Honary, B. and Zolghadr, F. and Darnell, M. (1992) Improved HF modem using convolutional coding. Electronics and Communication Engineering Journal, 4 (2). pp. 73-82. ISSN 0954-0695
Full text not available from this repository.Abstract
The paper describes the design of a digitally implemented modem for use over HF (2-30 MHz) radio channels. As a completely digital approach offers the prospect of a number of significant improvements, a new digital multifrequency-shift-keying (MFSK) modem has been developed that employs a novel digital processing procedure termed code-assisted bit synchronisation (CABS). Signal detection is achieved via a set of noncoherent correlators, whilst symbol synchronisation and error correction are performed using a soft-decision Viterbi decoder. Practical tests of modem show that it operates effectively under both additive white Gaussian noise and real HF channel conditions.