a) The –40 IRE pulse occurring at the beginning of each line. This pulse signals the picture monitor beam to go back to the left side of the screen and trace another horizontal line of picture information.

b) The portion of the video signal that occurs between the end of one line of signal and the beginning of the next. A negative-going pulse from the blanking signal used to genlock (synchronize) equipment. It begins at the end of the front porch and ends at the beginning of the back porch.