Questions tagged [radar]
Anything related to RADAR (RAdio Detection And Ranging) systems and radar signal processing.
92
questions
2
votes
2answers
48 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
40 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) = |\...
1
vote
1answer
34 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
103 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
votes
0answers
27 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 ...
0
votes
0answers
21 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 ...
1
vote
0answers
69 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
48 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
37 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
75 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 ...
0
votes
1answer
79 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?
0
votes
0answers
22 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 ...
0
votes
0answers
23 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
53 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
23 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).
0
votes
0answers
30 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
0answers
68 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
0answers
30 views
Automotive Radar Simulation
I am looking to simulate a radar channel and a waveform to test some ideas from other signal processing domains on automotive radar.
However, I have no experience with the typical automotive radar ...
0
votes
0answers
63 views
FMCW radar beat resolution with target spectral width, non-linearity and receiver resolution
The question is about resolution of FMCW radars whcich send triangular frequency waveform, receive it's echo then mix it with sent signal, extract beat frequency. The beat frequency is proportional to ...
0
votes
1answer
101 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
0answers
48 views
Doppler shift in police radar
I don't understand how the radar frequency can be extracted from this diagram :
(source:https://copradar.com/rdrparts/)
and specially i don't understand what is the role of PLL and IF circuits and ...
0
votes
1answer
153 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
1answer
270 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 ...
0
votes
0answers
68 views
range resolution FMCW radar influenced by Nyquist?
I am puzzled about this for some time now. According to theory, the max range of a FMCW radar in practice is limited by the sampling frequency
$R_{max} = \frac{c_0 T_{upchirp}}{2 f_{BM}}f_s$
Since ...
0
votes
0answers
37 views
How to find the filter coefficient of matched filter to detect the pulse of a signal?
I would to understand how to find the coefficient of a matched filter.
Let's consider we have a signal and the signal is buried in the following noise. we want to find the coefficient of a matched ...
0
votes
0answers
14 views
Age of information and measurement rate typical for automotive radar devices
I'm working on an automotive application which uses radar information and I need to create a basic model of the radar to simulate its behaviour. I need to know 2 parameters:
-Measurement rate: With ...
1
vote
0answers
34 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
79 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\...
0
votes
0answers
26 views
FM/CW NOISE RADAR
I am trying to generate the white noise signal which I want to modulate using the sinusoidal wave for the radar-target application. I used fmmod() but I am confused is this right choice. I came across ...
0
votes
2answers
93 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.
0
votes
0answers
46 views
Radar - CFAR processing post Digital Beamforming - efficient alternative methods
A radar using a ULA with a large number of elements(for instance N=150 for 1[deg] beamwidth[1]) is being designed.
After the Range and Doppler processing, Digital Beamforing is being performed, ...
0
votes
1answer
22 views
how can I plot a power spectrum for 150 range bins with 512 fft points [closed]
This is my code for plotting... However when I plot my spectrum data using this code, it is showing only 1 row. How can I plot all 150 rows? Can anyone help me to solve this?
...
0
votes
1answer
58 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 ...
0
votes
2answers
445 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.
...
0
votes
1answer
109 views
References ISAR - Inverse Synthetic Aperture Radar [closed]
Anybody know a reference to start understanding ISAR? Book or article.
Thanks!
0
votes
0answers
43 views
Space-time filtering vs. beamforming
Say I have a dense linear array of sensors in space and an acoustic signal propagating through them.
In this case, how would delay-and-sum beamforming compare to space-time filtering by masking the ...
1
vote
1answer
142 views
Light Detection and Ranging (LIDAR) Range Bias Compensation with Light Dependent Resistor (LDR)
I have a distance sensor (VL53L0X), which measures the distance to an object. It is placed outside. I currently do 100 measurements in the best available range mode, then I take the median and insert ...
0
votes
0answers
397 views
FMCW radar 3D FFT for DOA estimation
I'm dealing with transformation of coordinates after I do the 3d FFT doa estimation.
Data below is a car in front of the radar board, and the angle of arrival is "0", 50m.
Left image is the row has ...
1
vote
1answer
167 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(...
2
votes
1answer
815 views
How to Calculate the Ambiguity Function
(Maybe this should be on Stackoverflow instead ...)
What is the best way to calculate the ambiguity function? There are different implementations out there for Python (like PyTFTB or from ...
3
votes
1answer
73 views
motion compensation for range migration algorithm
Is there a simple to follow explanation of how to do second order motion compensation for range migration algorithm?
The one described in Carrara et al is for the ideal case. For the Extended Omega K ...
1
vote
1answer
218 views
CFAR detectors and interference
Constant False Alarm Rate (CFAR) is an automatic thresholding technique. It's situated after the FFT processing in other to detect target peak. This probability of detection depends on clutter and ...
1
vote
0answers
78 views
Is there a situation when maximizing SNR doesn't also maximize probability of detection?
The problem I'm working on is signal detection of a radar signal, but I suspect this problem shows up in many different branches of signal processing.
Background:
From [1], the factor $I_f$, by ...
-1
votes
1answer
395 views
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 ...
0
votes
1answer
267 views
Radar video signal and matched filtering
In order to make my question more clear and give more details
I'm trying to understand the processing signal procedure in radars,i understood till this moment that a transmitter generates a signal ...
0
votes
2answers
2k views
Deriving the resolution equation of an FMCW radar
I am interested in the equation that depicts the resolution of an FMCW radar. I write the same below.
$\Delta d = \frac{c}{2b}$
First I would like to have an intuitive explanation to the above ...
2
votes
2answers
106 views
Compressive sensing and sparsity
We apply compressive sensing to reconstruct a signal if it is sparse in the original domain or has a sparse represetation in some basis.
How we may know a if a signal is sparse or has a sparse ...
0
votes
2answers
303 views
DOA - 1D Music Algorithm
I am currently working on a MUSIC algorithm for DOA of RF emitters in 3D.
At the first stage, interested to apply the 1D MUSIC using a linear array of 4 antennas, and estimate only the azimuth of the ...
0
votes
0answers
144 views
Spectrum of received signal from radar fm-cw
I obtained actual data from a researcher, consisting of a matrix composed of several received signals from an up-ramp fm-cw radar.
Wouldn't be reasonable to plot the spectrogram of a ramp up and ...
0
votes
1answer
72 views
azimuth extent for range migration algorithm
Is it true that in the Range Migration Algorithm for synthetic aperture radar, the azimuth extent can be said to span the length of the flight path?
This makes sense but also does not make sense. ...
