A value of 100 IRE was originally defined to be the range from black to white in a video signal. A value of 0 IRE corresponds to the voltage value of the signal during the blanking period. The sync pulse is normally 40 IRE below this 0 IRE value, so the total range covered from peak to trough of an all white signal would be 140 IRE.
- Robin & Poulin; Michael Robin, Michel Poulin (2000). Digital television fundamentals: design and installation of video and audio systems. McGraw-Hill Professional. p. 17. ISBN 0-07-135581-2.
- "BT.470 : Conventional analogue television systems". International Telecommunications Union. Retrieved 28 August 2012.