Abstract: At present, small and medium size radio monitoring stations with their low cost, small volume, convenient in maintenance etc advantages are widely applied, have gradually become the industry trend. However, numerous small stadons currently only have monitoring function, doesri t have the direction-finding function, and bring a lot of inconvenfence to the unknown source orientation. So it is particularly important to research method of locating based on TDOA Time Difference of Arrival). This paper discussed the method of calculating unknown source to defined position, based on temporal difference between unknown source and the different stations. Finally, it was implemented with C language.

Key words: TDOA, Hyperbolic, Longitude and latitude, Time position