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## The zero-order hold

inText books are filled with info on the DAC zero order hold and it appears on the internet everywhere. Basically its TF is (1-exp(-sT))/s where T i...

Text books are filled with info on the DAC zero order hold and it appears on the internet everywhere. Basically its TF is (1-exp(-sT))/s where T i sampling interval. Usually they take 1-z^-1 in cascade with the system transfer function and 1/s is merged into the system. If the system is G(s) then they convert (1/s)G(s) to the z domain. Doesn't this seem a little old fashioned nowada

## Minimum ADC Sampling Rate / Symbol Rate for a PSK Modem with Time and Carrier Recovery.

inDear DSP Gurus, I have to demodulate a 50 MHz wide (3 dB bandwidth) OQPSK modulates Signal. The Signal properties are: OQPSK Modulated AWGN...

Dear DSP Gurus, I have to demodulate a 50 MHz wide (3 dB bandwidth) OQPSK modulates Signal. The Signal properties are: OQPSK Modulated AWGN channel Has Doppler Shift (5 KHz/sec max) Pulse shaping filtered (0.35) Viterbi+RS The HW I am using is: Zero IF Receiver ADC on I&Q channels (12 bit output) Has a signal processor (Output is IQ corrected,DC Removed,AGC) The Output is: I ...

## Differences between laplace transform, z transform and fourier transform

inHi All, I have studied three diff kinds of transforms, The laplace transform, the z transform and the fourier transform. As per my...

Hi All, I have studied three diff kinds of transforms, The laplace transform, the z transform and the fourier transform. As per my understanding the usage of the above transforms are: Laplace Transforms are used primarily in continuous signal studies, more so in realizing the analog circuit equivalent and is widely used in the study of transient behaviors of systems. The Z transform is the ...

## CIC Decimation Filter "zero crossing" distortion

inHi, I am designing a simple decimation filter, with decimation rate at 5 (1st stage) and 20 (2nd stage). N=2 and 3 for each stage. Bin=1....

Hi, I am designing a simple decimation filter, with decimation rate at 5 (1st stage) and 20 (2nd stage). N=2 and 3 for each stage. Bin=1. Bout=16. Input Sampling frequency at 50 KHz and output at 500 Hz. The fixed point matlab simulation (2's complement) shows that with Sinewave input at 5Hz, there are a few "flat" "zero" crossing points in each sinewave cycle. I check t

## OT: Who invented the airfoil?

inHi all. This is one of those questions that just popped into my mind last night: Who invented / discovered the airfoil? Like in...

Hi all. This is one of those questions that just popped into my mind last night: Who invented / discovered the airfoil? Like in aviation history. I know the Montgolfiers discovered the balloon, the Wright did the first powered flight and so on, but who was the first to describe the airforil as a component for 'heavier-than-air' flight? Lilienthal used devices very similar to what we t...

## New Signal Processing with LabVIEW for measurement blog

inCheck out my new blog, "LabVIEW DSP" dedicated to sharing insight regarding signal processing in National Instruments LabVIEW as it relates to...

Check out my new blog, "LabVIEW DSP" dedicated to sharing insight regarding signal processing in National Instruments LabVIEW as it relates to measurement. My first two posts cover accuracy / confidence intervals and spectral averaging. Enjoy! http://www.labviewdsp.com

## daily quiz

inFrom a known genre of puzzles - "what's my hat?" - appropriate for this group, as it involves information, if not theory - Three men,...

From a known genre of puzzles - "what's my hat?" - appropriate for this group, as it involves information, if not theory - Three men, blindfolded, each wear a hat. H or T is written on each, according to coin tosses. The blindfolds are removed. Each sees the others' labels, but not his own. All must simultaneously, and immediately, guess his own label, or pass. No communicat...

## OT: An Engineering Program Manager Joke

inHi, Things have been pretty quiet hear for the last few days. Having nothing more useful to post, here's a joke about Program...

Hi, Things have been pretty quiet hear for the last few days. Having nothing more useful to post, here's a joke about Program Managers; A program manager has been working his team extra hard and as a small reward offers to take two of the engineers out to lunch. Walking to the restaurant they trip over a magic lamp and out pops a genie offering them each one wish...

## Multiple ADCs and aliasing

inI have two 1MHz ADCs and would like to interleave them by a half of the sampling cycle in order to get a single ADC with effective sampling...

I have two 1MHz ADCs and would like to interleave them by a half of the sampling cycle in order to get a single ADC with effective sampling frequency of 2MHz (I want to oversample the signal by as much as possible). But the aliasing properties of the data stream will be as if the signal was sampled at 1MHz because the ADCs are independent blocks and don't influence each other, right? Bes...

## Is 'Bessel' digital lowpass filter standard?

inHi, I'm trying to design a simple IIR lowpass filter with the following specs: fs = 2.4kHz fc = 150Hz order = 3 or 4 The most important...

Hi, I'm trying to design a simple IIR lowpass filter with the following specs: fs = 2.4kHz fc = 150Hz order = 3 or 4 The most important aspect is that the ringing (overshoot) shouldn't be higher than about 3%. When using a 3rd order Butterworth, I get about 9% overshoot, which is too much. Someone hinted my that a Bessel filter would be better suited. This program is a good start http:...

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