Navigation systems for use in indoor environments may include a navigation system that can calculate a time of flight of signals between a navigation device and a WiFi® Access Point. Such a calculation can be more accurate not just by using more accurate oscillators in devices, but by correcting a relative error between two devices. This relative error may be found by determining a timing offset correction, a difference in accuracy between the navigation device and the WiFi® Access Point. This may be performed by performing a fine frequency estimation on a long training field or by receiving a parts per million (ppm) offset from another device. Once the ppm offset is determined, the accuracy of the navigation device can be improved by a factor of 50 using a series of equations described in the disclosure.