The Federal Communications Commission voted yesterday to immediately freeze allotments of television channels in 30 major metropolitan areas, including the District, while it studies whether the current TV technical standards are outdated.

The freeze, which also affects construction permit applications, will not apply to changes by existing stations or to applications already on file.

"Significant technological advancement in broadcast television appears every generation or so," FCC Chairman Dennis R. Patrick said. "Today we officially embark on a course which may ultimately result in yet another generation of television technology."

One of the advancements Patrick alluded to is high-definition TV, which shows nearly twice the number of horizontal lines that make up a picture on a conventional set, but also requires a broader segment of the frequency than ordinary TV. Other advancements, the commission said, range from fairly modest improvements to revolutionary changes.

The commission also agreed to seek industry comment on the status of advanced television systems and determine what role the government should play in promoting their growth.

The body of television technical standards now in effect was devised in 1941. The FCC said those standards reflect the technological limits of the early days of television and are considered today to limit video and audio quality.

The FCC said it also planned to look at the separation between UHF channel assignments, which were set up so the signal of one television station did not interfere with another. The result, according to Lex Felker, engineering assistant to Patrick, is that there are many unalloted UHF channels. The separations limit the number of UHF assignments in an area to nine of a possible 55.

But Patrick said that before the FCC takes action on advanced systems, it should consider the compatibility with current TVs, the amount of additional spectrum capacity the new systems will require and how much improvement the systems offer