Questions tagged [radar]
Anything related to RADAR (RAdio Detection And Ranging) systems and radar signal processing.
111
questions
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22 views
FMCW Radar using FSK Superimposed LFM ramp
While reading the datasheet of the ADF4159 I came upon a section describing how to create an FMCW ramp with FSK superimposed to "enable unambiguous (distance and velocity) multitarget detection&...
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1answer
58 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 ...
1
vote
1answer
94 views
Generating IF signal for FMCW radar
I am trying to generate a signal that represents mixer output of FMCW radar. I am using MATLAB and already tried out this tutorial. There, Phased Array System Toolbox is used to showcase how FMCW ...
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0answers
20 views
How to calculate FMCW Radar Chirp STFT?
I have received signal from FMCW Radar which is of the shape [128x64] = [Number of samples per chirp x Number of chirps per cycle] and i want to calculate the stft
i am calculating it with stft ...
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0answers
11 views
Advantage of “multi-static” transceiver configuration
Assume I have a system with one mobile station and multiple Transceivers (similar as in a "multi-static" RADAR system), in this example 4 transceivers:
The bit error rate from RTX $i$ to the mobile ...
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0answers
19 views
Noise level estimation using Hildebrand & Sekhon method
I have some data from a radar to process in order to find the moments and in turn the wind speeds. I have no prior knowledge in signal processing so it's giving me a hard time to estimate the noise ...
0
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1answer
33 views
Why does my I/Q data from radar are not centered?
I am working on the IQ raw data from FMCW radar. I plot the I and Q data, they seem to be strongly shifted from the center. And the amplitude of I and Q also varies. I don't understand why it looks ...
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0answers
40 views
Does a time varying gain (AGC) mitigate clutter in radar signals?
Trying to implement an MTI filter for flatland clutter in a radar received pulses.
However, after the matched filter output instead of implementing directly the MTI filter, I normalized with an ...
0
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1answer
78 views
DSP based FMCW radar
I have an SDR receiver I'm interested in making into a FMCW radar. The bandwidth is somewhat narrow as it only samples at 64 MSPS.
There is a problem in that without a bunch of embedded programming ...
1
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4answers
35 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}...
0
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1answer
41 views
FMCW radar: Linear phase change determination with sinusoidal decomposition
I am struggling to understand how linear phase shift can be determined with a transform whose main purpose is to determine frequencies rather than rate of change of a function.
In FMCW radar, ...
1
vote
1answer
48 views
Is it fast time or slow time for the delay in the ambiguity function domain for radar signal?
I am confused about the delay concept in the ambiguity function. The FFT of slow time is the doppler frequency. However, people usually relate the range-doppler domain with the ambiguity function ...
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2answers
46 views
Coherent detection in radar and radio signals
Coherent demodulation\detection is usually done via matched filtering in RF signal processing. In radar signals, coherent integration can be done if the phases of the returns are known. In terms of ...
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1answer
20 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 ...
1
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0answers
40 views
Sign of manifold vectors in monostatic phased-array radar
I am reading some notes where the impulse response of phased-array to is given by;
$$
\beta S(\theta, \phi) \bar{S}^H(\theta, \phi) \cdot \delta(t-\tau)
$$
where
\begin{align}
\bar{S}(\theta, \phi)...
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0answers
30 views
Block Processing to Plot Phase in Real Time
I am trying to modify an LTFAT demo script that records and plays back streaming audio simultaneously. The objective is to read in the block to a vector, and take the DFT of the block samples, and ...
0
votes
0answers
81 views
Identify an obstacle in front of the radar
I use the K-LC6 24 GHz microwave module in the linear frequency-modulated signal mode to determine the distance to moving objects. But if I put a barrier in front of this radar while it is moving, I ...
0
votes
1answer
52 views
Digital beamforming and phase shift stage insertion
I have read some literatures about the different topologies of beamforming and it came to my mind a question : where is applied the phase shift for each channel depending on the type of topology/...
0
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1answer
48 views
Is it possible to observe more area in azimuth than physically traveled in stripmap SAR?
I have been examining stripmap SAR algorithms, mainly Range Migration Algorithm. When I check the textbook examples so far I always saw the data trajectory is larger than scene that is observed. An ...
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0answers
16 views
Detect number of targets from the FMCW data matrix
Currently, I already have an FMCW data matrix which was acquired by the SISO radar. Based on this data matrix, I want to estimate number of targets in it. And then I can apply some blind source ...
0
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0answers
92 views
Stolt interpolation and ifft in range migration algorithm
I am using range migration algorithm for focusing stripmap synthetic aperture radar data. I have successfully tested my algorithm using the following steps after range compression (similar to this ...
0
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0answers
31 views
Motion compensation for stripmap SAR
I am trying to perform motion compensation for an airborne stripmap SAR data following the book Synthetic Aperture Radar Processing by Franceschetti and Lanari. The algorithm flowchart is on page 145. ...
0
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1answer
59 views
Range Compression
How exactly is the SAR image resolution increased by the linear frequency modulation of the transmitted signal and further by the compression of range and azimuth?
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3answers
96 views
3D model from high speed videos?
Is there a way to convert or somewhat replicate RADAR data from a set of given high speed videos taken from multiple angles.
The problem is quite ill defined but the task I have in hand is to ...
0
votes
1answer
61 views
How to perform dechirping of SAR image in MATLAB?
I have the transmitted pulse and the raw SAR image before range compression (dechirping). I understand the pulse compression its a convolution along the columns but I am not able to make it work. I've ...
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1answer
96 views
Synthetic Aperture Radar (SAR). How to do Range Compression?
I am trying to perform range compression to a raw SAR image [fast times, sensor position], Dr in code. I have the transmitted signal (chirp), g in code, and literature says range compression is ...
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0answers
23 views
modelling radar system for image generation
I am trying to find or derive some model for radar using python and blender which should hopefully create a simulation of what a radar image of the blender environment would look like.
I have been ...
3
votes
1answer
162 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 ...
2
votes
2answers
99 views
Pulse Doppler Radar: time delay in down conversion
My understanding of Pulse Doppler Radar is the system measures Time Of Flight for the pulse.
My confusion is that during the down conversion process prior to ADC the lowpass filter causes some time ...
-1
votes
1answer
51 views
Coherent Radar — How do we justify it?
How can we justify doing coherent radar when the phase of the return is unknown?
For instance, after a reflection, assuming a stationary target, we should get something akin to:
$$ x_{rx}(t) = |\...
2
votes
1answer
45 views
Minimizing Time Sidelobes with Pulse Compression
I am trying to compute a compression filter function to minimize the error from a a desired pulse compression result.
The usual approach to doing this is to minimize the RMS error of the the ...
3
votes
1answer
134 views
FFT strong signal in middle frequency bin
I've developed a radar that I'm using to determine the distance to remote objects. It uses a custom PCB with an onboard FPGA that performs the DSP algorithms. The data from it is then plotted on a ...
0
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0answers
43 views
Range Migration Algorithm in FMCW MIMO radar
I’m using a FMCW MIMO radar [77-79 GHz] with a virtual linear array made of 48 channels.
I’m wondering if the adaptation of the range migration algorithm (typically used in SAR processing) is ...
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0answers
33 views
MIMO FMCW radar - back-projection
any suggestion how to start implementing the back-projection algorithm in a FMCW MIMO radar? Currently I'm using 2D FFT to get radar image, I would try time-domain algorithms to improve the overall ...
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0answers
77 views
Root MUSIC and solution of conjugate palindromic polynomials
The root-MUSIC algorithm gives direction of arrival angles directly and avoids the computational overhead of computing the MUSIC estimator curve (see Direction of Arrival Estimation using a Root-MUSIC ...
0
votes
1answer
51 views
How is ESPRIT pronounced?
I'm implementing high resolution DOA algorithms including ESPRIT for radar systems. The word ESPRIT is obviously an acronym but, even so, how is it pronounced? Is the second i long like "ESPREEE" as ...
2
votes
0answers
54 views
Combining two images with different resolutions?
I am attempting to combine two radar images, each of which is a 3-dimensional cube with a range dimension, an azimuth angle dimension, and an elevation angle dimension. One image has high azimuth ...
1
vote
2answers
154 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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votes
1answer
212 views
Advantages and disadvantages in term of radar performance of LFM chirp
Which are the advantages and disadvantages of a LFM chirp regarding its radar performance?
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0answers
26 views
How to create test vectors for wideband beamforming aplications?
I'm trying to create test vectors for a beamforming algorithm I'm simulating in Matlab. I have a complex signal and I want to create the signal as seen by each antenna element. This will allow me to ...
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0answers
26 views
Zero delay cut of LFM complex chirp
I am computing the zero delay cut of the ambiguity function a LFM chirp:
$\chi(\tau = 0, \nu) = \int_{-\infty}^{\infty} u(t) u^{*}(t)e^{j 2 \pi \nu t} dt = \int_{-\infty}^{\infty} A e^{j(2 \pi f_0 t + ...
1
vote
2answers
59 views
Matched Filters for attenuation detection?
I have been reading about matched filters and I'm interested in possible uses for them,
I have seen they are used very often in radar, in such a way that you send out a signal, and then you read the ...
0
votes
0answers
30 views
Why the ideal ambiguity function (AF) for radar has the maximum in (0, 0) and zero otherwise?
I was wondering why is the ideal AF has zero value in all the function except in (0, 0).
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votes
0answers
36 views
RRC filter or rectangular pulse shaping filter in LFM chirp signal
I am working with a LFM up chirp signal, and I wanted to embed some data on it using a BPSK constellation. My doubt was, ¿should I use a RRC filter, like in usual communications schemes, or should I ...
0
votes
1answer
148 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 ...
0
votes
1answer
162 views
Real signal from I,Q, sample rate and center frequency
I am given a recording of an ionosonde sounding. The signal $S$ is represented as a series of I/Q pairs at a sample rate $F_{sr} = 10\,\text{MHz}$. I am told that the center frequency of the ...
0
votes
1answer
340 views
Baseband representation of a LFM chirp signal
I need to generate a chirp signal between $f_{start} = -f_{limit}$ and $f_{stop} = f_{limit}$, to compare it to a FrFT generated signal.
The FrFT signal of order $\alpha = 0$ is PAM modulated data ...
0
votes
2answers
554 views
Omega-K algorithm implementation for synthetic aperture radar
I have been trying to develop Omega-k algorithm for SAR image formation. I am using the equations from chapter 8 in digital processing of Synthetic Aperture Radar data by Cumming and Wong. The steps I ...
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0answers
52 views
Precision accuracy radar
in radar systems how does one measure the precision and accuracy on a radar?
I'm confused with differen definitions in the references:
Richards define (Principles of Modern Radar: Basic Principles - ...
1
vote
1answer
116 views
Carrier frequency of chirp signal
I am computing the link budget for a communication-radar (CoRadar) system. The formula for maximum distance, in communication, is:
$d_{max} = \sqrt{\frac{P_t}{\tau}\frac{G_t G_{r, comm} \lambda^2}{(4\...
