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.