Interference of the GPS signal often caused by the bouncing or reflecting of the signals from surrounding objects. Its effect is similar to "ghosting" on a television screen. It occurs when some of the signals arriving at an antenna have followed an indirect path. A signal taking the longer path gives a larger distance measurement to the satellite. This means that it also gives an inaccurate carrier phase value. It can be the most serious error to affect GPS surveying. While some multipath conditions cause errors of a few centimeters, others cause errors of a few meters. Bad multipath conditions can cause a short static session to fail completely.