Analyzing Frequency Content

Question: When I look into a analog signal in frequency domain (FFT), I see harmonics with certain dB. What I also see (which I shouldn’t) is some noise (!!) in between the harmonics with certain dB. What is this noise ?

Answer: Thank you for the question on analyzing frequency content with an oscilloscope. Depending upon your signal, instrument setup and other factors, there are a number of possibilities as to why you are seeing noise between the signal. As a general rule of thumb, to minimize noise coupling into the scope I first try to ensure proper grounding with short lead lengths. Depending on the signal type, you can also perform filtering or post-processing through some averaging techniques to reduce noise. Again, without knowing anything about the signal or your setup, these are some general considerations that may or may not be relevant.

I would, however, recommend a very nice application note on using Tektronix oscilloscopes for FFT analysis. You can download the application note here.

I hope this helps and thanks again for the question.

Advertisements
Explore posts in the same categories: Ask Scope Guru Q/A, Uncategorized

Tags: ,

You can comment below, or link to this permanent URL from your own site.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s


%d bloggers like this: