For instance, static in the signal will affect both sub-signals equally, so it will have no effect on the result. Similarly, changes in overall signal strength as the aircraft approaches the runway, or changes due to fading, will have little effect on the resulting measurement because they would normally affect both channels equally. The system is subject to multipath distortion effects due to the use of multiple frequencies, but because those effects are dependant on the terrain, they are generally fixed in location and can be accounted for through adjustments in the antenna or phase shifters.[1]