## Forums More comp.dsp

## Ultrasound beamforming

inHi, A typical beamforming method widely used in ultrasound technology is to apply delays between channels and then summing the signals of all the...

Hi, A typical beamforming method widely used in ultrasound technology is to apply delays between channels and then summing the signals of all the channels. However, when properly calculated delays are applied, it could happen that the phase of the arriving signal is 180 deegres (half the ultrasound wavelength) shifted between channels and summed amplitude is decreased. This results

## Load disturbance sensitivity function in control loops

Hi, I'm a bit confused about the load disturbance sensitivity function in control loops. Basically, I have a design where the load disturbance...

Hi, I'm a bit confused about the load disturbance sensitivity function in control loops. Basically, I have a design where the load disturbance sensitivity function has a maximum of 5 at a frequency of 300 Hz. I'm not sure I understand this metric correctly. Does it mean that a load variation of 10% at a frequency of 300 Hz would create a variation 5 times higher on the output? The formula...

## Why does it say "Toeplitz matrix, so we only need to calculate the first row and column of the matrix"?

inHi, I know Toeplitz matrix has the same value along its diagnose line. I think the first row value gives all the value of the Toeplitz matrix,...

Hi, I know Toeplitz matrix has the same value along its diagnose line. I think the first row value gives all the value of the Toeplitz matrix, why the author said in his way. /////////////// Toeplitz matrix, so we only need to calculate the first row and column of the matrix Thanks for reading

## DCT in video compression

inThe mp3 standard uses the discrete cosine transform (DCT), rather than the full DFT. Doesn't that imply throwing away half the...

The mp3 standard uses the discrete cosine transform (DCT), rather than the full DFT. Doesn't that imply throwing away half the information? Can anyone explain this? -- Rich

## Counter and length of count

inSomebody check the sums which was fun working out. I have a sensor which gives out 4096 pulses per revolution. This is attached to a motor...

Somebody check the sums which was fun working out. I have a sensor which gives out 4096 pulses per revolution. This is attached to a motor which turns at 1000 rpm. I need to count by using an integer in increments defined by a signed 64 bit integer. The question is, how long can it count for at this speed before the integer overflows? 64 bits is about + or - 9.23 x10^18 count in on

## FFT Beamforming

inHi, Im an undergraduate student and I have researched how to estimate the direction of arrival of a signal using a FFT. I understand how to use...

Hi, Im an undergraduate student and I have researched how to estimate the direction of arrival of a signal using a FFT. I understand how to use it and how to implement the algorithm, but im unsure as to why when performing an FFT on spatially separated data this yields an angle? Thanks, Jan

## How to use IFFT to get the system impulse response?

inHello all, I have got the system transfer function of a two port network in frequency domain,the frequency range is from 2Ghz to 12GHz.IFFT is...

Hello all, I have got the system transfer function of a two port network in frequency domain,the frequency range is from 2Ghz to 12GHz.IFFT is used to get the time domain impulse response,but the result is complex ,not real.The impulse response of a system should be real.So,please give me some suggestions.thanks .

## Implementation of gain scheduling for PI controllers

inHi, I'm designing a controller for a boost converter. I'm able to find a set of gains that fit for all situations, but I get a slow response at...

Hi, I'm designing a controller for a boost converter. I'm able to find a set of gains that fit for all situations, but I get a slow response at full-load. I was thinking instead of using gain scheduling, 1 set of gains for little to no load and 1 set of gain when load is significant (say more than 25% of the maximum load). Now my question. What are the gotchas about gain scheduling? In bo...

## origin of "Bracewell interpolation"?

inI can across a really old Fortran program with a subroutine that interpolates a 1D array of N samples to 3N samples. It uses a 5-point operator,...

I can across a really old Fortran program with a subroutine that interpolates a 1D array of N samples to 3N samples. It uses a 5-point operator, and the comments describe it as Bracewell method, spline approximation to sinc. I haven't seen this before. Bracewell's 1995 book on Two-Dimensional Imaging had a formula for 6 nearest points. Did he publish a formula for 1D interpolation with 5 po...

## Microsoft is not the answer

Microsoft is the question the answer is no!

Microsoft is the question the answer is no!

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