Standards of the DIN EN 60728 series deal with cable networks including equipment and associated methods of measurement for headend reception, processing and distribution of television signals, sound signals and their associated data signals and for processing, interfacing and transmitting all kinds of signals for interactive services using all applicable transmission media. This part of IEC 60728-3-1 of the standard series is a supplement to IEC 60728-3 applying to all wide-band amplifiers. It describes measurement methods for operating characteristics, defines performance levels to be indicated by manufacturers and minimum requirements are specified. The supplementary IEC 60728-3-1 deals with the peculiarities of digitally modulated transmission methods. The non-linearity measurement methods described for this purpose apply for cable networks which carry only digitally modulated television signals, sound signals and signals for interactive services. These methods take into account the specific signal form and behaviour of digitally modulated signals which differ from the analogue broadcast signals represented mainly by the existence of discrete carrier signals. The responsible committee is DKE/K 735 "Kabelnetze und Antennen für Fernsehsignale, Tonsignale und interaktive Dienste" ("Cable networks for television signals, sound signals and interactive services") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.