Border Dispute

Interference from Mexican AM stations bodes ill for DTV

The U.S. wants Mexico to turn down the volume. American officials charge that the Mexican government is violating an 18-year-old treaty by letting a trio of Baja AM stations ramp up their power—by as much as 80 times their previous levels—knocking out huge blocks of the listening audience for ABC/Disney stations in Los Angeles and San Francisco.

More important, Mexico's reluctance to power down doesn't bode well for digital TV in America. In the next few years, critical discussions will be required to untangle interference issues as TV stations in both countries switch to all-digital operation.

The signals of the three radio stations, located in the cities of Tijuana, Tecate, and Ensenada, are so strong that listeners of a dozen AM stations in the U.S.—as far away as WBBM Chicago—are bothered by Spanish-language programming in the background. In all, Disney officials estimate that 50 million Americans are suffering interference because of the Mexican power boost.

To underscore the importance of the U.S. message, a U.S. ambassador and FCC Commissioner Michael Copps jetted to Mexico City on April 16 to meet with Geronimo Guttierrez, undersecretary for North American Affairs, and Jorge Alvarez Hoth, undersecretary for communications. Secretary of State Colin Powell has twice written to Mexican Secretary of Foreign Relations Luis Ernesto Derbez insisting that the Mexican government solve the problem.

"This is important not just because of the current situation but for how well we will be able to work with Mexico going forward," says David Gross, U.S. ambassador-at-large for international communications. "Traditionally, we've worked very well with the Mexicans." However, he had no explanation for the stations' unwillingness to power down.

Their reluctance has U.S. officials stumped. Last fall, Mexican officials permitted the stations, located just south of the California border, to switch to new channels and increase power radically, all without coordinating the switch with U.S. regulators as required by a 1986 treaty.

If Mexico's indifference continues, the already difficult transition to DTV could become more encumbered with interference issues, Gross says. Right now, most TV stations are transmitting at power levels too low to cover their entire market. When they switch to full power in the next few years, interference problems inevitably will pop up between stations within the U.S. and on both sides of the Mexican and Canadian borders.

Mexican officials deny that they are dragging their feet. The FCC, they say, is reviewing a draft of their plan for settling the problem, which calls for tweaking signals of both Mexican and U.S. stations. Says Miguel Monte Ruvieo, spokesman for the Mexican embassy, "We're working hard to find a solution acceptable on both sides of the border."

Unless the U.S. stands firm, DTV stations in California, Arizona, New Mexico, and Texas could face years-long bureaucratic disputes over interference, warns David Donovan, president of the Association for Maximum Service Television, the U.S. DTV trade group.

Interference is a headache in the analog world because of the "ghosting" or "snow" it creates on viewers' screens. But DTV receivers, which are essentially computer microprocessors, can't make sense of two signals from different stations, so interference breaks a picture into indecipherable pixilated squares or makes a screen go blank.

One big question is why Mexico allowed the stations to boost their power in first place. Executives from the affected U.S. stations told Gross they believe the huge incursion into American markets is intentional. The programming appears targeted at Hispanics living in the U.S., not just audiences in Mexico. What's more, the three stations are located next to the Gulf of California, which divides the Baja peninsula from the Mexican mainland. Positioning them near such a big body of water allows the stations greater coverage areas than would otherwise be possible, because bouncing signals off water magnifies their strength.

Intentional or not, Gross insists that the Mexican stations are obligated to cut back their power: "The problem is of Mexican creation, and they have the tools to solve it."