Abstract
We propose an asynchronous acoustic chirp slope keying to map short bit sequences on single or multiple bands without preamble or error correction coding on the physical layer. We introduce a symbol detection scheme in the demodulator that uses the superposed matched filter results of up and down chirp references to estimate the symbol timing, which removes the requirement of a preamble for symbol synchronization. Details of the implementation are disclosed and discussed, and the performance is verified in a pool measurement on laboratory scale, as well as the simulation for a channel containing Rayleigh fading and Additive White Gaussian Noise. For time-bandwidth products (TB) of 50 in single band mode, a raw data rate of 100 bit/s is simulated to achieve bit error rates (BER) below 0.001 for signal-to-noise ratios above −6 dB. In dual-band mode, for TB of 25 and a data rate of 200 bit/s, the same bit error level was achieved for signal-to-noise ratios above 0 dB. The simulated packet error rates (PER) follow the general behavior of the BER, but with a higher error probability, which increases with the length of bits in each packet.
Highlights
Evidence suggests that the general idea to sweep the frequency of a carrier to transmit information may be as old as life on earth [27], but the first modern record we found is Hüttmann et al.’s patent for a distance measurement method from 1940 [28]
In the following we describe the structure of our communication signal chain in detail, to embed our contribution to the demodulation process properly and fully disclose our method for ease of comparison
The noise floor confirms the assumption of additive white Gaussian noise (AWGN) outside of the transmission, with an approximate
Summary
While there are several communications systems for deep open water communications available, where offshore industries and naval warfare have accelerated technological advancement, shallow water still challenges communication attempts after over a hundred years of research [1,2,3]. This may stem from the strongly selective frequency fading, high phase noise and fast echoes and for moving nodes, due to a strong Doppler effect which characterizes the instability of the acoustic underwater channel [4,5,6,7,8,9]. The shallower the channel is, the more pronounced this inhibitions become
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
