ROBERT Shad Northshield was as distraught as anyone over what happened in Chicago last August--but for different reasons than most people.

Like millions of others, he was awed by the martial atmosphere which brooded over the city during the convention and the brutality of Chicago's police force. But from his professional point of view--as producer of NBC's Huntley-Brinkley Report -- Northshield was as much disturbed by the violent reaction to NBC's coverage of Chicago.

In the aftermath of the convention, TV newsmen were berated by the police and the public as much as the police had been by the media or the hippies and yippies had been by everyone all along.

Mayor Daley produced his own version of Chicago--"The Strategy of Confrontation" -- starring his police department, and in it charged that the news media "responded with surprising naivete and were incredibly misused." Letters from angry citizens--almost unanimously critical of the networks--poured into the studios of NBC and CBS, and into the office of the FCC as well, prompting an investigation of the major networks' coverage.

Harry Reasoner reported on CBS's magazine-format "60 Minutes" that the letters CBS received ran 11 to one against the network's coverage. At NBC, the ratio was even larger.

The brunt of this criticism was felt more acutely by Shad Northshield than anyone else at NBC, for he alone was responsible for NBC's coverage of events outside the convention hall. And to him it was all a bit perplexing.

Northshield probably has more to do with what comes out of the NBC news department than any other one man. His judgment determines exactly what Chet Huntley and David Brinkley read on the air every weekday evening at 6:30 p.m. He is acutely aware that his audience is in the millions and that he is a very strong influence on their opinions. That makes him a powerful man, and he knows it. On election night in NBC's election central control booth, he bragged jokingly that he could get Nixon to concede just by having Chet or David announce that Humphrey had carried California and was now NBC's projected winner.

HE IS A big man with a heavy face and a self-confident, nearly smug air. But he becomes defensive when he talks about Chicago, and it is obvious that he has become sensitive to criticism about his role there.

He is used to being loved by the viewing public -- though the only viewers who probably even know he exists are the few who stay tuned to Huntley-Brinkley after the news is over to hear the snatch of Beethoven as the credits roll up the screen. Huntley and Brinkley have always been those two congenial fellows with the wry wit who make digestion a little bit easier every night after dinner. They became something quite different during the Democratic convention. Their public turned on them, criticized them, and Northshield wonders why.

He admits he made a mistake in airing the amount of footage he did of policemen flailing nightsticks against protesters. But that was something that could not be helped in Chicago.

NBC and the rest of the networks had to fight logistics in Chicago that were just as trying as the run-ins with over-zealous patrolmen. A telephone strike, which many media people claimed was sustained to hamper news coverage of the convention, had crippled communications around the city. One vital consequence was that there could be no live coverage of events outside the convention itself. Everything NBC aired had to be video-taped and rushed back to tre network control booth in the amphitheatre.

There Northshield -- surrounded by two dozen blank monitors that had been intended to carry outside events live--supervised a rapid editing before the film was finally aired.

The result was that coverage of events outside the amphitheatre consisted of long, uninterrupted film sequences shot understandably when there was something happening -- when the clashes between police and protesters reached their height. The same films were aired over and over again whenever Chet or David referred back to the events, as after Senator Ribicoff blasted Mayor Daley for running a police state. Consequently, both the intensity and the frequency of the clashes may have seemed greater than they were.

But Northshield considers this an unfortunate consequence of the events. Police brutality was a fact, which justified exposing it and condemning it. That is precisely what NBC's reporters did.

ON THE NIGHT of August 26, NBC's camera crew was sent to Lincoln Park, where the first real confrontation between police and protesters was expected to take place. The demonstrators were determined to spend the night there; the police had been instructed to run them out.