The test methods described in this Part 3 are general and are applicable to simulated systems comprising two or more sub-systems. These tests, which are described in subsequent sections, cover the transmission performance of systems used for the transmission of frequency division multiplex (f. d. m.) telephony, monochrome and colour television, sound programme and baseband digital information. This Part 3 should be used in conjunction with Part 1, Measurements Common to Sub-systems and Simulated Radio-relay Systems.