Abstract: Determining properties associated with signal sources based on measured or observed signal values detected at devices are disclosed. Specifically, a value associated with a signal detected at a device is determined. Based on a type of the device, the determined value is transformed into a normalized value with respect to a reference value determined for a reference device. A property of the device with respect to a source of the signal is determined based at least in part on the normalized value. For example, the determined property may comprise a presence, position, location, distance, motion, rotation, etc., of the device with respect to the source of the signal.