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Is it possible to reconstruct the continuous frequency spectra from DFT/FFT?

Given the output of some FFT (lets call it X) with N bins (lets say 2048) is it possible to recover the values in between the bins in the same way that I can recover the values in between samples of a ...
little_brindle_dog's user avatar
0 votes
1 answer
16 views

White noise vs low-pass filters

It seems common that people assume white (aka Gaussian) additive noise. Yet it is also common to use low-pass filters to remove noise. But white noise shows up equally on all frequency bands. So it ...
profPlum's user avatar
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0 answers
8 views

Pixel Shift when using Fourier Interpolation

I am working on a Super-Resolution network, and want to try to use Fourier interpolation, different from the normally used bicubic interpolation as it relates to MRI imaging. I have tried using this ...
Christoffer Overgaard's user avatar
0 votes
0 answers
13 views

Audio delay with feedback

I'm writing a simple "audio delay effect", with feedback (the closer FEEDBACK from 1, the more the repetitions ...
logijaz's user avatar
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1 answer
20 views

What's wrong with 180 degree phase shift in QPSK?

I red that 180 degree phase shift causes spurious high frequency components which As a result methods such as OQPSK are invented, but I can't understand how it can happens? In fact, I can't find any ...
Ang's user avatar
  • 25
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0 answers
13 views

How to correctly visualize GFSK traffic in GNU Radio

I acquired some GFSK traffic from 2.4 GHz with HackRF at 20 MSPS. I want to visualize the raw bits after quadrature demod (as shown here). Only visualize, I don't need exact decoding. However, the ...
filo's user avatar
  • 125
0 votes
2 answers
53 views

Recover high pass filtered square wave

I'm designing UHF RFID receiver. My receiver has high pass filter and I would like to recover original square wave and then use matched filter. My high pass filter is in hardware and it is difficult ...
rf-engineer's user avatar
0 votes
1 answer
22 views

Radar Signal Modelling based on Channel Estimation

I am a newcomer to digital signal processing. Recently, I have been interested in this question: If we model a reflected radar signal from a target as $$y(t)=h \ast x(t) + n(t),$$ where $h$ is a ...
Rayzain's user avatar
  • 23
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1 answer
40 views

Are there modulation schemes that use more bandwith than they need to, but don't require a spread-spectrum code to decode? (besides AM)

In this answer to Have deep-space spacecraft always used some form of spread-spectrum for data downlink? space scientist Mark Adler explains that while spread-spectrum proper (using specific codes in ...
uhoh's user avatar
  • 231
1 vote
2 answers
69 views

Excel FFT of Two Sine Waves Not Giving Expected Results

I did an FFT in Excel on a 440 Hz time domain sine wave, $y_1(t) = \sin(2\pi\cdot440\cdot t)$, and got the expected output in the frequency domain: a single-spike distribution with 100% of the signal ...
Data2Dollars's user avatar
1 vote
1 answer
14 views

Determining system clock frequency for a given sampling rate and number of channels

I am designing a multielectrode application on fpga. I am recording from multiple electrodes at a sampling rate of 2KHz. Lets say I want to create 60 channels for reading from 60 electrodes. My ...
GGChe's user avatar
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0 answers
9 views

What is Roboflow doing for its "exposure augmentation"?

I was able to find a small blurb here that describes what Roboflows exposure augmentation does. I'll reproduce the text here for convenience: Adjust the gamma exposure of an image to be brighter or ...
user20672's user avatar
  • 101
0 votes
1 answer
38 views

FFT2 to RFFT2 Fourier plane and similarities

I'm trying to understand how Python's fft2 is different from irfft2. Basically, I have some continuous Fourier 2D samples that I need to put in a (n,n) grid (this can be done by a simply count-in-cell ...
Miguel Cárcamo's user avatar
0 votes
1 answer
34 views

Implementing an SDR using C++

coming from an embedded background, i'm not that familiar with DSP/SDR and there's project i'm working on, i have been working with gnuradio and things are working fine, now i'm looking for a try to ...
Oussama's user avatar
0 votes
1 answer
43 views

Is the magnitude spectrum of the Discrete Time Fourier Series of a Discrete Time periodic Signal , an even Function?

We know that the magnitude spectrum of a continuous time fourier series representation of a real periodic signal is an even function (i.e. symmetric about y axis). Does this hold true for discrete ...
amoghfyi's user avatar
1 vote
0 answers
45 views

Proof that the order of a linear prediction model cannot be reduced by analysing non-adjacent points

I have a signal, for which a linear prediction model of order $M$ can be constructed. This means, that a system of the shape $$ \begin{bmatrix} s_0 & s_1 & \cdots & s_M \\ s_1 & s_2 &...
Tigozawr's user avatar
2 votes
2 answers
183 views

Differences in PSD for windowed vs non-windowed spectra

For a non-windowed spectrum, this article gives this equation for the power spectrum $$\text{PS}(k)=\frac{1}{N^2}|X(k)|^2$$ and this for the power spectrum density $$\text{PSD}(k)=\frac{N}{f_s}\text{...
Daniel Somerville Roberts's user avatar
0 votes
1 answer
27 views

How to make frequency histogram from raw measurements?

I have a quadcopter with some motors. I'd like to run the motors at different speeds and analyze the different frequencies of the chassis vibration. A gyroscope+accelerometer in the center, measures ...
CaptainCodeman's user avatar
1 vote
0 answers
37 views

Discussion on the relationship between the FFT magnitude spectrum and the corresponding actual amplitude

This might be a bit long, but it's a question that has troubled me for a long time, and I hope to get everyone's help. When studying signals and systems, we usually only pay attention to the relative ...
lilili's user avatar
  • 11
9 votes
3 answers
1k views

Why doesnt DFT Padding cause sinc like features

I'm new to the land of DSP so any incorrect terms please let me know. It seems padding the time domain signal can make the magnitude spectrum look 'nicer', the fact it doesn't gain any more useful ...
George kirby's user avatar
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0 answers
11 views

Down-scaling image at each step in LoG blob detection

I'm new to CV. I'm currently implementing the LoG blob detection. I've come across this repo on Github: BlobDetector. The main implementation is here: Blob. I'm confused by the down-scaling of image ...
Ak1's user avatar
  • 1
0 votes
0 answers
13 views

Why is my target showing up with a non-zero centered velocity? I captured this data using the IWR6843A0P using a stationary corner reflector

I need help understanding what I should do to determine why my target is showing up in my Range doppler map with a non-zero centered velocity when I captured my measurement using a stationary corner ...
level2fast's user avatar
0 votes
2 answers
57 views

Jitter model does not behave as expected after FFT

So I'm currently trying to understand the relationship between jitter and phase noise. To help my understanding I did write a little simulation in matlab. I used this model in the time domain, relying ...
Maci's user avatar
  • 1
0 votes
0 answers
38 views

Wireless Communication: detecting if a bit 0 changed to 1

I am new in wireless communication, and now I have a 0/1 string like 0010000 (only one bit 1) and wanna send it to the receiver wirelessly. Am I able to detect if the receiver get this string ...
yao zhao's user avatar
1 vote
0 answers
25 views

Python: tune Least Squares Support Vector Machine (LS-SVM) With Gride Search Optimization

Iam looking for LSSVM with GrideSearch optimization in python, but could not find it. Scikit learn has SVM with Gride search but not for LSSVM. Please could you help Thank you
novin's user avatar
  • 11
0 votes
0 answers
13 views

Real-world examples of unweighted directed graphs

Social Networks, Internet Traffic, Citation Networks, Transportation Networks, and Biological Networks exemplify real-world instances of unweighted directed graphs. Within these domains, the Graph ...
ABB's user avatar
  • 367
0 votes
2 answers
62 views

Peak FFT Frequency Off By One Bin

I used Excel's FFT feature to compute an FFT of a 440Hz sine wave that I also generated with Excel. The peak FFT value should occur at 440 Hz. Instead, it occurred one bin later at 528 Hz, so I'm ...
Data2Dollars's user avatar
0 votes
0 answers
11 views

Matching closed form BER with integrals for QPSK modulation

I am trying numerically compute the $\bar{P}_b$ for QPSK in a Rayleigh fading channel according to the formula, $$ \bar{P}_b = \int_0^\infty P_b(\gamma)p_{\gamma_s}(\gamma)\ d\gamma $$ for QPSK $P_b(\...
albusSimba's user avatar
2 votes
1 answer
39 views

Finding the right phase offsets for minimizing the highest absolute value of a sum of sinusoids

suppose I have a sum of cosine waves. Their frequencies are 500 Hz, 501 Hz, 502 Hz and so on, all the way up to 900 Hz. The important thing here is that the amplitude of the slowest one and of the ...
Petr's user avatar
  • 23
0 votes
1 answer
72 views

What's Nyquist frequency in DFT?

I'm currently studying digital signal processing at university but I can't figure out what the Nyquist frequency means in the DFT coefficients, I know what the Nyquist frequency is in the sampling ...
minghierid's user avatar
1 vote
2 answers
121 views

Can modern CPU architectures exploit FIR symmetry

It's been a while since I've read on computer architecture. But I remember my CPU classes where we looked at the Harvard architecture. So basically it got me wondering whether or we can actually make ...
Ben's user avatar
  • 3,777
0 votes
0 answers
42 views

Possible to combine and/or compare a swept Sine and a wide band noise signal?

I am working on a problem where two profiles need to be compared. One is a swept sine in $m/s^2$ (Acceleration) and the other is a sine-on-random signal composed of a swept sine $m/s^2$ and a random ...
SpillTheFFTea's user avatar
1 vote
0 answers
41 views

BER of coherently detected DBPSK?

I understand that differential PSK is generally used when coherent detection is not possible, and so is usually detected non-coherently. However, for sake of theoretical analysis/understanding, what ...
syeh_106's user avatar
  • 213
1 vote
0 answers
10 views

Suggestions for image region separation

I have some SEM images that I need to process,all those images have extra information in the bottom of the images as can be seen in the red bounding box. I need to remove those portion before doing ...
mohammad's user avatar
0 votes
1 answer
36 views

What measures are used to identify a faulty speaker?

I'm working on building a mobile app that would play a sound via speaker, record itself and process this recording to identify faults within speakers, what meastures or parameters should be considered ...
Priyank Joshi's user avatar
0 votes
0 answers
31 views

Comparing custom Welch periodogram with Julia's Welch periodogram

I wrote my own PSD struct in Julia for practice purposes. It involves two type of constructors: a "direct" PSD and a <...
lafinur's user avatar
  • 135
0 votes
1 answer
28 views

Can a bad quality sound be measured via THD?

I'm trying to create an app that measures the audio quality, this is ideally to filter out blown out or cracking speaker who has different types of distortions, what would be the best measurement ...
Priyank Joshi's user avatar
0 votes
0 answers
15 views

Detecting a large horizontal band in the center of an image

I have a small (228x228) grayscale image that I have created by segmenting the original image and converting it to grayscale after applying colors to the segment. I want to know possible approaches I ...
requiemman's user avatar
0 votes
0 answers
9 views

Derive white balance matrix operator in YUV space

Assume that the white balance matrix operator in RGB space is $$W=\begin{bmatrix} \alpha &0 &0 \\ 0 & \beta & 0 \\ 0&0&\gamma \end{bmatrix}$$ where the constants ...
In the blind's user avatar
0 votes
1 answer
35 views

BPSK decoding with a non-ideal transmission medium

I'm simulating tranmission via power line communications (PLC) using BPSK. Due to the coupling circuit and slightly inductive nature of the line, the BPSK signal received is far from ideal. In the ...
mr_js's user avatar
  • 101
0 votes
0 answers
43 views

Is it possible to cheaply convert analog to digital at the gigahertz sampling rate?

Consumer software-defined radio devices have become much cheaper and offer sample rates in the tens of million samples per second, but that still seems too low to parse WiFi or ethernet in-software. ...
Zaz's user avatar
  • 101
2 votes
0 answers
37 views

Baseline correction for XRD data in Origin

I have been trying to process the XRD data for a material, in Origin. I am an undergrad, new to the software, and while I have learnt to perhaps plot the data, I am not able to perform baseline ...
Sevfeynn's user avatar
0 votes
1 answer
131 views

How to find frequency , location and phase of two sinusoid signal buried in noise?

There is a data set which has two different sinusoids buried in noise. Data record has following properties: A data records with a total data length of 2048 points. The sampling frequency is 100 Hz. ...
Thouhidul Islam's user avatar
1 vote
1 answer
65 views

What factors could affect the scale of PSD estimation?

I was required to program a function in R to estimate power spectral density of EEG data. The function I created is, I think, rather standard, and estimates the PSD of a signal by computing $$ \frac{2|...
lafinur's user avatar
  • 135
1 vote
1 answer
45 views

Ignoring Negative Frequencies from FFT on Real Time Series Seems Inconsistent With Time Series

I ran an FFT on real financial monthly time series data. If I plot the FFT frequency domain output on the interval $[0, f_s)$, the dominant frequency pair peaks occur at $f_{A1}$ $\approx$ $0.02 \ ...
Data2Dollars's user avatar
1 vote
1 answer
55 views

Question about reducing phase delay in filters for microcontroller application

I am trying to design a filter to smooth out some of my sensor data. This is for a control systems application where I have limited phase margin. I am looking for a solution where I can maintain lower ...
Mr Phase Locked Loop's user avatar
0 votes
0 answers
37 views

Related to SNR in wireless communication

I am working on a research paper related to wireless communication, wherein I am facing some doubt while writing expression of SNR (which is a ratio of Signal variance in numerator to Noise variance ...
Pranu's user avatar
  • 3
2 votes
0 answers
59 views

Smoothing Filter on Signal

With python scipy I am processing (in real time) chunks of 250,000 each a CW pulsed beep radio signal in python from a RTLSDR. The signal after some basic processing and decimation is 9995 samples ...
Al Grant's user avatar
  • 121
0 votes
0 answers
27 views

Equalizing Standard Deviations of Sequences through Smoothing

I have several sequences with varying standard deviations, and I want to smooth them so that each sequence has approximately the same standard deviation, which I've predetermined. I'm open to any ...
Vlad's user avatar
  • 225
0 votes
1 answer
46 views

Regarding SINR (Signal to Interference Plus Noise Ratio) in wireless communication

I am working on a research paper related to wireless communication, wherein I am facing some doubt while writing expression of SINR (which is a ratio of Signal variance in numerator to Interference ...
Pranu's user avatar
  • 3

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