Questions tagged [doppler]
The doppler tag has no usage guidance.
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Interpretation of Clarke's Doppler power spectral density
What I understand of Doppler spread is that the relative motion between Transmitter (TX) and Receiver (RX) change the exposing time of signal. In rapport to a constant-distance TX-RX, a moving toward ...
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Radar signal processing flow chart
I'm new to Radar in general, and I'm studying RADAR using online resources. I came across the following slide which shows the process flow of the Radar signal processing.
The thing I don't get in ...
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Matched filter loss due to frequency offset
I'm working with a pulsed radar signal which uses linear chirp pulses. I perform pulse compression by applying a matched filter of the simulated chirp waveform and recording the location and power of ...
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How to use a FIR on a signal with a drifting central frequency?
I have been working on this subject for a while and I couldn't get a proper answer.
I am trying to estimate the phase of the input signal :
$x(t)=Ae^{j(at^2+bt+c)}+n(t)+i(t)$
Where $n(t)$ is a ...
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Pulse Doppler Radar: how to filter its Range-Doppler matrix?
I want to simulate a Pulse Doppler Radar with medium pulse repetition frequency (PRF about $100\textrm{ kHz}$, about $500$ pulses in pulse train).
It's rather powerful, and should discriminate ...
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Continuous wave Doppler radar
I am developing a continuous wave Doppler radar to detect human movement at a speed of 0.2-6m/s. For a radiation frequency of 24.15 GHz, the Doppler shift during longitudinal motion will be equal to ~...
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Radar for Vital Signs – Matlab Simulation
Interested to design and simulate FMCW radar for Vital Signs sensing.
The initial signal parameters are(1):
When using the following Matlab code to generate the waveform:
...
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MTI RADAR, DSP algorithm question
Im new to RADAR signal processing.
I using this doc for ref: https://www.mathworks.com/help/phased/examples/ground-clutter-mitigation-with-moving-target-indication-mti-radar.html
I trying to rebuild ...
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Ambiguity function information
For a course that i'm taking im asked a question about the ambiguity function of a FMCW radar. However i have not found a good source for reading about this so don't quite understand it.
I get given ...
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Derivation of Clarke's Doppler power spectral density
I am reading Wireless Communications by Andrea Goldsmith. I have some issues in the derivation of Clarke's Doppler power spectral density given there.
1)For beginning the autocorrelation of the in ...
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How to undo dynamic Doppler effect by software?
I have a signal affected by Doppler effect. In general, the Doppler effect changes the scale of the time and frequency domains. So, to undo this phenomenon, I am using a sampling rate converter. Two ...
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How to interpret an Ambiguity function
I need to evaluate several different waveforms regarding their doppler tolerance, for use in a radar application. So I came across something called the Ambiguity function.
The following picture shows ...
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Does Radio Communication Have to Account for the Doppler Effect?
I know that radio communications take place in specific frequency bands, and that the doppler effect can cause shifts in frequency when there is relative motion between the source and destination ...
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unambiguous velocity $V_\max$ in radar doppler processing
In literature, $V_\max = \lambda\cdot \operatorname{PRF} / 2$; should it be $V_\max = \lambda \cdot \operatorname{PRF} / 4$, which would be consistent with FMCW $V_\max = \lambda / (4 \cdot T_c)$?
...
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Doppler Shifting A Chirp Signal
So I have a digital linear chirp signal:
$$ x[n] = \sqrt{\frac{2}{N}} \cdot \cos\Big( 2 \pi \frac{f_{0}}{f_{s}}n + \pi \frac{B}{N} n^{2}\Big) $$
Where $f_{0}$ is the initial frequency, $f_{s}$ is ...
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FMCW Radar Signal Processing Flowchart / Ambiguity Function
I Read many papers on signal processing for pulsed and FMCW radars, taking the FMCW type, the signal processing start after mixing the received and transmitted signal, the result of this operation is ...
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How does one go about choosing a Radar Cross Section for a human when modelling a Pulse micro-Doppler microwave radar?
So as part of a personal project I'm in the process of simulating and making a fall detector using a 2.7GHz microwave sensor with a range of 8m. I've been using MATLAB's example code to simulate each ...
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Help detecting target in pulsed radar signal
This signal is from the Pasternack $2.4\textrm{ GHz}$ development kit. The saved signal appears to be the pulsed waveform. It is sampled at $20\textrm{ kHz}$ for $4130$ points. I recorded a ...
user19960
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Doppler frequency when down-converting a receiving signal
Suppose we have a monostatic radar system, with only one target crossing at a speed $v$ at the main lobe of the antenna. The Doppler frequency for this case will be given by
$
f_d = \frac{2v}{\lambda}...
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doppler tolerant phase coded waveforms
how do i conclude a waveform shows doppler tolerance, say polyphase code-frank code, without the use of ambiguity diagram? we know that it is doppler tolerant and if we check the frequency spectrum of ...
user70596
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range-doppler map to range-velocity map conversion
UPDATE 2.0
I think I've managed to produce the correct range-velocity map. I'm struggling with analytically calculating the range which I expect to see on the range-velocity map. Could someone please ...
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How to remove the modulation before doing frequency offset estimation?
To use DFT/FFT (or maximum likelihood) method to estimate the frequency offset introduced by the channel, we need to remove the modulation on the received data samples in the front. If the unknown ...
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Doppler Map for a beginner pulsed radar
I have been assigned to simulate a Pulsed radar with Chirps hitting a moving target and then analyzing the data to create a Doppler-Range map.
Im having trouble completing some of the "algorithm'...
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Doppler shift in satellite communication systems
Does someone have a table with doppler shift range for satellite communication systems?
Is it S band or X band?
I have seen somewhere, but I can't find it.
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Fast/Slow Fading: How are doppler shift and coherence time related?
In the literature I've read that fast fading happens if the bit duration is larger than the coherence time of the channel.
The coherence time of a channel is proportional to $\frac{1}{f_{Doppler}}$. ...
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Doppler Shift of Phase Coded Pulse Compression Waveform
Suppose I want to transmit the signal:
$$ x(t) = g\Big(\frac{t-t_{0}}{T}\Big) \cdot \cos(2 \pi f_{0} t + \theta_{0}) + g\Big(\frac{t-t_{1}}{T}\Big) \cdot \cos(2 \pi f_{1}t + \theta_{1}) $$
Where $g(...
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FMCW Radar Doppler Ambiguity related to Nyquist theorem or exceeding the distance frequency or both
I have been reading about doppler ambiguity and I have two explanations for its occurrence that I can't relate to each other.
1st Explanation: In the stationary case (radar and target are stationary) ...
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Range-Doppler Matrix Cells
I am working on developing an understanding on range-gates and the size of each cell. I haven't had much luck in finding information in how the matrix in the image below is generated, so I have some ...
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Motion detection with FMCW radar
I am studying the work of a microwave rangefinder and faced such a problem, but before that, a preface:
I have a microwave module that operates at 24GHz. I use a 1kHz triangle waveform as the ...
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Can velocity be calculated in first stage FFT?
I understand that, For an FMCW radar, the velocity of a target is proportional to the phase changes at same time instants across the chirps.
I have a MxN data cube with N chirps(columns) & M ...
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What is the importance of signal bandwidth in radar systems for velocity and localization estimation
So I know about the basics of doppler shift which relates the velocity of a moving object with the frequency carrier shift seen at the reciever.
But, I don't understand the importance of the ...
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Doppler Shift and the Pulse Repetition Interval
Suppose that I have a signal $x(t)$ consisting of $N$ pulses at a given frequency $\omega_{c}$. I space them $T$ seconds apart, ie the Pulse Repetition Interval (PRI) for the waveform is $T$.
Now ...
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Why do signal have mirror signal after pure frequency shift?
In my Matlab code I have a simple simulation of FPGA with the ability to simulate doppler shift, and after I and Q components plugged into IQmod with some carrier freq.
In my Matlab code when I ...
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FMCW radar IQ data constellation
I am trying to replicate the basic method of vital signal detection based on FMCW radars I found in classical literature on the subject. The issue I am facing at the moment is that of IQ data DC ...
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range-doppler map of FMCW radar
I have created a 2D matrix with L as the number of samples and K as the number of chirps. Now I am trying to plot the Range-Doppler response which doesn't correspond to the correct range and velocity ...
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How to estimate Range, Doppler and Angle with FMCW MIMO Radar?
I am trying to obtain the range, Doppler and angle of arrival estimation with an TDM MIMO FMCW radar.
Actually, I have completed this process. In doing so, however, a few things remained unclear. ...
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Doppler Shift and Wireless Access Points
I am trying to design and implement a system that would calculate the velocity of a hand motion in smartwatch.
The general idea is to calculate the Doppler Shift of each access point and find ...
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How to calculate the doppler shift?
I am writing a QPSK receiver in MATLAB. In the transmitter part, I have generated random data using randi, QPSK modulated and pulse shaped using a RRC filter.
The ...
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In case of using a Doppler radar, do we have to use IQ demodulation to find the direction of a target?
I want to know the way to find the velocity of a target by using a doppler radar.
I read some paper about it,
In summary,
send rf signal to a target
receive the reflected signal from the target.
...
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Use of complex numbers to calculate Doppler effect?
First of all, I'm a beginner in this field, please tell me if any of what I'm asking is too basic / can be found with some google research.
I have a situation with a static TX and a moving RX (v is ...
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Doppler shift in signals
I have started doing some reading into the effects of the doppler shift on signals. In particular, radar signals from ships moving relative to a receiver. This might seem weird but I understand why ...
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Beginner Educational Resources
New member here. Recently got hired into a mid level EE position. Have a BSEE but performed more radar performance analysis at a higher system level previously. In my new group we're doing a lot of ...
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Correcting for Doppler shifts at the speed of sound for a 800 MHz signal
I'm working with a system which is planned to reach velocities of about 340m/s. It's likely that we'll be using a frequency around 800 MHz for rx and tx. At these speeds, supposing a fixed source, the ...
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Range Doppler Graph
The graph includes a peak at zero frequency and some other frequencies. However, my professor says that there should not be a peak at zero. I contend that he is wrong. But my graph is also not right, ...
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How does slow-time FFT detect velocity?
The signal processing steps for a pulsed radar are: Fast time matched filter -> Slow time FFT.
I cannot understand how is the second step able to detect frequency,
because the results after the ...
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Fine frequency correction : grouping and finding max amplitude inside a group
I work on phase and frequency estimation algorithm. Currently I am working on a derivation and determination of the Doppler shift( dF – frequency step).
For each dF, The following algorithm was ...
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Why is fourier analysis used in doppler effect?
I am a high school student that carried out the experiment on the Doppler effect to therefore analyze the graph but after doing some research, I saw one of the articles saying “ Fourier analysis is a ...
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Cant find Doppler shift with LFM signal
Im stuck on this one. I hope someone helps me!
Problem: I need to find Dopler shift with array of reflected chirps.
I have bursts of chirps which then i sampled, and calculated fft.
Im suposed to ...
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Is it possible to detect or localize movement of objects using LPWA (or LPWAN) such as LoRa, DASH7, NB-FI?
Assume that there is a moving human in the room without any device (or receiver). Is it possible to detect or localize movement of objects using LPWA (or LPWAN) such as LoRa, DASH7, NB-FI by analyzing ...
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Frequency Domain Correction of Frequency Offset or Doppler Frequency in LTE
We are working on LTE Uplink CFO Correction for 3 MHz band. The time domain CFO correction is easy, which depends on the processing of 3840 samples step by step multiply by $\exp(-j 2\pi f_\text{...
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