Transmission performance of digital FM utilizing jointly Gaussian filter and Nyquist-III filter for a premodulation filter

Abstract

In this paper, we propose a new scheme of digital frequency modulation that jointly utilizes a Nyquist III filter and a Gaussian filter for a premodulation filter. In this scheme, the phase transition and the phase trajectory during the symbol interval are settled independently of each other by setting the parameters of the two filters, and it is thus possible to improve the transmission performance by controlling the parameters of these filters appropriately. Furthermore, this scheme has an additional merit of increasing the minimum signal-space distance d2min above 2.0, and it has the possibility of improving BER performance. When the bandwidth of the signal widens with the increase of d2min, it is possible to adjust the signal spectrum by utilizing the Gaussian filter. Thus, it is possible to obtain superior transmission performance by setting the parameters of the two filters appropriately and employing a suitable detection method. Furthermore, we show that the transmission performance of this scheme is as good as GMSK in an AWGN environment. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 3, 80(9): 1–10, 1997