Al-Nuaimi, M.O.; Charnley, M.: 'Simultaneous voice and data transmission in private mobile radio using a narrowband fm channel', IEE Proceedings F (Communications, Radar and Signal Processing), 1988, 135, (5), p. 439-449, DOI: 10.1049/ip-f-1.1988.0051
IET Digital Library, https://digital-library.theiet.org/;jsessionid=5cn5g72e638qa.x-iet-live-01content/journals/10.1049/ip-f-1.1988.0051