On-Off Ratio

The on-off ratio of a pulse train is the ratio of the pulse duration to the pulse spacing. In a pulsed system, such as the transmitter of a radar set, the on-off ratio determines the ratio of peak power to average power and thus is an important characteristic of the performance of such systems (seePULSE ENGINEERING).

When the on-off ratio of the pulses transmitted by a radar set is decreased, the range and measurement accuracy of the radar set are improved, but more energy is consumed. In sampled-data equipment and systems for the transmission and processing of information, an insufficiently high on-off ratio can result in distortion of the information. Pulsed systems are sometimes classified according to their on-off ratio. For example, a distinction is made between radar sets with large (of the order of 10² or 10³) and small (less than 100) on-off ratios.