Questions tagged [fft]
FFT is an acronym for Fast Fourier Transform. Use this tag for FFT-related questions. Try to also select a specific chip or software tag when possible.
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What should I make of this spectrum analyzer data?
Here I have two signals that I placed into a spectrum analyzer. Channel 1 (yellow) comes from an avalanche photodiode + TIA circuit that has a 50 Ω output resistor, which is directly connected via BNC ...
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Understanding dBm value of FFT measurements
I am getting familiar with the FFT functionality of my oscilloscope.
I am using a Siglent SDS2204X Plus that has been firmware upgraded to 350 MHz.
Testing of the FFT function involves the use of a ...
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Beat frequency - Square signal
This question comes from this one, LTspice - Beat frequency:
It appears that when I did a FFT of two sinusoidal signals, there was no what is called beat frequency.
When I do the same exercice with ...
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Does the FFT in LTspice not work properly?
I wanted to do an FFT of a square signal in LTspice. Here is the simulation:
Here is the result of the FFT through R4:
There is no reason to have frequencies below 100 kHz according to theory. What ...
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How can I determine how much power is in a frequency range via FFT in LTspice?
When using LTspice, I can see the FFT of a voltage. How can I see how much power is in a particular frequency band, and what portion of the total power it is?
The FFT in LTspice is in dB, but it's ...
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Distinguishing light sources with STM32 ADC and fast fourier transform
I want to identify if there are other light sources present at the same time as a 5 kHz 50% duty cycle PWM LED is on (this is arbitrary and it can be modulated at a different frequency). I have an ...
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Analysis for the peaks in FFT
Suppose I have 2 cases:
1st MOSFET switches with rise times and fall times of around 10ns (Vds).
2nd MOSFET switches with rise times and fall times of around 50ns (Vds).
Both of them have a switching ...
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How can initial switching artifact lift the entire noise floor?
This switching artifacts occur at first data points.
Why does it lift the entire noise floor? Is it because all the frequencies in the white noise got amplitude? or only lower frequencies which is ...
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What to choose for an RF spectrum analyzer A/D conversion
I assigned myself a (long term) project to build an RF spectrum analyzer. In the basis it will be a super or triple (depending on frequency band) heterodyne frontend with digitized IF and some final ...
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Unexpected signal at AD620 module output when Vsupply is on
I bought an AD620 instrumentation amplifier module and below is the module schematic.
Souurce - https://protosupplies.com/product/ad620-instrumentation-amplifier-module/
A problem shows up when I'm ...
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Are these low frequency FFT components due to insufficient op-amp slew rates?
In my circuit I have three op-amps in (direct) series connection:
AD8422 acting as an input buffer (a large input impedance is needed) with a fixed gain (slew rate: 0.8 V/us)
LTC6910 being used as a ...
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Working on 64-point SDF FFT Verilog code [closed]
I am an undergraduate student who has chosen to work on an FPGA project for my capstone. My professor provided me with a PDF file without any context, and now I am trying to figure it out on my own. I ...
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Discrepancy Between Bode Plot Predictions and FFT Output for Higher-Order Low Pass Filters on a 10 kHz Square Wave
I have conducted an experiment where a 10 kHz square wave is input through low pass filters of 1st, 2nd, 3rd, and 4th orders. After passing the square wave through these filters, I observed the FFT (...
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FFT on my oscilloscope is not detecting a peak which is a peak
I am having a strange problem and it's due to that lack of my info about signals.
I examined a PWM output from my MCU under sds1104x-e oscilloscope which is 656KHZ with a duty cycle of around 45.5% ...
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How to plot the FFT in Ltspice?
I'm new in Ltspice and I wonder how to plot the FFT of R1? I just failed to find such a tutorial and I'm sorry for such a stupid question. Thanks for your teaching!
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