These concepts led to experiments with Low Frequency LORAN in 1945, using a much lower frequency, 180 kHz. A system with three transmitters was set up on the US east coast using long antennas supported by balloons. The experiments demonstrated that the accuracy inherent to the design while working at such low frequencies was simply too great to be useful; operational factors introduced errors that overwhelmed the inherent capabilities. Nevertheless, the three transmitters were re-installed in northern Canada and Alaska for experiments in polar navigation, and ran for three years until shutting down again in March 1950.[18] These experiments demonstrated accuracy on the order of 0.15 microseconds, or about 50 metres (0.031 mi), a great advance over LORAN. Maximum usable range was 1,000 miles (1,600 km) over land and 1,500 miles (2,400 km) on the sea. Using cycle matching, the system demonstrated an accuracy of 160 feet (49 m) at 750 miles (1,210 km).[18] But it was also discovered that the system was very difficult to use and the measurements remained subject to confusion over which cycles to match.