Signal processing for through-the-Earth radio communication

Author

Raab, Frederick H. ; Joughin, Ian R.

Author_Institution

Green Mountain Radio Research Company, Colchester, VT, USA

Volume

43

Issue

12

fYear

1995

fDate

12/1/1995 12:00:00 AM

Firstpage

2995

Lastpage

3003

Abstract

Through-the-Earth (TE) propagation subjects a radio signal to considerable attenuation. The uplink signal must, however, be detected in the presence of full-strength atmospheric noise. Consequently, through-the-Earth communication systems are generally restricted to relatively low data rates. The electromagnetic characteristics of the TE signal differ from those of the surface-propagating noise. In addition, much of the energy in low-frequency noise is contained in discrete impulses. This paper describes an integrated combination of adaptive noise cancellation (ANC), maximum-likelihood detection (MLD), nonlinear processing (NLP), and decision-aided feedback (DAFB) that can be used to combat atmospheric noise in TEC systems. Tests with real VLF noise demonstrate a 10-to-24 dB improvement in SNR. The reduced effective noise level allows higher data rates, greater depth of operation, smaller transmitters, and/or smaller antennas

Keywords

atmospherics; automatic repeat request; electromagnetic wave absorption; interference suppression; maximum likelihood detection; radiocommunication; signal processing; 10 to 24 dB; SNR; VLF noise; adaptive noise cancellation; antennas; atmospheric noise; decision-aided feedback; depth; discrete impulses; electromagnetic characteristics; low data rates; low-frequency noise; maximum-likelihood detection; nonlinear processing; radio signal attenuation; signal processing; surface-propagating noise; tests; through-the-Earth communication systems; through-the-Earth radio communication; transmitters; uplink signal detection; Attenuation; Electromagnetic interference; Electromagnetic propagation; Feedback; Low-frequency noise; Maximum likelihood detection; Noise cancellation; Radio communication; Signal processing; Tellurium;

fLanguage

English

Journal_Title

Communications, IEEE Transactions on

Publisher

ieee

ISSN

0090-6778

Type

jour

DOI

10.1109/26.477502

Filename

477502