## Forums

## Troubles in simulating sharp edges

inHi, I am fighting this problem for two days now: I want to simulate a passive mixer (50% and 25% Duty Cycle) which is basically a switch...

Hi, I am fighting this problem for two days now: I want to simulate a passive mixer (50% and 25% Duty Cycle) which is basically a switch and hence can be modeled by multiplying the input with a rectangular waveform (or less harmonics). Suppose I have a clean sinusoidal LO x0 = sin(2*pi*100MHz*t). If I have sign(x0) (or alternatively Zero-Order-Hold with 2 samples per period) then I ge...

## How to convert from PDM to PCM ?

inI have a client who is using a MEMS microphone (SPM1423HM4H-B, 3.125MSPS). The output of the microphone is a PDM...

I have a client who is using a MEMS microphone (SPM1423HM4H-B, 3.125MSPS). The output of the microphone is a PDM signal. Datasheet: http://media.digikey.com/pdf/Data%20Sheets/Knowles%20Acoustics%20PDFs/SPM1423HM4H-B.pdf In the client's test setup an emitter emits an acoustic signal. The emitted signal has frequency components around 40kHz. When I reviewed the client's setup, I noticed a c...

## PID controller in a robotic sailboat

inI'm a long time lurker, here because occasionally the math is interesting. But recently, I got a chance to do some embedded programming. I...

I'm a long time lurker, here because occasionally the math is interesting. But recently, I got a chance to do some embedded programming. I thank Tim Wescott for his intro to PID controllers. I'll get to that bit, but first there's some background material. There's a program at Community Boating in Boston, Mass. which since at least 2013 has let high school students design software for con...

## Special offer

Dear All, This is a limited time (genuine) offer for a free license of FFT Properties...

Dear All, This is a limited time (genuine) offer for a free license of FFT Properties v6.1: https://www.dewresearch.com/products/fft-properties Anybody who is kind enough to submit a step by step reproducable bug report to support@dewresearch.com until Sunday 19th of November 2017 will receive a free license. Common sense applicable, no missing features etc... Wish you happy day at wo...

## FW: Discrete Fourier Transform (DFT) viewer and/or file format

Dan Hitt posted the following on the Debian user list. [https://lists.debian.org/debian-user/2017/11/msg00444.html]. I suggested he ask on...

Dan Hitt posted the following on the Debian user list. [https://lists.debian.org/debian-user/2017/11/msg00444.html]. I suggested he ask on comp.dsp . > I have some DFTs that i wish to inspect. (Apparently DFT is a common > acronym, but here i mean Discrete Fourier Transform. And properly > speaking it doesn't make sense to inspect a transform, but only to > inspect transformed data, but

## wow. it starting to look like USENET is getting pretty dead.

inthis used to be a very active newsgroup. nothing happening since Oct 17 and now it's Nov 2. sorta gets eclipsed by Stack Exchange (which...

this used to be a very active newsgroup. nothing happening since Oct 17 and now it's Nov 2. sorta gets eclipsed by Stack Exchange (which allows for formatting math equations and pasting in graphics). r.i.p. comp.dsp i guess we all die sometime or 'nother. r b-j

## The significance of Upsampling at QPSK transmitter ?

inHello, I would like to ask why would we need the upsampling process for bits in Transmitter side? We do upsample then pass it through matched...

Hello, I would like to ask why would we need the upsampling process for bits in Transmitter side? We do upsample then pass it through matched filter then modulate it, but why and how to choose the upsampling factor ? To be more precise, what would happen if we pass the bits through the matched filter without upsampling? This is in QPSK transmitter and can be generalized for all other digi...

## Need Help

inCan anybody provide me the solution for following problem. It will be great help. Adaptive filter with variable update equation: Develop...

Can anybody provide me the solution for following problem. It will be great help. Adaptive filter with variable update equation: Develop a stochastic gradient adap-tive ï¬lter that attempts to minimize the following cost function: J(n)=E{|e^2(n)|}. e(n) =1 Discuss the possible advantages and disadvantages of your algorith

## Low-overhead high quality sine wave generation

inResonant filters are often used for this purpose, but with a remark that they need some way of amplitude control, because the numeric errors can...

Resonant filters are often used for this purpose, but with a remark that they need some way of amplitude control, because the numeric errors can make it rise without control (gain > 1) or decay to 0 (gain < 1). I don't know about you, but for me it was a great surprise to discover that for certain "magic" values of amplitude the error integrated over the entire period is *exactly* 0, which

## Good phase detectors for low-frequency software PLLs

inI am simulating a software PLL intended to lock to mains, which here is 50Hz. The problem is, as usual, in selecting a good phase detector. For...

I am simulating a software PLL intended to lock to mains, which here is 50Hz. The problem is, as usual, in selecting a good phase detector. For high frequency application the JK/D edge-sensitive digital phase detectors work very well, but for 50Hz the number of edges per second is low, hence the covergence is slow (or with significant ringing). OTOH, the basic multiplying detector is real-ti...

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