Measuring filter response using a noise source

in measurement by DP | 2 comments

LeCroy114

KF5OBS writes:

If you own a spectrum analyzer with tracking generator or, even better, a good vector network analyzer, measuring the frequency response of a filter is fairly easy. But there is one old approach using a noise source that can turn any oscilloscope with a FFT spectrum view into a useful tool for determining the frequency response of a filter.

The concept I will outline in this article is absolutely nothing new. Back in the days, engineers and hobbyists would use analog noise sources in combination with a spectrum analyzer to determine the frequency response of a filter. The concept is very simple: the wide-band noise source is connected to the input of the filter and the output of the filter is connected to the input of the spectrum analyzer…

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Comments

  1. This is being a little picky, but the picture that was chosen is from a sine wave sweep, not the noise source. I believe this to be slightly misleading because the noise source results look significantly worse (as they should), but the power is in the fact that you can still clearly see the basic filter shape.

  2. Sebastian (KF5OBS) says:

    @Christopher: No kidding. If you actually read the article, you’ll see that I actually describe exactly that in there.

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