### John Ehlers (@JohnEhlers)

BSEE and MSEE from University of Missouri. Doctoral studies at George Washington University. Started career as an antenna designer for Boeing Aircraft. Retired from Raytheon as Senior Engineering Fellow after 25 years.

## Re: Low-pass filter image data

Here is a super simple way to get the smoothing you want.  Just smooth the pixels from left to right with an EMA.  Then take that result and smooth it from right...

## Re: Adaptive filter and noise reduction

Stability is not an issue if you keep the poles inside the unit circle.

## Re: Adaptive filter and noise reduction

You may want to consider using an IIR filter.  Adaptive smoothing filters are used by technical analysis traders in Futures and Stocks.  You can Google such filter...

## Re: PhD in E.E. is it really worth it

Marcin:I can only tell you my story, and that may help.  I went back for my PhD after working in industry because I was gravitating toward management, and I really...

## Re: Who discovered the math of the digital polar discriminator?

Chuck:t[0] is the current sample.  t[1] is the last sample.  So, in terms of samples, the difference is unity.  Of course, time scales according to the sample...

looks good

## Re: Who discovered the math of the digital polar discriminator?

Analog FM precedes DSP by years, and so does the math.  I cannot find a reference, but I dubbed this process a Homodyne discriminator in my book.  A Google search...

## Re: Why complex numbers are used/introduced in electricity

Sara:  You already have plenty of inputs, and here is my take to "vulgarize" the topic.Electricity involves the relationship of charge and magnetism.  These are...

## Noise Characterization

I am concerned with stock market data.  It is described as nonstationary pink noise.  It can be reasonably represented as an exponential moving average of white...

## Re: What is cyclic frequency α?

Gardner's book costs over \$1000 and is unavailable through my library.  Do you have a more reasonable reference on the subject?

## Re: FIR filter shortening technique

If you are only interested in an amplitude approximation, why not just use an equivalent IIR filter?

## Re: IIR vs FIR filtering effectiveness in voice bandwidth

You may be getting some rounding errors that keep you from getting the brick wall response you are seeking.  Try adding a simple two sample average that will absolutely...

## Re: Determine cut-off frequency of filter from transfer function / relationship between sampling frequency and cut-off frequency

Let's keep it simple and first assume your sample rate is unity (1 sample per second, for example).  Frequency scales according to sample rate.  The correct transfer...

## Re: Zero Lag Filter

Rick:I actually just found the answer to my problem.  It turns out that micromodeler.com/dsp/# shows both the theoretical group delay as the rate change of angle...

## Re: Zero Lag Filter

Thanks Javier!I use a method similar to that of Castor-Perry, but is superior because it doesn't have the amplitude problems in the transfer response.  In my method...

## Zero Lag Filter

I was pushing poles and zeros around on micromodeler.com/dsp/# and found an interesting effect.  First, I established a simple two pole lowpass filter.  It's lag...

## Re: Lyons needs help with a "Frequency Estimation" paper.

A little off topic, but here is a way to increase the resolution of your spectrum display:  Steven Kay and Cedric Demeure, “The High-Resolution Spectrum Estimator...

## Re: Differential frequency measurement

The problem seems simple if only the sample rate is unknown.  The ratio of the two tones is constant regardless of the error induced by the sample rate.  So go...

## Re: Differential frequency measurement

I doubt if knowing the frequency difference would help you unless you have a priori knowledge of one of the tone frequencies.The highest resolution spectrum estimation...

## Re: An Oddball Electrical Engineering Question

Sorry to disagree, but you are off by at least an order of magnitude when the junction is conducting.  Although the B+ voltage may be 5V, voltage across the junction...

## Re: Estimating SNR without windowing

I found an easy solution for SNR for my particular problem.  In my case the noise tends to be broadband, and could have a pink noise spectrum.  My solution is...

## Re: Magnitude/phase vs real/imaginary

You have received a lot of similar inputs.  Here is one that has a slightly different take that may be helpful in your thought process:Consider the real part as...

## Re: Is there any way to prevent Deconvolution?

Spectrum inversion means converting a low frequency component to a high frequency component and vice-versa.  You do this by multiplying your signal by a CW "carrier"...

## Re: Is there any way to prevent Deconvolution?

Here is a guess.  Invert the spectrum.

## Re: Happy Pi Day

Can't remember PI?  Write out the first three odd digits twice, as:  113355  Now, divide the first three digits into the last three digits like you did in grade...

## Re: Instability? in Burg's method

The Burg algorithm creates a poles-only transfer response that is optimally matched to the data presented.  In essence, windowing has "no" meaning.  The output...

## Re: Instability? in Burg's method

The problem with the Burg method is that it is fairly easy to compute a pole that lies very nearly on the unit circle.  About the only solution is to reduce the...

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