In television systems, a test signal consisting of a line bar (125 ns rise time and fall time,) a 2T pulse (250 ns half-amplitude duration,) a 12. 5T (1. 5625 microseconds half-amplitude duration) chrominance pulse, and a five-riser staircase signal modulated by the color subcarrier having a peak-to-peak amplitude of 40 IRE units superimposed upon standard synchronizing and blanking signals. Reference 'A' and 'B' are the measurement points utilized in the measurement of insertion gain and insertion-gain variation.