Jeff's engineering management and design experience includes products and systems in the areas of AI, HPC, communications, oil exploration, defense electronics, space exploration, telecom, control systems, acoustic/audio algorithms, and industrial automation. He is a system architect and designer, as well as expert at software, hardware, and logic design, and a range of programming languages and operating systems. Jeff is president & CEO of Signalogic.

TI DSP Predictions

Jeff Brower September 19, 20075 comments

I think it might be interesting to blog a couple of "Texas Instruments DSP predictions". The following are just my opinion, they do not result in any way from inside / confidential information to which I'm privy in working closely with TI for many years. Of course I could be dead wrong, but at least I can say, "if they should occur, it would have a huge impact on the TI DSP developer community".

1) TI will offer real-time Linux running on their DSPs.

With Linux legal...


The Freshers Interview Guide

Jeff Brower September 19, 200720 comments

At Signalogic I'm in hiring mode right now, looking for a couple of entry-level engineers. After several interviews over the last few weeks I find troubling patterns... things young engineers should know, but they don't. Things they put on their resume but shouldn't, things they say or do in the interview they should not, and things they fail to say or do.

Then I see questions for "interview help" on DSP and FPGA tech groups that miss the point, asking about how to do...


Re: How to obtain impulse response of a room acoustics

Reply posted 1 month ago (01/23/2020)
WestRace-Dudelsound gives an excellent answer.  First, swept sine and MLS (pseudo random white noise) techniques emerged over the years as widely accepted methods,...
Nelson-When you mention "Audacity will add noise to an audio track when downsampling" are you referring to dither ?  I have found a lot of online discussion on...
Zeus101-First, your waveform displays do not match your description.  The first one (orig-spec_65570.png) should show 0 to 16 kHz, if the sampling rate was actually...

Re: phase change

Reply posted 3 months ago (11/18/2019)
Sharan-To see a simple example, multiply a sine signal with period "Fr" number of samples with a unit step that flips the amplitude half-way through:  y[n] = sin(2*pi*n/Fr)*(u[n]-2*u[n-Fr/2])That's...

Re: ADC and Complex Mixer Nyquist question

Reply posted 3 months ago (11/16/2019)
Rick-That is an exceptionally intuitive explanation.  Mixing is rotating after an FFT, I did not think of it that way before.  Thanks.-Jeff
Naumankalia-Are you saying you need multiple passbands, each with different amplitude ?  If so that would be arbitrary frequency response FIR filter design. ...

Re: Average Impulse Response from multiple measurements

Reply posted 7 months ago (08/11/2019)
Samp17-You can think of averaging in the time domain as somewhat of a convolution.  For thought purposes, consider one of your impulses as the input and another...

Re: reconstruct phase-shifted sine tone

Reply posted 7 months ago (08/04/2019)
Iosman-If you shift your already-windowed data in time, you will put the tapered window edges somewhere in the middle of the FFT frame, and create new edges (not...

Re: Machine learning and detection in noise

Reply posted 8 months ago (06/28/2019)
Gabrial-Deep learning is already being used for tone detection in presence of noise, on a far more complex basis than a basic sets of tones -- that's speech recognition.If...

Re: Window Impulse Response

Reply posted 8 months ago (06/26/2019)
Samp17-Normally windowing is needed for sliding FFT analysis, when there is "edge noise" due to sectioning data into frames on an arbitrary basis (i.e. some "frame...

Re: Pool Ball Pendulum Animation in MATLAB

Reply posted 8 months ago (06/13/2019)
Rick-First the snapshots look good.  Seems you indeed have the simulation working correctly.To confirm your chirp theory, you can add spectrogram type output to...

Re: Pool Ball Pendulum Animation in MATLAB

Reply posted 9 months ago (06/11/2019)
Rick-With this are you able to answer the aliasing question ?  Also can Matlab create an animated gif that you can post somewhere and we can see ?-Jeff

Re: Fixed Point Library for Python

Reply posted 9 months ago (06/11/2019)
Sml-Everything "DSP focused" or DSP centric is slowly dying, thanks to TI's brain lock on AI.  Total disaster that is.Deep learning is where you can get extremely...

Re: Sign of the magnitude difference

Reply posted 9 months ago (06/11/2019)
Sudarshan-Hmm seems like they stuck you on a legacy system.  Well, that is engineering, it happens to everyone :)To think about this, consider just real numbers. ...

Re: Sign of the magnitude difference

Reply posted 9 months ago (06/10/2019)
Sudarshan-So what are really saying ?  You cannot simply calculate |z1| -|z2|, for whatever reason ?  I.e. you no longer have z1 and z2 separately, but you do...

Re: Is this time-domain aliasing?

Reply posted 9 months ago (05/27/2019)
Rick-In that case would there be high frequencies we can't see in between balls ?  Could that be tested by hanging some very light weight but stiff strings in...

Re: Spammers are getting more sophisticated

Reply posted 9 months ago (05/21/2019)
Stephane-After deleting the link, can you "lock" the thread ?  And maybe add a little "info" icon explaining reasons why threads get locked.Spammers get more sophisticated,...

Re: AD9601 with 200MSPS connected to DSP

Reply posted 9 months ago (05/16/2019)
J Aranguren-Yes former DSP guys migrating en masse !As Mr. Miyagi would say, you guys have "good chance", probably very good.  TI can't win those seats because...

Re: AD9601 with 200MSPS connected to DSP

Reply posted 9 months ago (05/16/2019)
J Aranguren-A tangent ... I used to work so closely with TI that it felt like I worked there.  Weekly even daily dialogs about various projects and efforts.  Intel...

Re: Discrete Wavelet Transform (DWT) Filter Bank question

Reply posted 9 months ago (05/13/2019)
Andrey-Have you thought about contacting the Wikipedia author and asking whether the "new" terminology should be changed to say "repeated", "updated", or as the...
Szak1592-You:  "I'm pretty sure my code implements the equations for overlap save correctly."Rick:  "I don't think your code is working properly."My money is on...

Re: Todo List: Improvements to the Related Sites

Reply posted 10 months ago (05/02/2019)
Matthew-Right.  User info should include:  1) how many posts, both original and answers  2) upvotes or thumbs-up or something that indicates answer quality ...

Re: picture inter and intra prediction

Reply posted 10 months ago (04/30/2019)
Sharan-I see that you're not getting any replies.  Googling inter vs. intra prediction brings up lots of hits.  One example I found explains what criteria H.264...
learn-Based on your comment about gamma compression, isn't that what you want ?  A gamma of about 0.857 would reduce your number bits from 14 to 12.  It might...

Re: Auto Correlation in DSP processor

Reply posted 11 months ago (03/18/2019)
Mathedoomm-If you're using LabVIEW and testing/simulating solely with PCs at this point, then weetabixharry's suggestion is very good.  Searching for:  autocorrelation...

Re: The Spectral Complexity of a Single Musical Note

Reply posted 12 months ago (03/08/2019)
Rick- I did a quick survey on automatic music transcription.  It sounds to me like it's an even more difficult problem than speech recognition.  Speech also exhibits...

Re: The Spectral Complexity of a Single Musical Note

Reply posted 1 year ago (02/18/2019)
Rick, does the article say anything about mic / data acquisition system specs ?  The plot seems to me a tad suspicious in that "all shape seems to be lost" around...
ReachRF-One comment I might make would be to be careful using the word "domain".  To see Doppler shift you are transforming data from time to frequency domain ......
Nelson-How much "some calculation" are you willing to tolerate and why is there an a-priori need to know ?  The excellent answers from Bholzmayer, Kaz, and Slartibart...

Re: C++ Package for DSP

Reply posted 1 year ago (11/19/2018)
Ahmed-First, I think the core of GNU radio is C++, maybe that's usable for you.  Second you might look at OpenCV.  That's image processing, but their code seems...

Re: Machine learning and detection in noise

Reply posted 1 year ago (09/19/2018)
Tech Nomad-Since you're open to a machine learning solution and seemingly not tied to dedicated algorithms, I would suggest a deep learning approach.  Generate...
Jshowa-> Cause a failure when accessing the array at data[n-1] and data[n-2]> on the first and second iterations?Yes it would, so expanding on my simple example,...
Jshowa-Y(J)S is spot on.  They want to avoid overwriting input data in a short range of 3 points (length of filter, M = 3), so they temporarily use input points...

Re: DC Blocking unexpected results

Reply posted 2 years ago (08/15/2018)
Tony-Great thread with lots of detailed, helpful discussion but seems it's still not completely resolved from your perspective.  I was going back to your original...
Kaz-You forgot MobaXterm and scp, but yeah that sounds about right.  I've used all of these at one time or another, they are effective and easy enough to learn...
Friedman-That made me laugh.  I don't recall being able to do write-in answers for the SAT, but that sure was one case where it was needed.-Jeff

Re: Fundamental frequency of a Guitar string

Reply posted 2 years ago (07/09/2018)
Donvoth-I did this Google search:  FFT algorithm for guitar tuningand the whole first page has good links, including some pro and con discussion on whether to use...

Re: Fundamental frequency of a Guitar string

Reply posted 2 years ago (07/03/2018)
Donvoth-That series of Fujitsu uP has a 10-bit A/D converter:http://www.fujitsu.com/downloads/MICRO/fma/mcu/ds9...My guess is that Roland uses this, acquires a few...

Re: Fundamental frequency of a Guitar string

Reply posted 2 years ago (07/02/2018)
Donvoth-Are you able to see the part number of the Zilog micro ?-Jeff

Re: Fundamental frequency of a Guitar string

Reply posted 2 years ago (06/30/2018)
Donvoth-As other answers have mentioned, converting from a 60 - 6000 Hz time domain waveform to "a series of pulses" is key.  This conversion is the fundamental,...
Dsavio-My comment is in the spirit of the time-worn saying "if something looks too good to be true, then it probably is".  During the process you describe, time...

Re: DSP board selection

Reply posted 2 years ago (06/13/2018)
Naumankalia, you say "DSP board", so in addition to your ADC/DAC specs, the card also needs a DSP ?  If so, what level of processing is needed; i.e. how many cores,...

Re: Inverse filter

Reply posted 2 years ago (06/09/2018)
Kaz-I've calculated:  H(s) = Y(s)/X(s)many times before before but to obtain reliable results I usually had to do two things (i) use 32-bit fixed-point FFT results,...
Kam-With three outputs, and the relatively small size of your ballroom, I think you would be in reasonable shape.  As long as cost is not prohibitive, there is...
Kam-> the dsp can only recognize 3 speakers (left, middle, and right)Does that mean you have three (3) outputs ?> the amp allows me to individually adjust...
Kam-But you only have one output, correct ?  The typical approach is one output per speaker, get the system up and running, then take careful seating measurements...
Kam-Many years ago I used to help guys with sound systems in concert halls, churches, etc.One thing always of concern:  equalizing sound arrival at certain points...
Milad-For IIR filters, group delay is notoriously difficult to measure at frequency response transition regions.  Phase unwrapping has to be performed carefully...

Re: CIC filters with decimation ratio jitter

Reply posted 2 years ago (05/05/2018)
"It pains you", hehe.  Yeah I can see that.  Maybe Ned is wiser than he looks, if he knows the number of samples he consumes (seems like a reasonable assumption)...

Re: CIC filters with decimation ratio jitter

Reply posted 2 years ago (05/04/2018)
JMS-Trying to get a mental picture ... you're saying that you have a sample buffer (or more than one, at 1.024 MHz) and the "downstream consumer" is taking an...

Re: Proper Overflow Adjustment

Reply posted 2 years ago (03/10/2018)
Abb-I think first you may want to be absolutely sure it's overflow or clipping that you have.  My suggestion is to look carefully (zoom in to sample level), starting...

Re: Proper Overflow Adjustment

Reply posted 2 years ago (03/10/2018)
Abb, I'm not clear ... you're using floating-point to look at sampled audio data ?  How did you get the data in the first place ?  Most (by far) audio devices...
Tim, thanks, right.  Theoretically, cascading 1st or 2nd order filers is intended to help.  What I was concerned about is during testing if something is slightly...
Jens-Ok thanks.  My first thought was that cascading anything IIR might run into numerical issues, especially so if fixed-point is somewhere in the picture. ...
Jens-Are you testing filter implementation on a floating-point platform or device ?  Or a fixed-point device ... TI DSP for example.-Jeff

Re: overlapping acquired audio data

Reply posted 2 years ago (02/22/2018)
Max-What analysis are you looking at, if not spectral that would require windowing ?  Windowing is pretty much a spectral processing thing (FFT, wavelet, Gabor,...
Simon-Got it.  For SnapDragon I can't make an OpenCV specific or other recommendation now, but possibly in a month or two, as for a major outfit we're doing a deep...
Simon-Are you unable to answer my question for proprietary or other reasons; i.e. which platform you're using (which CPU or SoC) and how many cores you have available...
Simon-Have you looked at OpenCV ?  What platform are you running on and how many cores ?OpenCV includes image convolution, and has the *potential* to be fast depending...

Re: Artifacts in Time Varying IIR Filters

Reply posted 2 years ago (01/05/2018)
Dan-You have recieved so much great theoretical advice, for sure you will get it working fine.I would like to add some advice on the practical side.  Many years...

Re: AGC on FPGA

Reply posted 2 years ago (11/14/2017)
b2508 I see several good algorithm suggestions here, but assuming your current algorithm is fine as-is, do you have available a faster clock ?  Or can you synthesize...

Re: Estimate battery run-time in real-time

Reply posted 2 years ago (11/09/2017)
Markus-Suggest to take a look at battery manufacturers' data sheets, for example:https://www.duracell.com/en-us/techlibrary/product...or closely related chip datasheet,...

Re: What is Windowing and when/why do we need it?

Reply posted 2 years ago (11/03/2017)
Sometimes we have to teach new hires about windowing on a basic level.  They've already seen it in school, but maybe don't "feel" the need, and just think of it...
Ced yeah I'm not sure either.  I think at one time it was automatic and you had to make an effort to get it to prompt you:https://answers.microsoft.com/en-us/windowslive/fo...Even...
Ced so what you're saying is that JJ, by using the Add Connections Features, essentially gave LinkedIn permission to read the contact list(s) somewhere on his machine,...

Re: audio artifacts sleuthing

Reply posted 2 years ago (09/05/2017)
David - yeah it seems you're pretty good at artifact analysis.  After a lot of prodding we got more info from our customer and they did have issues with their test...

audio artifacts sleuthing

New thread started 3 years ago
I've uploaded a wav file (http://signalogic.com/wav_files/evs_16khz_13200bps_CH.wav) that was produced by extracting payloads from an EVS (codec) pcap sent by our...
It looks like Jaewook means he adapted this to use with the ACF:http://users.monash.edu/~lloyd/tildeMML/KLhttps://stats.stackexchange.com/questions/14673/me...Although...

Re: Need Help In Interpreting Curves in a Chart

Reply posted 3 years ago (05/13/2017)
I would guess (i) they're trying to show a rate, i.e. some number of iterations per sec, (ii) time/s is a time value normalized with another time value (but I have...

Re: Who clones DSP56362?

Reply posted 3 years ago (03/09/2017)
Tony-Does it look something like this:  replacement.com.tw/sst49lf008a.jpgand it's socketed ?-Jeff

Re: Who clones DSP56362?

Reply posted 3 years ago (03/08/2017)
Tony-The 56362 data sheet is here:http://www.nxp.com/assets/documents/data/en/data-s...As Joe mentions, it contains a 30k word program ROM.  In those days (15+...

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