FCC proposes digital channel assignments; one worried station is in Detroit

Adapted from Current, Aug. 19, 1996

By Steve Behrens

The digital TV channel numbers proposed by the FCC last week are expected to cover an average of 99 percent of the viewing area that broadcasters' present stations cover, according to the commission's calculations.

Indeed, the "replication" figures for most public TV stations in the top 20 markets checked by Current were 99 or 100 percent, but the match was not nearly so good for WTVS, Detroit: 87.6 percent.

"We're concerned that our station seems to have taken a greater hit in coverage area than any other station in the state of Michigan," says Phil Hejtmanek, WTVS v.p. of engineering. The FCC estimated that the DTV channel will reach 268,000 fewer people than the present analog signal. Hejtmanek suspects WTVS's proposed digital assignment, Channel 41, is being hemmed in by other Channels 40, 41 or 42 in Ontario or other neighboring areas.

The new channels are being given to all TV stations for use during the period of transition to digital transmission. They'll broadcast both analog and digital signals until the transition ends, perhaps seven to 15 years later. By then viewers will have bought new digital TV sets or set-top adapters.

The commission released its proposed table of allotments Aug. 14, and requested public comments by Nov. 22. Public TV engineers have only begun to examine the complex plan, which will require computer analysis. On behalf of public TV, PBS and America's Public Television Stations (APTS) plan to file joint comments and have requested member stations to coordinate comments through them, says Lonna Thompson, APTS director of legal affairs. PBS plans a videoconference about the subject for member stations Sept. 19 at 2 p.m.

Bruce Jacobs, engineering director at North Dakota's Prairie PTV, said "the FCC has done an incredibly good job at dealing with a very complicated issue."

The commission has tried to pack 1,900 new TV channels into the matrix of existing stations, while concentrating almost all of the new ones between Channels 7 and 51, in such a way that the digital transition channels "replicate" the coverage areas of the existing stations' analog signals. The FCC engineers had to work the new channels into this puzzle without causing intereference among stations that will operate on the same channels.

Tough on the rural viewer

Jacobs noted that the FCC's high "replication" figures may be misleading. A station's new digital signal may not equal the actual reach of its existing analog signal even in cases of 100 percent "replication" because analog signals are still watchable, if mediocre, at a distance from the station, beyond the "Grade B contour," while a digital signal with the same nominal reach can't be picked up at all beyond that distance.

In effect, viewers living far from stations may not be able to eke out even a mediocre picture from the digital stations.

At the same time, the addition of the new digital channels will crowd out some number of the "translator" stations that retransmit TV stations into remote areas.

Harvey Arnold, associate director of North Carolina's PTV network, noted that the FCC appears to be open to new applications for vacant noncommercial channels, which gives hope for operators of translators that are now proposed to be blitzed out of existence in many areas. Converting a translator to a full broadcast station would protect it, he says, though the addition of the new TV station would cause extensive ripple effects on other channel assignments.

The FCC figures may also be misleading in another way. To "replicate" stations' present coverage areas, the FCC in some cases assigned UHF channels requiring unrealistically high transmitter power, Jacobs noted. A transmitter with 1.2 megawatts is the largest practical transmitter, he estimated. But the FCC calculated the reach of Seattle's KCTS assuming a 2.9 megawatt transmitter. With a smaller transmitter its digital coverage area would fall short of its present viewing area.

Where interference occurs between stations and limits their signal reach, the FCC proposes to let stations make agreements--and even exchange payments--to reduce transmitter power.

A major objective for packing the new digital transition stations into Channels 7-51 is that the federal government will then be able to redeploy present Channels 52-69 with less shifting of stations when the transition period is over. Congressional leaders want to sell of the upper channels to help reduce the federal deficit, and pocket-phone companies want to acquire the spectrum.


To Current's home page

Current Briefing on the transition to digital and HDTV.

Three public TV stations plan to operate experimental digital transmitters.


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