Time base generator

Many signals of interest vary over time at a very rapid rate, but have an underlying periodic nature.

Sounds are modulated into the carrier by modifying the signal, either in amplitude (AM), frequency (FM) or similar techniques.

A typical radar system broadcasts a short pulse of radio signal and then listens for echoes from distant objects.

As the signal travels at the speed of light and has to travel to the target object and back, the distance to the target can be determined by measuring the delay between the broadcast and reception, multiplying the speed of light by that time, and then dividing by two (there and back again).

For instance, an early warning radar like Chain Home (CH) might have a maximum range of 150 kilometres (93 miles), a distance that light will travel out and back in 1 millisecond.

This would be used with a time base generator that pulls the beam across the CRT once every millisecond, starting the sweep when the broadcast signal ends.

If this is displayed on a four-inch CRT and the blip is measured to be 2 inches from the left side, then the target is 0.5 milliseconds away, or about 75 kilometres (47 miles).

A basic oscilloscope typically employs a time base generator, which is controlled with the top dial, while the bottom dial controls the amplification of the signal.