"It's a different world up here," said Georgia state trooper Jeff Bacon, as he patrolled Peachtree Street.

A man in a green Volvo balled his fist up at the passing patrol car. Another motorist gave a friendly wave.

Jeff Bacon would rather have been patrolling his old beat in Marietta and farming his 100 acres of soybeans in Eastman. But his way of life is a casualty of Atlanta's stepped-up war on crime.

Bacon was one of 50 state troopers assigned to the city this week in a move aimed at curbing the summer's spiral of robberies and murders. The move already has taken on a political tinge.

Some observers see Gov. George Busbee pushing the troopers off on Mayor Maynard Jackson in an attempt to smudge Jackson's record as a crime-fighter. Both men are regarded as possible contenders against Sen. Herman Talmadge in next year's Democratic primary.

Busbee has denied he will run. Jackson's candidacy, however, has reached the polling point. He has hired Washington pollster William R. Hamilton to find out if Georgians are ready to send a black man to the U.S. Senate.

Missing among the 49 questions in Hamilton's poll is one on how well Atlanta's mayor deals with crime.

Jackson says he did not consider the political angles when Busbee suggested the troopers and the mayor requested them. "I am not into, and never have been into, political implications of decisions I make for this city," he said.

Jackson said he is not embarrassed by the troopers' presence. State police have been assigned to other Georgia cities in the past, he noted, and Atlanta is not alone in its struggle with crime. "Crime is up nationwide," he said.

Some crime experts are wondering if high crime isn't a Sun Belt sickness.

Last year, Atlanta experienced more crime per capita than any of the other 40 largest cities, according to FBI estimates. So far this year, New Orleans leads big cities nationwide with a 37.5 percent increase in crime. Atlanta, with a 29 percent rise, is in second place.

"Dramatic changes in society are often associated with fluctuations in the crime rate," says Eugene Czajkoski, dean of the Florida State University School of Criminology, "and the South undoubtedly in recent years has undergone considerable change."

"All kinds of things are being tried in attempts to reduce crime," Czajkoski said yesterday. "Some of it may border on quackery, but the important thing is that there is a willingness on the part of government to explore a solution to the crime problem."

The willingness in the urban South to explore solutions other than additional manpower may be limited by other factors, including murder tolls.

Last May, New Orleans Mayor Ernest N. (Dutch) Morial pressed Louisiana Gov. Edwin W. Edwards for 50 specially trained troopers to help control the city's violent crime.

As of yesterday, the New Orleans crime wave had subsided, the number of troopers sought had dropped to 25 and a fall training regimen for them was in doubt because money for the project had not been found.

In Atlanta, crime fever still runs high. The city this week recorded its 149th murder, six more than in all of last year.

Last Monday, jazz pianist Joseph B. Booth, photography student Suzette Schutz and another woman, Sandy Smith, were found shot to death in Booth's tidy Peachtree Hills house. Police speculated drug traffic was behind the slayings.

Thursday, the mayor unveiled a new anticrime program, calling for:

Creation of a "court watch" program enlisting citizen volunteers to monitor criminal sentencing, which police here have criticized as being too lenient.

Hiring up to 60 nonsworn officers to work in "community service" posts, freeing regular police for street duty.

Posting city-paid security guards at housing projects and budgeting overtime pay for police, who now are paid only "straight time."

Meanwhile, the city formed a 50-member "police flying squad" from current personnel. It is designed to give high police visibility in high-crime areas.

To the embarrassment of city officials, Atlanta dailies reported the squad drained existing patrol units. Before dawn Thursday, only five patrolmen and a sergeant were on duty in the downtown area, the heart of Atlanta's tourist and convention industry. Thirteen officers had been shifted to the flying squad.

In the crackdown, the city also designated six downtown spots as "neighborhood parks," which means they must close from 11 p.m. to 6 a.m. The areas, including a $9 million patch of green at the Five Points financial district, are havens for street drunks whom Jackson blames for many recent thefts.

The mayor also got a promise of help from former attorney general Griffin B. Bell. Bell, who is returning to his old Atlanta law firm, said he had agreed to serve as special adviser on crime to the mayor.

While getting new help, Jackson also got rid of an old foe -- Police Bureau Director John Inman, who has been paid up to $35,869 a year to do what the mayor said was literally nothing.

Inman resigned Thursday rather than head a training and handgun control program Jackson proposed.

Inman had been a target since Jackson became mayor in 1974, but the Georgia Supreme Court ruled the city had to honor Inman's contract until next March.

"Your free ride on the taxpayers is over," Jackson told Inman in a letter this week. "We need all police personnel to do what they can to help Atlanta's war on crime."

Calling Inman "a parasite at the public trough," Jackson warned, "You will earn your pay or you will be gone."

Thursday, Inman went, "disgusted at the paranoid way the mayor was doing things," his lawyers said.