### Chuck McManis (@ChuckMcM)

Jim,Matt is correct here. You "can" skip the selector (the hard bandpass) but in doing so you get a higher noise floor and spectrum folding effects from the sampling....

MEMS microphones are PDM encoded, in the case of the one you are using they appear to be noise shaping the coding to put the quantization noise at 25kHz. In nominal...

Did you know this site can use MathJax? Rewriting your comment gets:Here's the equation for 3 sinusoidal waveforms since I wrote the program for four or more...$$\sin(t*f_1)...

Are you saying you are generating a signal that you know is exactly centered in some FFT bin, and you want to zero that bin to remove it from the output?FWIW, chaining...

This is a common problem in Electronic Warfare (finding times when the Jammer is "off" so that you can transmit). Because of that, you'll find different approaches...

You are not wrong. If I understand your question you have a signal and want to know at a given time what is that signal's phase, correct? In most books this is effectively...

I suggest separating "I am new" and "want a board" :-), let me explain.It is hard to pick a board that will work without a good understanding of what you are asking...

Well I can recommend the ADALM-PLUTO SDR from ADI. Its inexpensive ($150 list $99 educational pricing) and has a bunch of educational material around DSP processing...

Like others here, a known way to do this is to get an FPGA that incorporates and ARM hard "core" and DSP blocks in its FPGA resources. The Xilinx UltraScale and...

I am going to echo everyone else's suggestion that you avoid using the TMS320C6713. Unless you are into retro hardware (which is cool in its own right, but the joy...

Does this work as an equivalent?$$ R e^{j\omega t[0]}*Re^{-jwt[-1]}= R^2 * e^{jw(t[0] - t[-1])} = R^2*e^{j\omega} $$I don't see how \( t[0] - t[1] \) becomes 1 in...

Typically the local oscillator will be generated by a frequency synthesizer. That and the mixer would be "in addition" to what you have on hand. That said, ...Given...

I suspect the part you are missing is the local oscillator. Typically in an SDR the incoming signal is "mixed" (which is a multiplication) with a sine signal that...

Glad it helped! Two resources I depend on heavily are the Mathjax "demo" page (that lets you type in code and see what it produces) https://www.mathjax.org/#demo...

I completely feel your pain! When I started I was in the same spot where I didn't know if the signal was correct, the software decoding it was correct, or the circuit...

Hmm okay, I seem to have got it, the trick is using the begin{equation*} / end{equation*} from the ams math package, and begin{align} / end{align} to align the parts.$$\begin{equation*}h_j(k) ...

Hi All,If this isn't the right place for this I apologize, I've tried a couple of other forums as well and I'm striking out.I'm trying to write Hoagenaur's equations...

Welcome Kim, sounds like you are jumping right in with both feet. It is fortunate these days that there are a lot of free tools from Octave (a MATLAB equivalent)...

Hi Groger, not trying to be unkind here but did you try typing "how to estimate a polynomial curve fit" into box at www.google.com ? If so it would have shown you...

Thanks for the response @kaz, plotting the frequency response of the taps you have gives this:Not surprisingly I've got a number of different plots where I try to...

Thanks again @gretzteam for this insight, I'm trying to understand how you got it. I started by looking at the different sequences that are generated by different...

So I've used the "unit impulse" (which is a 1.0 magnitude sample followed by zeros) to test filters, and a "unit step" (50% of the samples are 0, the remaining 50%...

Your right it does. Now nothing I've read about CIC filters talks about polyphase. That is something I need to understand, can you point me to a reference?And as...

So this is a curious one. I am continuing investigating #CIC filters now that I have run @Rick Lyons tests and proven to myself that they are now correctly implemented....

Rick,Thank you so much for your patience. You have helped connect a number of dots for me (that explanation of the diagram is brilliant).For other readers of this...

Hi Rick, [Side note: the pictures are awesome!]Your understanding is correct. Having the two pictures is also pretty cool since its easier to see how diagrammatically...

This makes a lot of sense to me, although the use of the word phase is ambiguous. I have understood differentiators to be computing the slope (i.e. the first derivative)...

Hi Rick,There is certainly something different in the differentiators :-).From your first response I use M = 1, so the differentiator is looking at X(n) and Y(n...

Rick Lyons posted an informative post about testing the implementation of your #CIC decimation filters here: Two Easy Ways to Test Multistage CIC Decimation Filters...

I'm implementing a #CIC decimation filter. I'm doing it on an microprocessor rather than in an FPGA and that means I don't "easily" get variable bit width registers....

Consider this copy for $104 (https://www.abebooks.com/servlet/BookDetailsPL?bi=...)Generally Abe Books is a much better source of old text books than Amazon.

Are you asking for the idiomatic way to do this in a DSP or just what does the process involve?If you're synthesizing the waveform you can just bump the value of...

@stephanebIn my opinion the only to metrics for a "journal" are credibility and the ability to track down citations to papers in that journal.Sadly credibility has...

Assuming you have the spectrum in complex form you band pass filter out the 1700 Hz, multiple the result by a .5 Hz complex sinusoid and add the result back into...

I am always a bit annoyed by "pay to publish" journals. Especially if that journal then charges extortionately for people to get copies of the papers. Given that...

Actually the Teensy 4 is pretty reasonable for this. I've got the Digilent I2S PMOD board which can do 192 kSPS in stereo.

Hi Sharan, make your data complex with the real component being MAXVAL and your quadrature component being randomized. That will spread the signal across the entire...

Hi Chalil, It is helpful, thank you. In this particular case I am relying on the 32 bit nature of the registers to deal with overflow.The math question though is...

Per Achilles comment, the FFT is always complex, even if you feed it a purely real signal. When you combine that with the understanding that a complex signal that...

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