Data conversion between EUROCOM D/1 data modes and the CCITT V.110 bit rate adaptation

Abstract

An analog interface between a tactical network and the PIT-network passes speech signals reasonably well, but limits very much the possibilities of data connections. Voiceband modem signals can also pass the interface, but due to the poor quality of 16 kb/s CVSD (continuously variable slope delta modulation) voice channel, the capacity is limited to 1200 b/s. The EUROCOM D/1 standard offers possibilities to transfer data at 50-2400 b/s using sampling and RMVD (running majority voting detection) or at 2400-9600 b/s using BCH-coded data blocks. There are many ways to transfer data at those rates over a fixed network, but they all need the data to be converted at the interface. With the existing equipment this would mean that two terminals are needed for every data connection. The amount of equipment and associated operating personnel makes such an interconnection point a quite expensive and not easily replaceable resource. The developed gateway gives also the possibility to transcode data signals between the tactical network and a fixed network instead of using an intermediate conversion to voiceband. The authors discuss how to convert data between EUROCOM D/1 RMVD/BCH-codes and CCITT V.110/X.30 ISDN bit rate adaptation. Digital conversion at the interface will need much less processing capacity than an intermediate conversion to voiceband. It is also expected to become an economic way of interconnecting, when the use of ISDN for data transmission will increase in the 90s.<>