Questions tagged [doppler]
The doppler tag has no usage guidance.
53
questions
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19 views
Generating a 2D delay-Doppler channel matrix
I was wondering if anyone here has any idea on 2D delay-Doppler channel and how to generate the channel matrix?
Even a hint or a resource would be helpful. I just want to understand and visualize the ...
0
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1answer
39 views
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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63 views
Requirement on sampling rate for Doppler shift estimation
What is the requirement of sampling rate on channel impulse response (CIR) for Doppler shift estimation? Suppose that there is a bi-static radar system with perfect synchronization, the receiver ...
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10 views
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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3answers
61 views
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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1answer
58 views
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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30 views
How is sampling rate affect the Doppler spectrum? Textbook attached
I am studying FWGN model, in the textbook "MIMO-OFDM wireless communication with MATLAB", it says "When oversampled by a factor of $N_OS$, the bandwidth of Doppler spectrum becomes \...
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34 views
Correcting large frequency offsets at very low data rates
Consider a typical BPSK system running at a baud rate of 1 kbaud/sec - the receiver needs to deal with severe frequency offsets, let's say up to +/- 1 MHz offset and that the frequency offset can ...
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1answer
51 views
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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1answer
59 views
How to remove frequency offset with RRC as pulse shaping filter
I am working on a project with QPSK modulation format and a RRC filtering at the transmitter (TX) side. The channel introduces a constant dropper shift ($f_d$) to the received signal. To make the ...
0
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1answer
33 views
How to add a frequency offset to a buffer of MPSK signal for simulation purposes?
I need to simulate some channel effect to a buffer of MPSK signal. How to add a frequency offset to a buffer of baseband MPSK signal?
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1answer
75 views
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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1answer
123 views
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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2answers
194 views
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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0answers
52 views
Sound of (sea) waves imitation
I need to create an algorithm for sound of waves. So I imagine it should be a white noise with doppler effect. However I understand doppler is just change of frequency. But white noise have all the ...
0
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1answer
130 views
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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0answers
18 views
Doopler spread and delay spread in an equation of channel freq response
Assumed the transmission system with channel impulse response is determined by the matrices $H(\tau_l) \in C^{N_R \times N_T}$ ( $N_R$ and $N_T$ are numbers of received and transmit antennas)
By ...
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1answer
124 views
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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30 views
frequency domain representation of the doppler shift sequence
This is a bit of a weird question. I have a bunch of IQ data. Its a very big file that i cant upload on here. Im working through a few exercises trying to analyse the data. I have plotted the signal ...
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1answer
90 views
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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1answer
125 views
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 ...
0
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1answer
23 views
A-GPS frequency (fd) search ranges
A-GPS is able to reduce the fd search range from several kHz (GPS search range) to several hundred Hz (a-GPS search range). I know the GPS search range has a center at 0 Hz. What is the center ...
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4answers
58 views
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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1answer
21 views
Converting PLL Discriminator into Doppler error
I'm writing a GPS receiver SDR software, and I have calculated the PLL discriminator ouptut as atan(Q_Prompt,I_Prompt)
I would like to know the formula that converts the discrminator output to doppler ...
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1answer
22 views
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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2answers
182 views
help to calculate phase shift in certain frequency(identified from FFT)
I am designing a 24ghz doppler radar, with 1TX 2RX. Four adc channel are recording at 25khz, applying 256point FFT on adc of both of RX I and Q, I could identify the target in certain doppler ...
3
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1answer
473 views
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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3answers
107 views
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 ...
-1
votes
1answer
119 views
Doppler effect in underwater acoustic channel
I got my BER vs SNR graph as shown. I was trying to show the difference in BER with OFDM signal transmission under Doppler effect and without Doppler effect. However, based on my understanding, the ...
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2answers
244 views
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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0answers
163 views
Range Doppler Maps
I would like to understand from a high point of view how these maps are computed.
On the y-axis we have m/s and in the x-axis the range.
I read something about the Fourier transform etc, but I don't ...
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1answer
262 views
Question about FMCW range-velocity plot
I am working on plotting range-velocity heatmap of the receiving FMCW signal. I actually have already plotted. However, I do not really understand the mapping relationship between Doppler FFT bin and ...
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25 views
DOA estimation of moving, radiating source in the near-field with nonuniform Doppler shifting
I am trying to estimate the DOA of a radiating source using two passive sensors.
In the case of a stationary source, I find the lag $k$ of the maximum in the sample cross-covariance sequence $E \...
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2answers
195 views
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{...
2
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2answers
602 views
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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2answers
171 views
Why having a ridge like Ambiguity Function implies lack of Doppler resolution?
I was wondering why if the AF (Ambiguity Function) has a ridge like form it has low Doppler resolution.
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1answer
40 views
Degrees rotation based on frequency offset?
What is the relationship to calculate degrees of rotation in the constellation given a baud rate and frequency offset?
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1answer
67 views
How to classify the movement type of a target into two categories(direct motion or else) by using a doppler radar?
How to classify the movement type of a target just into two categories(one is direct motion which is almost straight line movement and the other is anything else) by using a doppler radar with a ...
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2answers
1k views
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.
...
1
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1answer
248 views
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(...
3
votes
1answer
97 views
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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1answer
189 views
Measuring Amplitude of sound wave FFT
Please, pardon my ignorance. This may be a simple question, but I am still unable to explain what is happening.
I am using a turtlebot to listen to sound emitted from a stationary sound source.
My ...
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0answers
61 views
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 ...
1
vote
1answer
363 views
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 ...
0
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1answer
1k views
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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0answers
338 views
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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2answers
3k views
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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0answers
222 views
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 ...
8
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2answers
2k views
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 ...
2
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1answer
1k views
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 ...
