Not sure what you're asking : ) You need a clear line of sight so first check is to see if the remote bridge is visible from the root bridge, us binoculars if it's a long way away.
Second check is to put the bridges in install mode and check the LEDs on the back to see what the signal quality is.
Final check, make sure there are no obstructions near the line of site (in the fresnel zone) which might interfere with the signal. If the bridges are a really long way apart the curvature of the Earth will also have an impact.
