A mobile wireless transmitter is detected from location data received for a plurality of wireless transmitters obtained through crowdsourcing or wardriving. Location data is held until sufficient time or enough location data is collected from which movement of a wireless transmitter can be detected. Sets of measurement data for each wireless transmitter are determined from the collected location data. The sets of measurement data may include, e.g., Service Set Identifier (SSID), a round trip time (RTT) variance, and/or a neighbor relationship graph for each wireless transmitter. The mobile wireless transmitter is identified from the sets of measurement data. An almanac database may then be published in which any mobile wireless transmitters are identified or excluded.