Facsimile transmission via HF radio

The authors examine the feasibility of transmitting facsimile (FAX) over radio voice-channels using existing machines and existing radio installations. CCITT Groups 1, 2, and 3 FAX were tested on simulated high-frequency (HF) channels using the US government´s HF simulator at Ft. Monmouth, NJ. Tests included both the premessage exchange and the message portion of the FAX transmission. Test results show that the FAX integral wire-line model used for Group 3 operation does not work well on realistic, long-haul, HF channels even at the minimum fallback rate of 2400 b/s. Group 2 FAX also fails for most of the cases simulated. Group 1 FAX produces documents on most simulated channels although the quality of the document degrades as the impairments become severe. The degraded documents, however, are usable in most cases