## How to perform efficient sampling

Started by in comp.dsp16 years ago 11 replies

Why use multiple sampling rates? The most important reason is for efficiency of calculation and/or memory. But what is the lowest sampling rate...

Why use multiple sampling rates? The most important reason is for efficiency of calculation and/or memory. But what is the lowest sampling rate possible? Well, the Nyquist theorem tells us that the sampling rate must be at least twice the bandwidth of the signal. Therefore, for maximum efficiency, you would like to do DSP processing at a rate which is a small multiple of the signal bandwidth. ...

## Complex Sampling Techniques

Started by in comp.dsp15 years ago 25 replies

Hello out there, I am confused about hardware implementation of complex sampling. Can I just set up two ADCs sampling at the same rate, but...

Hello out there, I am confused about hardware implementation of complex sampling. Can I just set up two ADCs sampling at the same rate, but with their clock signals 90 degrees out of phase, or do I actually need to multiply my input signal by a sine-wave? I assume that by sampling with 2 ADCs with out-of-phase clocks, this is the equivalent of multiplying by complex sine wave which is in p...

## CAUTION! was "What is the advantage on high-sampling rate ?"

Started by in comp.dsp17 years ago 150 replies

Hi Guys, in a recent thread, mention was made of a "Sampling" paper by Dan Lavry. At the following web...

Hi Guys, in a recent thread, mention was made of a "Sampling" paper by Dan Lavry. At the following web site http://www.lavryengineering.com/pdfs/sample.pdf you can see Dan's 1997 paper: "Sampling, Oversampling, Imaging and Aliasing - a basic tutorial". I recommend caution if you decide to read that paper. In the second paragraph Dan wrote: *** Sampling theory *** ...

## Sampling in short bursts?

Started by in comp.dsp16 years ago 1 reply

Hello I?m wondering what rules applies if I?m sampling a signal in short bursts? Lets say I want to sample a level and I do that by...

Hello I?m wondering what rules applies if I?m sampling a signal in short bursts? Lets say I want to sample a level and I do that by sampling 10 sample points at 1 ?s apart. Then I calculate I mean value of these 10 points. The sampling frequency in the bursts are 1 MHz. Should I calculate my antialias filter by that value (fN = 500 kHz) ?

## Fundamental Sampling Theory and Real-time Constraints

Started by in comp.dsp9 years ago 18 replies

Hi everyone, I'm new to the arena of DSP and have arrived at a bit of a sampling-based conundrum. I'm wondering if anyone here can help me out...

Hi everyone, I'm new to the arena of DSP and have arrived at a bit of a sampling-based conundrum. I'm wondering if anyone here can help me out with possible solutions, or can simply set my understanding straight. I have an application where my signal of interest has a bandwidth of 500Hz. At Nyquist, I'd be sampling at 1 kHz. Of course, I could oversample by this by some factor and filter it ...

## Sampling a gyro and alias filtering?

Started by in comp.dsp15 years ago 7 replies

I want to sample a gyro and then integrate the angular rate to get the angle. When sampling the signal from the gyro, how important is it...

I want to sample a gyro and then integrate the angular rate to get the angle. When sampling the signal from the gyro, how important is it to filter away frequencies higher than half the sampling rate? I should have at least enough attenuation at the sampling frequency (Fs) so that a signal at Fs Hz doesn?t alias back to DC (0Hz). But what bout the other frequencies that alias, ca...

## ADC Sampling with variable frequency and Nyquist?

Started by in comp.dsp5 years ago 7 replies

I wonder if I can sample a signal using an ADC with variable sampling frequency. Lets say the signal bandwidth is 10 MHz at baseband. In order...

I wonder if I can sample a signal using an ADC with variable sampling frequency. Lets say the signal bandwidth is 10 MHz at baseband. In order to reconstruct the signal, the ADC sampling frequency must be > 20 MHz. What if I use a sampling frequency that varies between 19.9 MHz and 20.1 MHz? What does the Nyquist sampling theorem tells us about this case? Are there applications that actua

## samples per symbol Vs sampling rate - Can they be used interchangeably?

Started by in comp.dsp11 years ago 4 replies

Hi, Do samples per symbol and sampling rate convey the same message? I know what sampling rate is but why samples per symbol is used in...

Hi, Do samples per symbol and sampling rate convey the same message? I know what sampling rate is but why samples per symbol is used in certain cases instead of sampling rate? I think that samples per symbol is used in systems where the signal is processed at baseband whereas, sampling rate is used for systems where processing is done at IF.

## cutoff and sampling frequency

Started by in comp.dsp13 years ago 14 replies

Hai, Basically i am little bit confused with FIR filter cutoff frequency and sampling frequency relation....Both the terms are very...

Hai, Basically i am little bit confused with FIR filter cutoff frequency and sampling frequency relation....Both the terms are very much familier to me separately but i dont know how to relate each other?? Few standard sampling frequencies for audio applications are 8,44.1,48,96,192Khz...For this sampling frequencies wat should be the minimum cutoff frequency for LP,HP,BP,BR FIR filter.....

## "Quadrature signals : Complex, But not complicated" by Richard Lyons

Started by in comp.dsp18 years ago 5 replies

Hy, I recently read this good article of Richard Lyons but there is something i can not understand. Does someone could help me understand...

Hy, I recently read this good article of Richard Lyons but there is something i can not understand. Does someone could help me understand this difficulty ? It it says : "Each A/D converter operates at HALF the sampling rate of standard real-sampling" !!! How does it work ? It seems that using half the sampling rate of standard real-sampling, we obtain the same frequency definitio...

## Regarding sampling.

Started by in comp.dsp15 years ago 39 replies

Dear Group, I have an elementary question. If a sine-wave is sampled such that the samples fall at the times when the value of the wave is...

Dear Group, I have an elementary question. If a sine-wave is sampled such that the samples fall at the times when the value of the wave is zero (meaning at 0 and pi). The sampling frequency thus is twice the frquency of the wave. Is this proper sampling ? How can we reconstruct such a signal ? Of course the power of the signal is non-zero. Is that sufficient to prove that the input sign...

## Nyquist Sampling

Started by in comp.dsp14 years ago 4 replies

I'd like to ask a couple very basic questions. Being hands-on rather than mathematically-focused I'm trying to visualize sampling in a project...

I'd like to ask a couple very basic questions. Being hands-on rather than mathematically-focused I'm trying to visualize sampling in a project I'm planning to start. 1. By sampling say a 3.1 kHz band-limited voice channel at the Nyquist rate am I guaranteed to capture *all* the information in the channel? Is nothing lost (ignoring ADC resolution)? More to the point: To know what the ...

## Beginner Question - Discrete Fourier Series and sampling

Started by in comp.dsp13 years ago 1 reply

Given I have an input sequence [ 1 0 1 0 1 0 1 0 ], the DFS is x[n] = 0.5 + 0.5*exp(j*pi*n). The sampling (Ts) is 100 secs. Am I correct in...

Given I have an input sequence [ 1 0 1 0 1 0 1 0 ], the DFS is x[n] = 0.5 + 0.5*exp(j*pi*n). The sampling (Ts) is 100 secs. Am I correct in saying that the spectral coefficient 0.5 at pi is equivalent to saying the DFS has a 0.5 peak every 200 secs? My reasoning is between adjacent x[n] samples a time Ts has passed which corresponds to 2*pi of the sampling period. Therefore, half, i.e....

## Sampling: What Nyquist Didn't Say, and What to Do About It

Started by in comp.dsp11 years ago 135 replies

I know there's a few people out there who actually read the papers that I post on my web site. I also know that the papers have gotten a bit...

I know there's a few people out there who actually read the papers that I post on my web site. I also know that the papers have gotten a bit ragged, and that I haven't been maintaining them. So here: I've made a start. http://www.wescottdesign.com/articles/Sampling/sampling.pdf My intent (with apologies to all of you with dial-up), is to convert the ratty HTML documents to pdf as...

## Aliasing and Sampling Prog question

Started by in comp.dsp16 years ago 2 replies

I want to show aliasing and sampling graphically with spectra by using LabVIEW (or similar).Here is what I am doing I have a ficticious...

I want to show aliasing and sampling graphically with spectra by using LabVIEW (or similar).Here is what I am doing I have a ficticious sampling freq which is my 'analogue' signal - lets say I make it 500MHz. I then pass white noise through a narrowband filter centred at say 10.7MHz bandwidth 200kHz. I take the FFT and see the spectrum and its negative image - no problem. I add a sine w...

## non uniform sampling and interpolation

Started by in comp.dsp15 years ago 1 reply

Hello, In another post I asked about interpolation and sampling and I got some good response. After reading them, I am now interested in...

Hello, In another post I asked about interpolation and sampling and I got some good response. After reading them, I am now interested in non uniform sampling and interpolation. What I am interested is to solve following type of problems: Assuming I have a 1D signal that the value of it is known at n=[1 3 4 6 9 10 15 19]. I want to calculate the values at other points {n=[0 2...

## Simulation of Sampling Clock Offset

Started by in comp.dsp14 years ago 11 replies

I am simulationg an OFDM system in Matlab for which I need to generate a sampling clock offset in my transmitted signal so that I can write an...

I am simulationg an OFDM system in Matlab for which I need to generate a sampling clock offset in my transmitted signal so that I can write an algorithm at the receiver to correct it. Can any body tell me how to generate a sampling clock offset in the Transmitted signal. I think I have to use interp1 function but I dont have a clear idea. Sampling Clock offset should be a linear function o...

## FFT length and sampling frequency relationship

Started by in comp.dsp15 years ago 3 replies

Hi All, i was going through DSP book by proakis, there i came across the following realted to for which sampling frequency what is the...

Hi All, i was going through DSP book by proakis, there i came across the following realted to for which sampling frequency what is the fft lenght to be used like, Sampling Freq FFT Length 8KHz 256 22KHz 512 32KHz 1024 44.1/48KHz 2048 My query is on what...

## Optimal sampling for damped sinusoid

Started by in comp.dsp15 years ago 7 replies

I am measuring a transient oscillating signal and have been wondering about the optimal sampling scheme to determine the decay and...

I am measuring a transient oscillating signal and have been wondering about the optimal sampling scheme to determine the decay and frequency. The model is S = A.exp(-Bt).sin(Ct) and I can sample about 5 points before the signal has decayed to zero. I have reasonable estimates for C so I have been sampling at the peaks and troughs, ie. when the sin term is approximately +/- 1. It seems to work...

## G.729 with different sampling rates?

Started by in comp.dsp17 years ago 12 replies

I'm trying to understand G.729. The only compression algorithm I've coded before is ADPCM, and it wasn't keyed to a certain sampling rate - that...

I'm trying to understand G.729. The only compression algorithm I've coded before is ADPCM, and it wasn't keyed to a certain sampling rate - that is, it would be just as happy with 8100 samples per second or 7900 samples per second as it would have been with 8000, just the quality would be slightly higher or lower. With G.729, all the documentation refers to a sampling rate of 8 KHz. Is it ...