HOUSTON (AP) _ The U.S. Border Patrol is turning to high technology in efforts to stem the flow of illegal aliens along the Mexican border.

A $100,000 four-wheel-drive Dodge Ramcharger, now on display at the 92nd annual International Association of Chiefs of Police Conference, looks like any other green-and-white U.S. Border Patrol vehicle.

Then the roof slides open, a periscope-like device begins creeping into the air, a television monitor comes to life in the cab and infrared heat detectors atop a mechanical arm begin sending out invisible signals.

''All you try to be is a little bit more sophisticated than they are,'' George Van Horn, a designer of the device, said of efforts against those who would smuggle aliens into the country.

The vehicle has been on the job in Arizona in the Nogales and Douglas areas since April, Van Horn said. It took two months to decide what was wanted on the truck, and now Van Horn is hoping to be able to build 10 more of them.

''They're worth their weight in gold,'' said Jorge Garza, a Border Patrol officer in Laredo, Texas.

The initial operations using the new truck netted about 10 aliens a night, Van Horn said. ''It'll pay for itself,'' he said.

The telescoping antenna, powered by an air compressor in the cargo area of the truck and armed with the sensors, can extend up to 25 feet into the air and has a range of four miles.

One agent, watching the small television monitor while sitting behind the truck's steering wheel, can direct other agents on all-terrain motorcycles to the illegal aliens trying to get into the country under cover of darkness.

''It has almost 100 percent accuracy at 21/2 miles,'' Van Horn said. ''And the guy inside never has to leave his vehicle.''

One of the requirements facing engineers was that the truck be rapidly mobile and had to look like other Border Patrol vehicles, he said.

Although the truck is just about hand-made, Van Horn said he and other research and development technicians who assembled it at Fort Huachuca, Ariz., tried to equip it with parts available ''right off the shelf.''

The ability of agents to zero in on aliens from a great distance is needed to combat smugglers who also equip themselves with heat-seeking devices to hunt the hunters.

''Their budget is greater than ours,'' Van Horn said with a laugh.

The technology is becoming even more sophisticated, he said, with buried radar along the border, heartbeat detectors and airborne detection systems under development.