Sensitivity Time Control

The sensitivity time control (STC) is a circuit in a radar device, which affects the dynamics of the receiver. It is a time dependent gain control, causes a dynamic compression. It is often spoken of an STC. Some use radar equipment manufacturer for this function in your device documentation and the term Gain Time Control (GTC ).

On a radar receiver very high demands are made. He must be able to handle extremely small signals and may at the same time not be overridden by very large signals. In a radar echo signals are caused by very small reception services usually by very distant objects. Very far from the same time means that the runtime is relatively great with respect to the echo signals from the vicinity of the radar.

An amplifier with gain STC function is increased continuously during the receiving time. The gain factor is also dependent on time, and hence of the distance R. Ideally, the gain factor V to R4 proportionally. In practice this characteristic is often approximated by the exponential function resulting in charging of a capacitor. As opposed to a limiting signal, but must also have an after compression (although substantially reduced ) difference between the different sizes of input signals remain recognizable.

As at close range outweigh the fixed target echoes, which usually additionally much larger geometric proportions than aircraft, a control area is used up to 30 dB. The size of the fixed target echoes, which vary depending on the current azimuth angle of the antenna dictates the size of the reference STC curve. In the very long transmit pulses of radar devices that work with the pulse compression method, it must be ensured that the change in the gain does not lead to changes in the pulse shape. Therefore, to measure the level of modern radar receiver fixed target echoes for each range cell and then set the STC attenuation depends on the azimuth angle and the distance. In most cases, however, is only one of several standard curves used with differently large pitch.

An in effect manually controlled STC function is used in radar navigation equipment for ships and boats, in order to suppress Seaclutter. There being only the gain of the radar receiver is reduced so that smaller and weaker signals can be suppressed.

• Radar