AM waveform in frequency domain

In summary, the conversation revolves around sketching the frequency domain for an AM waveform, with a question about the correct labeling of frequencies and the use of peak voltage. The individual asking for help has made an attempt and is seeking confirmation and input from others. There is also some confusion around the use of "k" in the formula.
  • #1
fran1942
80
0
Hello, I need to sketch the frequency domain for the following AM waveform showing total bandwidth and frequency.
8sin(2pi500kt - 4cos(2pi530kt) + 4cos(2pi(470kt)

I have attached an attempt I have made.
Does anyone know if I have this correct or not ?

Thanks kindly for any input.
 

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  • #2
What does that "k" mean in cos(2pi530kt)?
 
  • #3
sorry I don't know what that is referring to. We were not told.

Do you think I have the frequency domain sketch correct based on what we do know?

Thanks for your help.
 
  • #4
Sorry, I can't give an authoritative answer. But I'm wondering whether you might be meant to label the frequencies as 500k, 503k, etc., that k seems to be some scaling factor. Are you sure it's not meant to be x103 and you have changed it to a k?

Also, perhaps someone else can confirm that the vertical axis is okay as the peak value. I'm just wondering whether it should be RMS. Can you refer back to an example in your notes to confirm that peak voltage is what you need to use here? (I've forgotten.) https://www.physicsforums.com/images/icons/icon9.gif [Broken]
 
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  • #5


I can confirm that your sketch of the frequency domain for the given AM waveform is correct. The total bandwidth is shown to be 60 kHz, with the carrier frequency at 500 kHz and the upper and lower sidebands at 530 kHz and 470 kHz, respectively. The amplitude of the sidebands is also correctly represented by the 4cos(2pi530kt) and 4cos(2pi(470kt) terms. Overall, your sketch accurately represents the frequency domain of the given AM waveform. Great job!
 

1. What is AM waveform in frequency domain?

In frequency domain, AM waveform refers to the representation of amplitude modulation (AM) signal in terms of its frequency components. This representation can be visualized as a graph with the frequency on the x-axis and the amplitude of each frequency component on the y-axis.

2. What is the difference between AM waveform in time domain and frequency domain?

In time domain, AM waveform represents the variation of the amplitude of the signal over time. In frequency domain, it represents the signal in terms of its frequency components. The main difference is the way the signal is visualized and analyzed.

3. How is AM waveform in frequency domain calculated?

The AM waveform in frequency domain is calculated using Fourier transform or its variants such as Fast Fourier transform (FFT). These mathematical operations decompose the signal into its frequency components and their respective amplitudes.

4. What information can be obtained from AM waveform in frequency domain?

The AM waveform in frequency domain provides information about the frequency components present in the signal and their corresponding amplitudes. This information can be used to analyze the signal, identify any distortions or noise, and perform filtering or demodulation.

5. Why is AM waveform in frequency domain important in signal processing?

The AM waveform in frequency domain is important in signal processing because it allows for a more detailed analysis of the signal compared to time domain representation. It also enables the application of various signal processing techniques such as filtering, demodulation, and noise reduction.

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