An identification is made as to when a device is at an anchor location, which can be a proximity zone along an edge of a dead zone or a location where a signal from a beacon is detected. In response to the device being at an anchor location, recording of crowd sourcing data based on dead reckoning starts. Recording crowd sourcing data based on dead reckoning includes identifying one or more signals received by a device while the device is at each of multiple positions. For each of the multiple positions, both an indication of the position determined based at least in part on dead reckoning and an indication of the one or more signals received while the device is at that position are recorded.
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