RFID radio positioning method based on phase difference ranging

Abstract

A RFID radio positioning method by utilizing phase-difference to measure out distance includes binding radio frequency countermark on object to be measured, setting at least two readers on positions within 1-10 meter surrounding said object, knowing position of each reader and distance between the two, emitting and receiving electromagnetic wave by each reader through its own antenna, measuring phase-difference of emission phase and reception phase to confirm distance between radio frequency countermark to each reader and calculating out position of said countermark according to geometric relation of said countermark to readers.

Description

technical field [0001] The invention belongs to the field of wireless positioning, in particular to the application field of using RFID (radio frequency identification tag) for precise positioning. Background technique [0002] Wireless positioning technology is to measure some parameters of the received radio waves, and based on this, the position of the measured object can be judged according to a specific algorithm. The measurement parameters generally include the transmission time, amplitude, phase and angle of arrival of the test signal, and the positioning accuracy depends on the measurement method. At present, the maturity and development of wireless communication technology has led to the emergence of emerging wireless services, and more and more applications require automatic positioning services. Therefore, there are more and more types of wireless positioning technologies, and their applications are becoming more and more extensive. Commonly used wireless positi...

AI Technical Summary

Problems solved by technology

However, the performance and availability of the GPS system show a sharp decline in indoor or densely built areas, and its positioning speed is relatively slow, and it is also expensive to deploy.

[0004] (2) Cellular positioning technology: Cellular networks such as GSM and CDMA all support positioning technology, but factors such as non-line-of-sight (NLOS) propagation, multipath effects, and multiple access interference reduce the positioning accuracy, and involve user privacy issues, so that Its promotion is subject to certain restrictions

[0005] (3) Infrared technology: The active tag based on infrared technology developed by AT&T Cambridge research laboratory can be used for indoor object positioning, but it requires that the object must be in a straight line with the infrared reader, and the positioning distance is too close, thus limiting its use. continue to develop

The disadvantage is that the system investment is large

LANDMARC is stable and less affected by environmental changes. However, at present, this system can only provide two-dimensional indoor positioning

[0030] However, these three methods are all based on RSSI technology, that is, using radio frequency signal strength data as the basis for positioning, which is easily affected by various interferences, and the measurement accuracy is not high, and they all use active tags, which makes the system more costly.

Images