Applying EMAT for Ultrasonic Communication Through Steel Plates and Pipes

Ultrasonic communication methods have been used for sending data through elastic solids such as steel pipes or plates to overcome physical hurdles that hamper the conventional communication methods (wired and RF wireless). EMAT (Electro Magnetic Acoustic Transducer), an ultrasonic signal generation technique that generates different modes of waveform, is particularly useful for hot, cold, or dry environments, which overcome many of the issues faced by conventional PZT ultrasonic probes. In this paper, EMAT is used as the transmitter for noncontact ultrasonic signal generation and PZT is used as the receiver for the communication system. This system is designed to assess the efficiency of Lamb waves and to examine Bit Error Rate (BER) of digital communication. The communication system was configured using National Instrument arbitrary waveform generator (AWG) and PXI digital oscilloscope. The accuracy of transmitted information is tested on a 5-foot long stainless-steel plate and pipe. The system operates with the frequency of 414 kHz signal and uses Amplitude-Shift Keying (ASK) modulation for transmission. This method can transfer digital data in presence of undesirable multipath effect with bit rates of 20 kbps and 40 kbps without any error.