The Event Horizon Telescope team of course deserves a huge amount of credit for their results. But it's interesting how they got there. ...

The Event Horizon Telescope team of course deserves a huge amount of credit for their results. But it's interesting how they got there. Here's an article with some non-technical discussion: https://fivethirtyeight.com/features/forget-the-black-hole-picture-check-out-the-sweet-technolog y-that-made-it-possible/ Their data is too noisy to actually create a black hole image. So they a

Recently I attended a coding seminar. The speaker very briefly reviewed the relevant history; first Hamming codes, ~1960: BCH codes, ~1970:...

Recently I attended a coding seminar. The speaker very briefly reviewed the relevant history; first Hamming codes, ~1960: BCH codes, ~1970: convolutional, 1995: polar, 2002: LDPC Clue me in - what was the advance in each case? I worked on a BCH project once, that seemed fairly efficient, how is it, or other algorithms, deficient? -- Rich

In the 60's I spent time as a BSEE student. Took a course using _Signals, Systems and Communication_ , Lathi , 1965 A generation later I found...

In the 60's I spent time as a BSEE student. Took a course using _Signals, Systems and Communication_ , Lathi , 1965 A generation later I found comp.dsp and obtained a copy of _Understanding Digital Signal Processing_ , Lyons, 2004 May I answers suitable for a bright high school student who reads eclectically {will account for what I've forgotten &/or never knew ;}. I've a germ of an ide...

Occasionally I attend recitals, where the student performs a concerto. It's a bit of a financial stretch for the music department to hire an...

Occasionally I attend recitals, where the student performs a concerto. It's a bit of a financial stretch for the music department to hire an orchestra, so a second pianist accompanies, acting as the orchestra. Thus someone has to condense the entire orchestral section down to a single instrument! A mighty job of compression indeed. How do they do that? The conductor isn't a mat...

Hi DSP people, I have a black-box system that ingests digital images, can perform a number of transformations on it, and later spits some of...

Hi DSP people, I have a black-box system that ingests digital images, can perform a number of transformations on it, and later spits some of them out in random order. My goal is to create an algorithm to generate digital images I sent into the system so that I can identify them when/if they come out, and tell which kind of transformations they have undergone. The images I put in have a n...

Is there any info on how to implement fft and ifft algorithms that aren't recursive? I'd like to possibly calculate a really long on inside a...

Is there any info on how to implement fft and ifft algorithms that aren't recursive? I'd like to possibly calculate a really long on inside a signal chain so attempting to compute a 2 second fft in one function call would probably be disastrous. -Matt

Hey Folks, I did some googling on this and couldn't get a satisfying answer. 1. What polarization is used to transmit? 2. What...

Hey Folks, I did some googling on this and couldn't get a satisfying answer. 1. What polarization is used to transmit? 2. What polarization is used to receive? The answer to question 2 would seem to be horizontal since that is the orientation of the antennas I've seen. But most broadcast TV antennas are (I believe) vertical. If I've got it right, then why do the tx/rx polarizati...

I found out today that Jerry had passed away last April at the age of 85. (= 17 Apr 2018). Jerry was a true polymath and had been quite a...

I found out today that Jerry had passed away last April at the age of 85. (= 17 Apr 2018). Jerry was a true polymath and had been quite a frequent and k= nowledgeable contributor to comp.dsp. Without formal training in the field,= his ability to dig deep and reason out details was simply astounding. Jerr= y will be missed. Clay

I am trying to make sense of some awful MATLAB code. The first thing it does is mirror the signal. By that I mean it doubles the array length,...

I am trying to make sense of some awful MATLAB code. The first thing it does is mirror the signal. By that I mean it doubles the array length, then puts a time-reversed signal at the newly created back half. So this would have the same amplitude spectum, but what else is going on? Possibly it increases the frequency resolution, as the time length is doubled. I wonder if the algorithm had som...

Someone is using this algorithm for high, low and band pass filter coefficients and wants to adapt it for band stop filters. ( y% is an...

Someone is using this algorithm for high, low and band pass filter coefficients and wants to adapt it for band stop filters. ( y% is an integer value that goes from filter length / 2 to +filter length / 2 ) IF y% = 0 THEN c = 1 ELSE IF BandPass THEN th1 = (fh - fl) * pi * y% ' Fhigh and Flow of passband th2 = (fh + fl) * pi * y% c = SIN(th1) * COS(th2) / th1 ...