towers have to be built or placement space on existing towers has to be leased. Also, with Murphy's law being what it is, you have that many more technical things to deal with that have things go wrong over a much larger area. It would not be impossible to have two transmitters go kaput that were 120 miles from each other.
It is a lot to consider for a station.


I can see La Crosse/Eau Claire being a market where this may be a good thing. WEAU 13 (NBC) is in Eau Claire, WHile La Crosse, WI only has channel 67, a translator of KTTC-10... Rochester, MN. However, this is out of market.The main market station does get interferance around St. Francis Hospital. This also includes the UWM campus, which is slightly south of that point. A DTS on a bluff would assist the southern end of La Crosse to get WEAU 13's signal. Vice-versa for WKBT "NewsChannel 8," for Eau Claire.

As for the apocalypse... TVNewsDay said the same thing. the article "DTV FREE BUT FICKLE." It shows how someone 10 miles away from a tx cannot get thier local DTV signals.

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