nauman kalia (@naumankalia)
HiSuppose there are two continuous signals of same frequency say 4 KHz. The delay/time corresponding to its one cycle is around 250 us. If we delay one signal by...
Hi CedronCan you kindly explain further the calculations you have done above? How these effect correlation results?Thanks
Hi,Thanks for help. Yes, you are right. There are multiple ways to find delay b/w two signals but currently i am interested in measuring delay using correlation...
Hello mospelThanks for reply. yes your are right but wavelength/2 spacing is requirement of standard beam forming techniques. Here the problem i am facing is somewhat...
Hi ChalilThanks for help. I am lost here somehow that why correlation results are depending upon frequency of signals? Let us forget about 2 sensors geometry, i...
Hi ChalilThanks very much for help. I have used your kind advise but still the delays measured by your 'delay_estimate' function or MATLAB 'finddelay' function i.e. -3.255e-07s...
Hi allI am simulating signals on two hydrophones H1 and H2 of linear array which are at a distance 'd' from each other. The geometry is shown below:Assuming Plane...
Hi allIs there any way to measure frequency deviation in a recorded frequency modulated time domain data? The little research i have done on net mostly concerns...
Hi Playbel
Many thanks again for such detailed elaboration as well as literature. You correctly pointed out that the expressions used by me were incomplete, or...
Hi PlaybelMany many thanks for help and also for 'MATLAB Code'. What i conclude from your last reply is that in practical field using real hydrophones as two monopoles,...
Hi Platybel Thanks very much for help. Will this factor 'j' appears only in simulations due to mathematics? I mean if I do practical experiment by making dipole...
Hi JeffIt is not the amplitude of two hydrophones i am plotting in Dipole graph, it is the amplitude of two Dipoles formed using two methods i mentioned before. At...
Hi jeffThe second graph i shared shows the variation of amplitude when angle changes from 0 to 360 deg (following sine pattern).Currently, I am doing only simulations...
Hi Sagar1.As Length of water Tank is 12m, Rx array and Tx probe are placed apart around 8.9m lengthwise. As depth of Tank is 8m, both Rx array and Tx probe are immersed...
Hi all I am doing some research on High Frequency Linear Array beam forming (for imaging sonar).For that purpose, a linear Rx Array of 100 channels have been constructed...
Hi JeffI meant that the SINE Dipoles made using two methods should have same amplitude and phase relative to each other. In my understanding, both methods of Dipole...
Hi PlatybelI am calling these SINE Dipoles as they follows sine pattern. If I plot signal magnitude of both Sine_Dipole_1 and Sine_Dipole_2 against angles from...
Hi all. I am trying to do MATLAB simulations for generation of SINE Dipole using two hydrophones spaced distance 'd' apart for signal coming from direction 'DOA'....
Hi allI wanted to generate broadband noise of specific amplitude for my simulations. To do so, i generated a random noise using MATLAB randn command and then design...
Hi allI have a digitized acoustic data of length L in which a pulsed signal (chirp) of finite duration and bandwidth is merged starting at some time instant t1...
HiAs i described in my first post, i short both differential inputs of ADC to measure self noise of system. Secondly, +/-5 V is the input scale of ADC
Thanks for reply. I am sorry i could not clearly explain the purpose of this scheme. My main purpose is to determine practically (not theoretically) Hardware noise...
Thanks for reply. I am sorry i could not clearly explain the purpose of this scheme. My main purpose is to determine practically (not theoretically) Hardware noise...
Thanks for reply. I am sorry i could not clearly explain the purpose of this scheme. My main purpose is to determine practically (not theoretically) Hardware noise...
Hi allI am trying to calculate self noise of a digitization system with differential inputs.For this purpose, i select a differential channel, set input range to...
Thanks for clarification. I think the phase unwrapping phenomenon will effect time domain implementation of beam former where time delays are being calculated depending...
Thanks for reply. Can you kindly explain the phase unwrapping phenomenon w.r.t. frequency domain delay-sum beam former? Currently, I am using spatial FFT technique...
Thanks for reply. I am using chebyshev array shading with Delay-Sum beam former in frequency domain.
Thanks very much for detailed reply. I am not facing 'grating lobes' issue as my array coverage area is very short i.e. <15 deg and no grating lobes can occur...
Hi allI am working on beam forming of high frequency (>400 KHz) linear array for imaging sonar. I have gathered sensor data of 80 channel linear array sub merged...
Hi allI am in search of DSP board which have at least 5 ADCs (16 bit, Bipolar, 192 K samples/s/channel) and one DAC (16 bi,t Bipolar, 192 K samples/s/channel)....
Thanks for help . If i understand correctly, i cannot measure accurate phase difference b/w two sinusoidal signals using FFT method if the phase difference b/w them...
Thanks for help. I am trying to implement sin(wt+phi) formula. I know my frequency i.e. 100 KHz and my sampling rate e.g. 400 Ksamples/s, kindly guide me how to...
I am trying to understand how to find phase difference b/w two real sinusoidal signals and then align the phases of two sinusoidal signals using this difference....
Thanks for reply. Your work seems quite close to what i want to do (calibration including sensors+preamps was next step for me). Can you kindly explain did you...
Thanks for reply. I am trying to calibrate electronics of linear array having three sensors. Only if calibrated properly, i will be able to find correct DOA of signals...
Hi allI have simultaneously recorded data coming from three pre-amplifiers with same input applied to these pre-amps. After post analysis, i found that there are...
Hi cogwsnThe article is clear in case of single pulse as i understand it. As i have to insert multiple pulses at different locations with different SNRs, should...
Hello allI need to generate random white Gaussian noise of some x second length. I also need to add multiple sinusoidal pulses of y (y<<x) duration and SNRs...
Thanks Tim Wescott for your help. The sensitivity is flat in desired frequency band. The actual sensitivity was -206 dB ref upa and i have included 10 dB gain of...
Thanks for help.The transducer sensitivity is almost flat across desired frequencies.The confusion is about that 1upa will yield "-196 dBVrms" as literature says...
Hi allI am trying to record underwater noise in terms of pressure(upa) time series using voltage output hydrophone having receive sensitivity of -196 dB ref vrms/upa....
The first 10 chunks corresponds to a range (converted from time corresponding to 10 chunks) where no target was being placed.
Thanks for reply. Target is present in the data for sure but after 10 no of data chunks. First 10 chunks contain reverberation only.
Hi all I am working on colored noise (reverberation) rejection algorithms. One approach present in literature is through prewhitening filter. In this approach as...
Dear KrasinThanks for reply. My question was how to produce simulated input (having c/2B range separation b/w them) to match filter.Is there any literature reference...
Hi allI am working on Match Filter/Correlation algorithms for pulsed radar/sonar. The literature says that if we use CW Pulse, the range resolution is defined by...
Hello allCan any one kindly explain the difference b/w array beam width (3 dB) and array bearing resolution and what is the relation b/w them?Regards
Thanks Dr Mike for help. I will try to implement this technique. Will this cater(smooth) for 'clicks' due to phase mismatch when shifting from one beam/channel...
Dear JOSThanks for help. I am unfortunately not familiar with cross fading. Can you kindly indicate some useful literature in this regard?Thanks
Hi allI am working on #Beamforming of linear array of microphones and one of my tasks is to provide real time audio of user selected beams. Currently, i am working...
My concern is boundary (surface/bottom) reverberations mainly and purpose is to improve beam width some how for reduction in effective reverberation.
Thanks. You are right, i think i have to simulate MVDR beampattern for simplest case (i.e. zero interference) and try to estimate beamwidth.Best Regards
Thanks. You are right, i think i have to simulate the beamp attern for simplest case (i.e. zero interference) and try to estimate beamwidthRegards
Thanks for helping. Actually i was seeing this algorithm with perspective of improving "reverberation index" in active sonar equation which depends upon Bandwidth...
Thanks for helping. Actually i was seeing this with respect to improving "Reverberation Index" in active sonar equation which mainly depends upon Bandwidth and 3dB...
Hi
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...
Dear Tim WescottThanks for reply. I have done some rough sonar calculations for estimations of specifications for ADC and preamplifiers and are attaches as Queries.docIf...
Dear SirThanks for your time and sorry for late response. You are right that for short ranges, active sonar will be reverberation limited but in designing of active...
Dear ShahramThanks for reply. You are rigth but some times at higher frequencies, it is difficult to maintain lemda/2 spacing in an array due to sensors physical...
HiThe linear array directivity index (DI) can be calculated as 10log10(n) or 10log10(2L/lemda) where n is no of sensors in linear array, L is acoustic length/aperture...
Hello allI am working on modelling and simulations of synthetic aperture sonar at component/subsystem level. I have started with standard sonar equations for calculating...
Dear Dr. MikeThanks for help. I have used MATLAB based acoustic toolbox some time ago which uses bellhop and other ray tracing models for transmission loss calculations....
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