The distance measurement check

A variety of techniques relating to determine the distance between the devices is disclosed. The distance between the two devices, one of the devices that may be identified by requiring one or more of the operations for generating a possible result only when present within a predetermined distance from the other device to perform the device is. In some aspects it verified ranging is accomplished through the use of a measurement signal and a response signal. In some aspects, the measurement signal may comprise a random, pseudorandom, or bran static sequence. The responding device is the operation of the measurement signal related to a known function, it is also possible to generate a response signal. The measurement device may perform operations to determine the probability that the response device to operate properly on a measurement signal transmitted by the ranging device to the responding device. Distance measurements, determine the distance, body area network, personal area network