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## 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!

## my geophysics CV

inI just updated the Microsoft Word and PDF versions of my CV on my home page to reflect the fact that I got a Ph.D. at the end of May and to list...

I just updated the Microsoft Word and PDF versions of my CV on my home page to reflect the fact that I got a Ph.D. at the end of May and to list five new papers, but haven't yet updated the HTML version so I just deleted that for now. The direct link for the PDF version is http://www.nfld.com/~dalton/dalton-cv-web-2019.pdf Constructive criticism is welcome. Also I have put my Ph.D...

## Researchers: Error-Correction Codes hold Spacetime Together

inSome articles in the pop-science press appeared this week on the topic; so I traced down a paper by the researchers. Interestingly, I heard a...

Some articles in the pop-science press appeared this week on the topic; so I traced down a paper by the researchers. Interestingly, I heard a similar idea floated in the 1990's, but apparently nothing was published at the time. https://arxiv.org/abs/1411.7041 Steve

## region of convergence of z transform - why bother

inYes I understand the theory, left handed and right-handed sequences. we can= have two z transfer functions the same but one is left hand sided...

Yes I understand the theory, left handed and right-handed sequences. we can= have two z transfer functions the same but one is left hand sided and the = other right. A great deal is spent explaining this but exactly what is the use in the fi= rst place of left-handed sequences as they are non-causal. I see in countle= ss book examples of sequences going backwards in time - find the z-transfe...

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