# Sqaure Wave Fourier Transform question

• nissanztt90
In summary, the conversation discusses a question from a recent Physics Lab involving the use of a function generator and spectrum analyzer to perform a Fourier transform on a square wave signal. The discussion focuses on the presence of smaller peaks on a log scale that remain at a constant magnitude compared to the main Fourier peaks that decrease in magnitude. The conversation includes a request for a picture of the spectrum analyzer display and a clarification on the appropriate forum for discussing Fourier transforms.
nissanztt90

## Homework Statement

This is a question from a Physics Lab i recently completed. We used a function generator to provide a signal to a spectrum analyzer that performed a Fourier transform on the signal. In this case the signal was a square wave. When viewing the Fourier transform on a log scale, smaller peaks were being produced of a constant magnitude compared to the main Fourier peaks that incrementally dropped in magnitude. What do these smaller peaks correspond to?

## The Attempt at a Solution

The only thing i can come up with is that the signal was not totally pure? I really don't understand Fourier transforms all that well.

nissanztt90 said:

## Homework Statement

This is a question from a Physics Lab i recently completed. We used a function generator to provide a signal to a spectrum analyzer that performed a Fourier transform on the signal. In this case the signal was a square wave. When viewing the Fourier transform on a log scale, smaller peaks were being produced of a constant magnitude compared to the main Fourier peaks that incrementally dropped in magnitude. What do these smaller peaks correspond to?

## The Attempt at a Solution

The only thing i can come up with is that the signal was not totally pure? I really don't understand Fourier transforms all that well.

Can you post shots of the square wave and the spectrum analyzer screen?

(BTW, I may move this to Intro Physics; I'm not sure yet.)

Cant post a picture unfortunately.

I apologize if its in the wrong forum again, i didnt think Fourier transforms were introductory physics. I ran a search on Fourier and saw mostly advanced physics and calculus and beyond, so i thought this forum was acceptable.

The base frequency was 100mhz, so the standard scale showed increasingly smaller peaks every 100mhz. The log scale showed more or less the same thing with the magnitude of the peaks decreasing but a different scale obviously, as well as peaks that remained at a constant magnitude, maybe 2/3 the magnitude of the largest main peak.

nissanztt90 said:
Cant post a picture unfortunately.

I apologize if its in the wrong forum again, i didnt think Fourier transforms were introductory physics. I ran a search on Fourier and saw mostly advanced physics and calculus and beyond, so i thought this forum was acceptable.

The base frequency was 100mhz, so the standard scale showed increasingly smaller peaks every 100mhz. The log scale showed more or less the same thing with the magnitude of the peaks decreasing but a different scale obviously, as well as peaks that remained at a constant magnitude, maybe 2/3 the magnitude of the largest main peak.

No worries about the forum. Could you maybe sketch the spectrum analyzer display and scan/post it? It's hard to speculate on the source of the other spectrum spikes without seeing their spacing, frequencies, etc.

## 1. What is a square wave?

A square wave is a type of waveform that is characterized by a series of sharp, vertical transitions between two distinct voltage levels. It is commonly used in electronic devices and digital communication systems.

## 2. What is the Fourier transform?

The Fourier transform is a mathematical operation that decomposes a function into its constituent frequencies. It is commonly used in signal processing to analyze and manipulate signals in the frequency domain.

## 3. How is the Fourier transform applied to a square wave?

The Fourier transform is applied to a square wave by first breaking down the waveform into a series of sinusoidal components using trigonometric functions. These components are then analyzed using the Fourier transform to determine their respective amplitudes and frequencies.

## 4. What information can be obtained from the Fourier transform of a square wave?

The Fourier transform of a square wave can provide information about the frequency spectrum of the waveform, including the dominant frequency and any harmonics present. It can also reveal any distortions or noise present in the signal.

## 5. What are some practical applications of the square wave Fourier transform?

The square wave Fourier transform has a wide range of applications in various fields such as digital signal processing, telecommunications, and image processing. It is used for tasks such as signal filtering, noise reduction, and data compression.

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