Newest Questions
29,025 questions
2
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GNU Radio - Can't sync to QAM16 (messy constellation)
I am trying to do the following experiment. I have HackRF output connected throught an attenuator to RTL-SDR:
HackRF transmits QAM16 modulated signal at 400MHz and on RTL-SDR i want to see a clean ...
2
votes
1
answer
85
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Is the magnitude plot of a general complex function is always even
From the Fourier transform I know that if $x(t)$ is a real function then $$X(j\omega)=X^*(-j\omega)$$ and that $$|X(j\omega)|=|X(-j\omega)|$$ $$\angle{X(j\omega)}=-\angle{X(-j\omega)}$$
My question is ...
- 149
0
votes
1
answer
44
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How does Differential-QPSK help in a non-coherent OFDM case?
I'm trying to build an OFDM modem and ran into the issue of carriers on the Tx and Rx side being close in frequency but very different in phase.
In a single-carrier case, differential modulation ...
1
vote
1
answer
46
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Interpreting EEG spectrogram artifacts: Constant horizontal bands and periodic vertical lines after filtering
I am analyzing EEG data (CHB-MIT Scalp EEG) and generating spectrograms to visualize seizure transitions. I am trying to understand specific artifacts visible in my output to ensure my preprocessing ...
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1
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1
answer
82
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Equivalence between discrete-time and sampled continuous-time systems
This question is motivated by some analysis in section 21.3.2 in the textbook: Analysis and Design of Data Converters by Behzad Razavi.
Suppose I have a discrete differentiator defined by
$$H(z) = 1-z^...
- 359
1
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1
answer
107
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Beats at frequencies near Nyquist frequency divisors and their handling
At a sampling rate of 22050 Hz, if a sine wave signal with a frequency of 11024 Hz (Nyquist frequency minus 1 Hz) is generated in DAW, audible beats (amplitude fluctuations up to the point of the ...
- 111
1
vote
4
answers
295
views
Is it possible to convert a complex IIR filter into real IIR filters?
I created a Hilbert transform filter by frequency shifting a low-pass IIR filter:
...
- 346
1
vote
2
answers
163
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simulation for a frequency-flat fading channel
I would like your opinion on the simulation for a frequency-flat fading channel in Matlab. I use:
h=randn(1,1)+1i*randn(1,1);
r=abs(h)*s;
where $s$ is the ...
- 11
2
votes
1
answer
104
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Is the common definition of the Markov Property as "memoryless" mathematically loose?
I am trying to reconcile the definition of the Markov Property with the rigorous definition of statistical independence, specifically in the context of continuous-time systems (like Flow Matching or ...
- 141
0
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0
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38
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Very small acceleration data from IMU
I'm trying to process acceleration data from an MTw IMU installed on a person as it moves. The idea is to detect heart beat and similar data.
I noticed that while resting, I'm able to detect it but as ...
- 111
0
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0
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44
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Computing process noise for a Kalman filter, with know measurement noise
I am working on a Kalman filter with measurement vectors $\{x_i\}$, and I have a reliable way of computing the measurement noise variance matrix. For the process noise, I would like to use the ...
0
votes
1
answer
75
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finding whether a signal is Wide-band or Narrow-band using deviation ratio
I have an FM modulator that is followed by a bandpass filter having a center frequency of 1000 and a bandwidth of 70 Hz.
When applying FM modulation the unmodulated carrier has a frequency of 1000 Hz ...
3
votes
1
answer
177
views
Brownian noise vs. random walk
I have a basic confusion about random walks. I have seen three things:
Brownian noise describes random walks (here and here).
Brownian noise is stationary (here and here and here).
The variance of ...
- 131
0
votes
1
answer
120
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Instantaneous amplitude of audio using the Hilbert transform
A question was asked here 12 years ago and the answers don't seem to correlate with what I am seeing in experimentation.
I am creating an audio spectrum analyzer, and I am currently squaring the ...
- 346
1
vote
2
answers
107
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determining periodicity of a respiratory signal
I would like to know the suggested route for determining how periodic a respiration signal is using signal processing. I know the sampling rate, and the N-length is different for each trace, however I ...
