Because of the surface of the earth is not a plane. there may be some errors in the conventional ultra-short wave passive TDOA location method using plane coordinates. In order to use the geodetic longitude and latitude coordinates directly for TDOA location. a series of spherical distance TDOA location models based on spherical two-point distance calculation were proposed. https://lockdownsecuritycanada.shop/product-category/car-alarm-with-remote-starter/