Questions tagged [radar]

Anything related to RADAR (RAdio Detection And Ranging) systems and radar signal processing.

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120 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 ...
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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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2answers
2k views

How to calculate resolution of radar?

I am working of FMCW radar. Below are all the parameters of FMCW radar. How can I Calculate the resolution of my radar ...
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1answer
673 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
301 views

Should the transmitted signal be continuous in FMCW?

I am a novice in this field and working on respiration detection through near ultra-sound between $18 \textrm{kHz}$ and $20 \textrm{kHz}$. In the referece article and other radar use articles, the ...
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2answers
99 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
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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1answer
316 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 ...
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2answers
4k 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 ...
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1answer
544 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 ...
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2answers
145 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 ...
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0answers
46 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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87 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 ...
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1answer
61 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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3answers
99 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 ...
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0answers
306 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 ...
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1answer
263 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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1answer
103 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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46 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. ...
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2answers
110 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 ...
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1answer
2k views

Radar SNR for a LFM Waveform

How do you estimate the detection SNR for a radar transmitting an LFM (chirp) waveform? I'm looking for an SNR equation that is a function of chirp bandwidth and compressed (or uncompressed) ...
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0answers
32 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
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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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1answer
169 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 ...
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2answers
145 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 ...
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1answer
73 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) = |\...
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1answer
72 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 ...
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0answers
187 views

How to remove echo/reflected-sound caused by stationary objects when building a ultrasound based radar

I am emitting ultrasound with a speaker and am trying to track moving objects with a microphone array by detecting doppler shifts. I have succeeded to detect movement. However, to detect the direction ...
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0answers
90 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 ...
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1answer
58 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 ...
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0answers
156 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 ...
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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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1answer
459 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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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 ...
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2answers
71 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 ...
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0answers
31 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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0answers
49 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 ...
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1answer
320 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 ...
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1answer
598 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 ...
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1answer
3k views

Radar signal processing - Difference between range gate/range bin

In learning about radar signal processing, I see two different terms that sometimes seem to refer to the same thing, but sometimes different things: Range gate Range bin Usually, I interpret both to ...
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0answers
75 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 - ...
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1answer
164 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\...
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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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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. ...
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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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1answer
31 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? ...
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1answer
187 views

References ISAR - Inverse Synthetic Aperture Radar [closed]

Anybody know a reference to start understanding ISAR? Book or article. Thanks!
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1answer
217 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 ...
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1answer
3k views

Simulation of FMCW radar in frequency domain

I would like to simulate a FMCW radar in the frequency domain. I used the code (Matlab) I attached below. Specially I am interested in the phase spectrum of the beat signal. In a further research I ...
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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(...