A revised transcript of radio transmissions by a Soviet fighter pilot shows that he fired "cannon bursts" in the direction of a Korean Air Lines passenger plane six minutes before he launched two heat-seeking missiles that downed the 747 jumbo jet.

The unexpected disclosure yesterday by the State Department raises new questions about whether the Soviets, as they repeatedly have claimed, did try to warn the 747 pilot that he had strayed far into Soviet airspace.

It also leaves unclear whether those shots were aimed at the plane in an initial effort to disable it or force it down, or whether they were an ineffective means of getting the 747 pilot's attention.

In releasing the new transcript and its three revisions, however, the State Department maintained that the additional analysis of the transmission tapes "reinforces our belief that the totality of the events remains exactly as stated by the U.S. and Japan. The Korean airliner was not aware of the Soviet fighters, nor was it aware that any warning was given. The Soviets consciously made the decision to shoot down the aircraft . . . an unarmed civilian airliner, and it cost the lives of 269 innocent people."

A key question is whether the bursts of machine gun or cannon fire were ordinary bullets, which the 747 pilot was apt not to have seen at night, or were highly illuminated tracer bullets, normally visible.

"If they were all tracers, it's inconceivable that he the 747 pilot would have missed all those tracers going by. But if they were shots that are just regular, normal rounds, they're not visible," said Sen. John Glenn (D-Ohio), a former Marine Corps fighter pilot and astronaut.

Glenn, talking with reporters in Ohio Friday, said visibility also would depend on the location from which the tracers were fired and how close the fighter plane was to the airliner.

The State Department noted that the new transcript "does not indicate whether the cannon shots were aimed at the KAL plane or were tracer rounds."

The department also pointed out that transmissions between the 747 pilot and Japan's Narita air traffic control center continued normally until four minutes before the plane was shot down by an Su15 fighter.

Those transmissions, confirmed by the Japanese foreign ministry, give no indication that the Korean pilot saw any tracers or machine gun fire or had any indication that anything was wrong.

Since the airliner was downed Aug. 31, the Soviet Union has said repeatedly that its interceptor pilots "made warning shots with tracer shells along the route of the intruder plane" as a warning signal that "is envisaged by international rules."

The United States, using the version of the tape recordings played at the United Nations last Tuesday, had steadfastly maintained that there is no evidence that shots of any kind were fired before the missile launch and none that the Soviets had attempted to warn or force down the plane.

Addressing the U.N. Security Council Tuesday, U.S. Ambassador Jeane J. Kirkpatrick said that "contrary to Soviet statements, the pilot makes no mention of firing any warning shots--only the firing of the missiles which, he said, struck the target."

Kirkpatrick was relying on the version of the transcript that, until yesterday, was the official translation of communications between three Soviet fighter pilots and their ground controllers. The communications were monitored by military electronic listening posts in Japan and translated from Russian to Japanese to English.

The State Department revealed yesterday that, as part of a U.S. government policy "to develop full information on the tragic shootdown of KAL 007 by Soviet forces on Aug. 31, U.S. government experts have continued to review the poor quality transmission on the tape which was played at the United Nations Security Council Sept. 6."

The department said that the review is finished and that, after "efforts at electronic enhancement and hundreds of replays," linguists "were able to interpret three passages more clearly."

In the first tape released by the U.S. government, a phrase originally translated to indicate that the pilot who fired the missiles said, "I have enough time," has been revised to say, "They do not see me."

This transmission was made at 18:19.08 Greenwich Mean Time (GMT), about seven minutes before the missiles were fired. It occurred after the Su15 pilot reported that he could see the navigation and strobe lights of "the target" and was closing in, presumably from the rear.

It also appears to have taken place as the Su15 pilot had his aiming system "locked on" the 747. A minute later, the Soviet pilot reported that the lock-on was turned off and said, "I'm approaching the target."

The second transcript change involves a transmission seconds later, at 18:20.49, when, the State Department said, the Su15 pilot reported, "I am firing cannon bursts." Previously, the department had said that phrase was "unintelligible."

At 18:22.02, the Soviet pilot reported that "the target is decreasing speed." This occurred about the same time the 747 climbed from 33,000 feet to 35,000 feet.

At 18:15, the 747 pilot had requested clearance from Narita ground control to go to the higher altitude. He received clearance at 1820 and reported three minutes later that he was at the higher altitude.

That was the last clear transmission from the 747. There is no indication that the Korean pilot was changing altitude because he had seen something troublesome, but there is no explanation for why he chose to climb then.

The final transcript change involved a translation at 18:23.37 in which the State Department now says the Soviet pilot was referring to trying "rockets," rather than the singular "rocket" initially reported.

The missiles were fired at 18:26.20, with the pilot reporting two seconds later, "The target is destroyed."

About 30 seconds after that report, the 747 radioed its call sign, KAL 007, to Narita and then the signal became "noisy and weak," according to Japanese records supplied by the foreign ministry. Those records were attached to the State Department document released yesterday.

Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) said yesterday that he had talked with Secretary of State George P. Shultz about the transcripts and praised the Reagan administration for its effort to squeeze every "last bit of conversation" out of the tapes and for releasing the new information as soon as it was available.

"Even if you accept the idea that these were warning shots--perhaps they were tracers that the Russians claim to have fired--it is still no justification by any stretch of the imagination for downing a civilian airliner . . . . I do not think it changes the gruesome nature of the Soviet assault," Baker said on "Face the Nation" (CBS, WDVM).

Asked whether he suspected that the Koreans may have been on an intelligence mission, Baker said he had "the assurance absolutely" that there was no U.S. complicity.

"I cannot say for the Korean government because I don't know. But I have no reason to believe there was any intelligence mission by the Korean government in connection with this airline," he said.

On Saturday, the unidentified pilot who fired the missiles appeared on Soviet television and reiterated that he had fired "four tracer shells right next to him the airliner , but there was no reaction."

The pilot said these shells could be seen for "many kilometers." The Soviets, however, also have claimed that visibility was poor, which might contradict the claim that the tracers should have been seen easily. The United States has said the weather was good.