Applies to television transmitters and transposers operating in accordance with television systems for monochrome and colour transmission employing 625 or 525 lines as described in CCIR publications. Deals with the application of insertion test signal measurement to television transmitters and transposers. This method of measurement is useful for checking the line time performance of the transmitters or transposers during programme service and provides a convenient method of testing transmission performance stability during acceptance tests. May also be used as an alternative means of carrying out some of the line time measurements described in IEC 60244-5 and 60244-9.