Step attenuator

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A step attenuator (also called attenuator ) is a classic measuring instrument for comparative measurement of transmission systems .

The step attenuator allows attenuators ( signal attenuations ) to be switched into a transmission path in a controlled and gradual manner. A step attenuator is designed so that it does not have any further uncontrolled influence on the signal.

Step attenuators are available in different designs, for example for low frequency and high frequency applications . Modern computer-controlled step attenuators also contain many additional functions, such as support for automatic measurements. Step attenuators can also be found as additional functions in high-quality measuring devices.

In addition to the application in measurements, step attenuators are used to adjust the level of signal generators. Related to this application is the use of step attenuators as a potentiometer replacement in high-end audio products for audiophiles . The improvement in quality in the audio sector compared to good potentiometers is purely subjective and cannot be measured.

Measuring principle

A measurement with a level attenuator usually takes place in such a way that a signal source is connected once directly to a signal receiver (e.g. a level meter or, in the audio sector, headphones ) via a level attenuator and once via the transmission system to be measured. The output of the step attenuator and the output of the transmission system are alternately switched to the signal receiver. Attenuations are switched on at the step attenuator until the signal from the step attenuator corresponds to the signal from the transmission system (for example, the same level is displayed or the same volume is perceived in the headphones). At this point, the attenuation of the transmission system corresponds to the attenuation set on the step attenuator and can therefore be read directly from the setting of the step attenuator. This reading presupposes that the setting and reading of the step attenuator can take place with sufficient accuracy, that is, that the step attenuator is adjusted or calibrated accordingly .

The advantage of using a step attenuator is that both the signal transmitter / generator used and the signal receiver used do not have to have an absolute measurement accuracy. It is sufficient for the transmitter to work with sufficient stability over the duration of the measurement. For the receiver that reproducible relative differences (for example the volume in headphones) can be perceived with sufficient accuracy over the duration of the measurement.

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