The GBI began operation that year as a two element interferometer in order to test large aperture synthesis arrays and study radio astrometry and interstellar scintillation.

The portable telescope was placed 8 miles (13 km) away from Green Bank site and then moved to 11 miles (18 km) forming a T shape with the length of the bottom arm of the T to be similar to the length of each arm of the Y configuration at Karl G. Jansky Very Large Array (VLA) which was still in a design phase.

The portable telescope was later placed on a mountaintop in Huntersville, West Virginia, 26 miles (42 km) away from Green Bank, which is the same distance of the longest baseline of VLA.

[2] In 1983, the 45-foot (14 m) portable telescope was moved back to Green Bank for another function to become a tracking station for Space VLBI satellites.

The GBI was then used as a two telescope interferometer that operated simultaneously at 2.25 and 8.3 GHz to monitor transient, galactic X-ray binaries, AGN's and Gamma-ray sources.