Transmission quality of group III facsimile on IDR satellite links with circuit multiplication equipment

The focus of this paper is on ways to improve the quality of Group III facsimile on intermediate data rate (IDR) satellite links. First, we present the results of an evaluation of the quality of Group III (G3) facsimile images transmitted on satellite links through circuit multiplication equipment (CME). Based on the results of this study, we propose a model to relate the facsimile image quality requirements to the bit error ratio (BER) on the link. A procedure is introduced to associate the long-term percentage of error-free pages in G3 facsimile transmission with various bit error probability (BEP) masks used for satellite link design. The intent of this procedure is to provide comparable end-to-end transmission quality for international telephone circuits, irrespective of whether the transmission medium is a satellite link or a fibre-optic cable. It is concluded that, unless the performance objectives of satellite systems significantly exceed those derived from CCITT/ITU-T Recommendation G.826, fibre-optic cables will become the preferred choice for international transmission.