Introduction

On leased circuits, considering that there exist and will come into being other modems with features designed to meet the requirements of Administrations and users, this Recommendation in no way restricts the use of any other modems.

The only group reference pilot frequency which can be used in conjunction with this modem is 104.08 kHz.

The modem is intended to be used on group band circuits not necessarily conforming to [1].

Principal characteristics:

a) transmission of any type of high-speed synchronous data in duplex constant carrier mode on 4-wire (60-108 kHz) group band circuits;

b) primary data signalling rates up to 144 kbit/s;

c) inclusion of an automatic adaptive equalizer;

d) class IV partial response pulse amplitude single sideband signalling and modulation;

e) optional inclusion of an overhead-free multiplexer combining existing data signalling rates;

f) optional voice channel.