Questions tagged [beamforming]
Forming a beam (directional gain) and, sometimes, shifting the beam direction.
78
questions
10
votes
1answer
226 views
How can one improve the robustness of adaptive beamformers to signal mismatches?
Compared to standard (conventional) beamformers, adaptive beamformers such as minimum variance distortionless response (MVDR) have much better resolution and interference nulling capabilities. Briefly,...
9
votes
3answers
420 views
Practical wideband digital beamforming for large arrays in radar applications
I do understand the mathematics behind digital beamforming but I am not sure how such systems are practically implemented. For example, in a typical wideband FMCW radar operating in S-band, the (...
8
votes
1answer
2k views
Difference between 'conventional' and 'adaptive' beamformers?
This might be a terminology question but I am not sure.
Basically, what is the difference between conventional beamformers, and adaptive beamformers? I thought that all beamformers were inherently ...
7
votes
2answers
951 views
Can a narrowband beamformer be used for speech separation
In my master thesis I am trying to implement a beamformer.
I've already done the delay-sum part 1 year ago. I have been told:
in FIR filtering we can do
FFT --> null the unwanted frequency bin --> ...
4
votes
2answers
2k views
Intuitive interpretation of Fourier transform in beamforming
When applying Fourier transform in time domain the signal will be carried to frequency domain. And when we apply Fourier transform in spatial domain the signal will be carried to directivity domain.
...
4
votes
1answer
312 views
Is it possible to do further beamforming on already beamformed data?
I've a circular array of eight FM antennas. I'm doing digital beamforming to form eight beams with the following beam patterns:
The objective is to reduce my side lobes even further, and to get ...
4
votes
1answer
903 views
Calculating Beam pattern, Directivity of microphone array
As answered in Relationship of Fourier Transform and Spatial Directivity Pattern the relation between directivity pattern and weights is given. But I am bit confused, I have Beamformer weights (...
4
votes
0answers
257 views
Question on spatial sampling for non-linear and/or non-uniform arrays
I am a little confused as to how to compute the nyquist criterion for a sensor array that is not linear, and/or non-uniform. For the linear, uniformly spaced case, the spatial nyquist is delimited by ...
3
votes
2answers
1k views
Relationship of Fourier Transform and Spatial Directivity Pattern
I am reading over and over the Section 1.2 of most understandable mic array tutorial for me .
A sound wave is dependent on time and space which can be observed in the great link.
But I can't ...
3
votes
2answers
86 views
Proving that a product of matrices invertible
Given $R_x$ a Positive Definite (PD) covariance matrix of size $M\times M$ and $C$ a full rank $M \times N$ matrix, I want to prove that $C^* R_x^{-1} C$ is invertible to derive the Linearly ...
3
votes
1answer
55 views
Beamforming back lobes question
When performing a conventional digital beamforming I see in some textbooks they show beam patterns as
where the arrival angle ranges between -90 to 90 degrees. But then other places show the full ...
3
votes
2answers
250 views
Tetrahedral microphone array beamforming
I have a microphone array of 4 channels taken as channels [6,10,22,26] from Eigenmike spherical microphone array. I wish to do 3D beamforming and create $8\times 4$ beams, 4-elevations with 8 ...
3
votes
0answers
56 views
Beamformer implementation methods
I'm currently reading articles about the different type of beamformers. This spatial filtering is gonna be used for acoustic purposes, to focus the beam on the person we need to hear talking in a ...
3
votes
0answers
58 views
Physical Interpretation of $\mathbf A$ beamforming Matrix
The directivity of an array is defined as:
$$ D = \frac{1}{2} \int_{-1}^{1} \lvert B_{u}(u)\rvert^{2} du$$
Where $B_{u}(\cdot) = \mathbf{w}^{H} \mathbf{v}(\cdot) $ is the beampattern of the array in ...
2
votes
3answers
100 views
Amplify Sound From Known Direction
I have microphone array which records sound. There is one main sound which direction I know and some noises in the background. Now I want to selectively amplify sound from known direction. This looks ...
2
votes
1answer
796 views
DSP with 8+ inputs for simple beamforming
Does anyone know of a DSP that is cheap and has 8+ inputs (8 I2s mics) and that can perform beam forming calculations? I'm super new to circuit design so preferably one thats beginner friendly.
...
2
votes
1answer
1k views
Directivity Pattern of microphone array
Directivity pattern of a microphone array is fourier transfrom of microphone weight values. By modifying the amplitude weights, we can modify the shape of the directivity pattern.
I can really see ...
2
votes
2answers
68 views
How to derive the “well-known” solution to Unconstrained Array Gain?
Can someone point me to a webpage or other resource that shows how to analytically solve the beamformer Unconstrained Array Gain expression in Henry Cox's 1987 IEEE paper "Robust Adaptive ...
2
votes
1answer
1k views
Delay and sum Beamforming
What is the difference between the weight vector (w) and the steering vector a(Īø)?
I initially assumed they were the same thing, but the literature seems to be to be a bit fuzzy with this (or maybe ...
2
votes
1answer
248 views
Would a visible light beamforming “telescope” be feasible?
If you had a phased array of high speed photodiodes that were spaced sufficiently far apart, would it be possible to apply beamforming theory to create a steerable visible light "telescope"?
...
1
vote
2answers
328 views
how to calculate the maximum obtainable directivity for a microphone array?
Introduction
The relationship between the maximum obtainable directivity and aperture of an antenna is described by:
$$ D = \frac{4\pi A_e}{\lambda^2} $$
Where $D$ is the directivity, $A_e$ the ...
1
vote
1answer
2k views
Calculating covariance matrix for MVDR beamforming
I am trying to calculate the covariance matrix that is required for the calculation of an MVDR beamformer. I am getting confused as to how to calculate it. I have an array of 3 microphones each with a ...
1
vote
1answer
48 views
Radar type application for narrow band only?
Not sure if this is the proper forum to ask this question, but still I am trying my luck.
I am looking for an application (in any area, medical, defence, or any other area) if exist, such that we want ...
1
vote
1answer
129 views
Implementing MVDR beamformer in the STFT domain
I am trying to implement an MVDR beamformer for the first time. I was reading a couple of papers and books with many different notations and I am a bit confused.
In my case, without loss of ...
1
vote
1answer
273 views
Which parameters defines a polar plot?
I need to convert a polar plot into a short array of 3-5 values. This array should describe the polar plot as best as possible.
For example, I know that I can use the beamwidth which is also known as ...
1
vote
2answers
193 views
What does the $n$ do in $1/(j \omega)^n$
I'm currently working through a research paper on beam forming. In this paper a magnitude compensation is introduced to compensate for frequency dependency. Due to other calculations low frequencies ...
1
vote
1answer
101 views
What is the best way to show beamformer enhances signal of interest over interference
I need to study an array's performance in terms of interference.
I have already analyzed the array's white noise gain which is the ratio of output and input SNR of the beamformer i.e. $\rm{SNR_o} / {...
1
vote
1answer
193 views
Relationship between matrix rank and beamforming
I always encounter the term matrix rank in papers related to beamforming. I am only familiar with the basics of beamforming (delay sum beamformer, basic capon). Can someone explain the significance of ...
1
vote
1answer
206 views
Filter signal for beamforming and phase response
I was wondering this for quite some time but couldnt find a satisfied answer. Seems like not a lot worry about phase response in general. But maybe I'm thinking about it in a wrong way...
I want to ...
1
vote
1answer
976 views
Spatial sampling frequency equation
Upon reading this microphone array tutorial, I'm stuck in the following piece:
The spatial sampling frequency along the x-axis is given by
$f_{x_s} = \frac{\sin \theta \cos \phi}{\lambda}$
where $\...
1
vote
1answer
1k views
Difference between Uniform Linear Array (ULA) 3 dB beamwidth and bearing resolution
Is there a difference between linear array 3dB beam width and linear array bearing resolution ?
1
vote
1answer
1k views
Plotting antenna pattern in MATLAB
I have a beamformed output, say
y = weights * signal,
where the signal is gaussian,i.e signal = randn( 1 , 1e5 ).
Now I want ...
1
vote
0answers
43 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)...
1
vote
0answers
344 views
Time-Delay beamforming delay computation
I'm trying to implement a beamforming algorithm in python and I'm stuck with the time-delay computation for a rectangular array.
I'm using the following equation to compute the delays based on the ...
1
vote
0answers
146 views
Superdirectivity Beamformer for Circular microphone array
The matrix below represents the inverse of correlation matrix assuming diffuse noise field. I am unable to figure out the values of the elements of this matrix.
how to calculate $c_{M}(\omega)$ ?
1
vote
0answers
134 views
Beam pattern for a linear array comprised of rectangular transducers
I am looking for the beam pattern of a linear array with uniform spacing, $d$, between $n$ elements.
I know for an array comprised of circular pistons it can be derived from
$$\frac{1}{n}\frac{\sin[...
1
vote
0answers
76 views
The Rank Of Broadband LCMV Beamformer Constraint Matrix
So I am wondering why I keep seeing that the rank of the LCMV Broadband Constraint Matrix is equal to the number of constraints, when in practice, I find that the rank is only 1. This is precluding me ...
0
votes
2answers
1k views
Delay-and-sum beamforming: implementing steering in C
I am currently trying to understand how delay-and-sum beamforming works.
I have found this website which explains the process of this technique very well in which the following C code is provided:
<...
0
votes
1answer
340 views
Beam resolution improvement of linear array using MVDR beamformer
One of the major advantages of using MVDR beam former is to improve bearing resolution as compared to conventional delay & sum beam forming. The bearing resolution is defined by 3 dB beam width of ...
0
votes
2answers
20 views
Multi-input Single-output communication system
In case of communication in MISO system, if we have a system of 4 x 1, which means 4 transmitter with 1 receiver. Will the received signal be a vector of dimension 4 x 1 ? Or it will be 1 x 1 since ...
0
votes
1answer
41 views
What is the driving Voltage?
While I was looking into ultrasonic transducer in order to transmit and receive a beam, I came across specification of a transducer stating driving voltage as 20Vrms. I am not sure what actually does ...
0
votes
2answers
2k views
what is an alpha filter?
Currently, I'm working on adaptive beamforming using LMS approach, so they change the value of the step factor adaptively in which one of the steps is to pass the weight vector through an alpha filter....
0
votes
2answers
866 views
Beam width of linear array using MVDR beamformer
I did delay and sum beamforming technique and MVDR beamforming technique in MATLAB in ...
0
votes
1answer
475 views
What is homogeneous noise field?
What is the formal definition of homogeneous noise field? Is there any example of it?
Thanks.
0
votes
1answer
2k views
Beamforming using MATLAB
I'm attempting to beamform some data which has signals coming from all directions in a 180 degree range.
I found an example of using the phased array toolbox, in MATLAB, to beamform a signal in https:...
0
votes
1answer
51 views
Why is beamforming needed in 5G?
With the advent of 5G Era, base station density
increases, the cell radius decreases, and LOS propagation
gets more dominant. So, why do we need for beamforming in 5G NR, although we have smaller ...
0
votes
1answer
37 views
Is there a term called “Fourier Beamforming”?
I understand delay and sum beamforming, where we want to add the signals obtained from different sensors. But adding different time samples from different element of the array depending on the angle ...
0
votes
2answers
59 views
How multi layer map to different beams in LTE Beamforming
I understand for SU-MIMO Beamforming single layer maps to all antennas with phase shift applied to create beam. Also I understand in this case all beams will be carrying same signal (say s1).
But in ...
0
votes
1answer
345 views
How to compute beam pattern given a delay-and-sum filter in spectral domain?
Given a two-mic system (the mic spacing $d$ is known), how can I compute the beam pattern (see the Figure below) over frequency and angle $g(f,\theta)$ for a pair of spectral filters ($H_0$ for ...
0
votes
2answers
213 views
MVDR Beamformer, minimize but do not change pattern in main beam
Is there a way to minimize all signals that are not coming from the mainbeam?
I would like to keep the main beam, or at least +-3Ā° around the main peak stable.
When I estimate the covariance from ...
