Ultrasonic positioning method of active long-range radio-frequency electronic label

An ultrasonic positioning method of active long-distance radio frequency electronic countermark includes obtaining a positioning command on certain countermark by reader from system, sending the positioning command on assigned countermark through radio frequency wave and sending ultrasonic wave pulse by reader simultaneously, starting up time and stopping it till ultrasonic wave signal is received by receiving circuit, using timer value as propagation time of sound wave, sending said value to reader by radio frequency through countermark for finishing a complete answer and response course and obtaining distance by multiplying sound speed with propagation time .