A
ATTENUATOR, (ATTN)
In the context of spectral analysis this term mostly denotes an input attenuator. "Attenuator Setting" describes the setting of the "input attenuator".
Decreasing the attenuation by 10 dB results in a
noise floor decreased by 10 dB
AUTO, AUTOMATIC
Automatic coupling of device parameters: AUTO. In order to obtain optimum measurement results the measurement parameters need to be set in a specific relation to one another.
This feature allows exact measurements to be made in the majority of spectrum analysis applications within a relatively short time (sweep time) under optimum drive level conditions (mixer level). Automatic coupling should be disabled for special applications such as sensitivity or intermodulation measurements.
AVERAGE NOISE LEVEL
> Noise floor
AVERAGING
A method of smoothing the results of several measurements by combining them and taking the average. Two methods are used:
Noise level with analog averaging:
a lower VBW results in a lower noise figure
(VBW = RBW, VBW = RBW/10, VBW = RBW/100, VBW = RBW/1000)
- Analog (or time-constant) averaging, which is the weighting of the level display by means of the video filter time constant.
Background: This averaging will occur as soon as VBW is set to a smaller value than RBW. In order not to increase the measurement error, the sweep time must be increased.
- Digital averaging, which is the formation of the average of several sweeps from the stored level values for each measurement frequency.
Background: This method does not affect the sweep time. However, this measurement principle bears the risk of major measurement errors.
Spectrum without averaging
Spectrum with digital averaging
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