TABLE OF CONTENTS In modern electronic and telecommunication systems, transmission media such as cables and wave guides, free space radio links and fibre optic cable systems are used. These systems today carry a wide range of frequencies from a few kilohertz to gigahertz and optical range signals. These systems, such as cables or wave guides, are characterised by distributed parameters and behave in a slightly different manner than the systems that are designed by using the lumped parameter systems. For this reason transmission measurements need be carried out using specially designed instruments. In practical environments, engineers and technicians use different types of instruments for the measurement of power, field strength and relative amplitude of signals transmitted, as well as other important parameters of the medium such as signal reflections and loss. As the length of a transmission medium becomes long compared with the wavelengths of the signals transmitted, it becomes very important to measure these parameters accurately. At microwave frequencies the behaviour of transmission media and accessories becomes very critical, thus the accurate measurement of parameters related to transmission becomes quite crucial to the operation of a system.
In the digital telecommunication networks, the present industry uses technologies such as digital subscribe loop (DSL), plesiochronous digital hierarchy (PDH), synchronous digital hierarchy (SDH) and synchronous optical networks (SONET). In these systems digital instruments are utilised for nanosecond and picosecond order timing measurements to guarantee the quality of transport. These have created a need for a very sophisticated digital transmission measurement test system.
