An image on a TV screen consists of a number of horizontal lines. All these lines are transmitted to the TV one after another. To reduce flickering, first all even numbered lines are transmitted, and then all odd numbered lines. This is called interlacing. So one image is built of two frames with lines.

To make sure that the TV receiver reconstructs the image in the correct way, there are line synchronization pulses between all the lines and frame synchronization pulses between the different frames. The frame sync pulse after an odd numbered frame is different from the frame sync pulse after an even numbered frame.

Some of the TiePie engineering instruments have special sync pulse separator circuits, that will detect the TV line and frame pulses in a TV signal. These pulses can be used to trigger the measurement, so that a measurement will always start at the beginning of a line, or at the beginning of the even frame or at the beginning of the odd frame.

The options to choose from in the software are:

• TV Line : trigger on a line sync pulse
• TV Frame odd : trigger on an odd frame sync pulse
• TV Frame even : trigger on an even frame sync pulse