Carrier frequency offset estimation for an acoustic-electric channel using 16 QAM modulation

Michael T. Cunningham; Leonard A. Anderson; Kyle R. Wilt; Soumya Chakraborty; Gary J. Saulnier; Henry A. Scarton

doi:10.1117/12.2224366

12 May 2016 Carrier frequency offset estimation for an acoustic-electric channel using 16 QAM modulation

Michael T. Cunningham, Leonard A. Anderson, Kyle R. Wilt, Soumya Chakraborty, Gary J. Saulnier, Henry A. Scarton

Proceedings Volume 9825, Sensors, and Command, Control, Communications, and Intelligence (C3I) Technologies for Homeland Security, Defense, and Law Enforcement Applications XV; 98250P (2016) https://doi.org/10.1117/12.2224366
Event: SPIE Defense + Security, 2016, Baltimore, MD, United States

Abstract

Acoustic-electric channels can be used to send data through metallic barriers, enabling communications where electromagnetic signals are ineffective. This paper considers an acoustic-electric channel that is formed by mounting piezoelectric transducers on metallic barriers that are separated by a thin water layer. The transducers are coupled to the barriers using epoxy and the barriers are positioned to axially-align the PZTs, maximizing energy transfer efficiency. The electrical signals are converted by the transmitting transducers into acoustic waves, which propagate through the elastic walls and water medium to the receiving transducers. The reverberation of the acoustic signals in these channels can produce multipath distortion with a significant delay spread that introduces inter-symbol interference (ISI) into the received signal. While the multipath effects can be severe, the channel does not change rapidly which makes equalization easier. Here we implement a 16-QAM system on this channel, including a method for obtaining accurate carrier frequency offset (CFO) estimates in the presence of the quasi-static multipath propagation. A raised-power approach is considered but found to suffer from excessive data noise resulting from the ISI. An alternative approach that utilizes a pilot tone burst at the start of a data packet is used for CFO estimation and found to be effective. The autocorrelation method is used to estimate the frequency of the received burst. A real-time prototype of the 16 QAM system that uses a Texas Instruments MSP430 microcontroller-based transmitter and a personal computer-based receiver is presented along with performance results.

Citation Download Citation

Michael T. Cunningham, Leonard A. Anderson, Kyle R. Wilt, Soumya Chakraborty, Gary J. Saulnier, and Henry A. Scarton "Carrier frequency offset estimation for an acoustic-electric channel using 16 QAM modulation", Proc. SPIE 9825, Sensors, and Command, Control, Communications, and Intelligence (C3I) Technologies for Homeland Security, Defense, and Law Enforcement Applications XV, 98250P (12 May 2016); https://doi.org/10.1117/12.2224366

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available