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ADC and undersampling

Hello, As a result of a measurement I obtain a bandlimited signal centered at 144 kHz (12kHz Bandwidth). I was planning to use undersampling (Fs=192kHz) to fold this signal to 48kHz in the digital domain. I am having a difficulty to find an ADC for this purpose. The only ADCs I could find (I...

Undersampling and Quadrature Sampling ?

Hi, I would like to undersample a 70 MHz IF signal at a sampling frequency of 55 MS/s. So this undersampling method creates a 15 MHz IF2 whith 55 MS/s. Now I would like to donwconverter this 15 MHz IF2 to baseband (0 IF) with quadrature sampling, so I need to generate a sinus at 60 MS/s and...

Undersampling IF software

Hi, I'm looking for a software to compute the frequency sampling for undersampling an IF radio spectrum. For example, if I have a IF of 455 kHz with 80 kHz bandwith, I can sample at 200 kHz and the second IF would be 55 kHz. I have try to compute with software designed for RF mixer but it...

digital ultrasonic demodulator by undersampling

Hi! I want to make an ultrasonic leak detector. Generally, they consist mainly of an ultrasonic transducer and an analog demodulator with a carrier of 40Khz which they enable to hear and to measure an audio signal from 0 to 1.5 or 3Khz. How I can make that digitally? I'm thinking about to make...

Re: Digitizing advice

If you undersample, then in fact you do need an analog hold circuit that is fast enough for the total carrier frequency (2G) - but your ADC need only be fast enough for the band you are in fact measuring. This is because when undersampling, once the signal is held (the expensive part) you have...

Beginner's question on undersampling and aliasing

Hi all, I am a newbie to DSP. I have a huge number of data samples that I want to perform FFT on. But due to the enormous amount of the data samples, I'd like to use only 1M samples and perform FFT. I know that this is severe undersampling and that it does not satisfy the Nyquist rate. But all...

Re: frequency shifting (compressing?)

kreuters wrote: > am i correct in thinking that if i band pass filtered the stream between > 30 - 80 kHz, then took every eighth sample the audio would be aliased into > the audible range? No, undersampling is not the nature of your problem. You wish to scale one base band down to f...

AM receiver - utilising bandpass undersampling and quadrature mixing

Hi, I am new to the whole DSP thing (very new) and have a question regarding the use of undersampling and quadrature mixing to demodulate a signal in a given range. I have been trying to research the topic but have not been getting very far. I understand how the bandpass signal can be undersam...

Re: Spatial Aliasing in Beamformers

"Tom" wrote in message news: ... > I have been reasing a paper that says that for acoustic beamformers (I > suppose the same applies to EM beamformers), the distance between > microphones must be > > d > where Lmin is the minimum wavelength.For 8kHz sampling frequency this makes ...

Undersampling to measure phase.

I have two 70 MHz signals (one a clean reference sine wave, the other a lot less so), but wish to find the phase difference between these two signals. The A/D, the AD9226: http://www.analog.com/UploadedFiles/Data_Sheets/394988775AD9226_b.pdf has a maximum sampling rate of 65 MSPS, but is...

Effect of OverSampling

I'm new to DSP and also this group. My question is "what can be the negative effect of Oversamling in terms of Destortion in original signal?". As in undersampling two spectrum are overlapped and we may not be able to get original signal.. is that any kind of effect in oversampling? ...

Re: Undersampling

On Sat, 14 Jan 2006 01:21:15 +0000, Vladimir Vassilevsky wrote: Cool. Thanks, Vladimir. You mentioned IC solutions that have the downsampling built in. Do you have any specific suggestions that you believe would be a good choice for my problem space? -- Regards, Bob Monsen "I...

Undersampling of a clean carrier

Hi, I have just been doing some test and I noticed a concerning problem that I may be having with the undersampling design (for FM demod). I basically set up my board so that the adc input (which is clocked at 80MHz) feeds directly into a DAC also clocked at 80MHz. If I put a 20MHz tone...

Re: Undersampled Data

Hello, I think this is not so much about signal processing but about statistics: When you say you are "undersampling" I agree: It is not possible to reconstruct the actual "waveform" from the samples without loss of information. Still, statistics will be able to extract useful information fro...

Re: Nyquist Didn't Say That

Jerry Avins wrote: > In theory only. To resolve a signal at 2.00000X would require 1,000,000 > seconds. (OK: maybe only 150 hours.) 150 hours? Why? > Right or wrong, that's what I meant.* What's more, to resolve Fs/2 - 10 > Hz, you also need to to sample for a time in the order of 1...

An intriguing story about undersampling

Read this astonishing story at http://spazioscuola.altervista.org/UndersamplingAR/UndersamplingAR.htm Here it is an excerpt: A STORY ABOUT UNDERSAMPLING by Angelo Ricotta - Rome, Italy a.ricotta@isac.cnr.it ITALIAN VERSION In the article "Turning Nyquist upside down by undersampl...

Undersampling Question

Dear folks, I was wondering if you could help me with this problem. I have an accelerometer with a resonance of say 15kHz. I need to do envelope detection of this (acts a bit like AM with 15kHz as the 'carrier'). The bandwidth of this signal is lets say 4kHz so that we bandlimit from 13kHz up...

Re: I'm confused ;) was[Re: ADC limitations for bandpass/IF sampling]

Hello Bhaskar, > No - as Jerry has already explained, one of the important things that > limits undersampling is the BW of the front-end of the ADC. Usually the > analog front-end of an ADC will be several tens of times (say 10x) the max > sampling rate it can support. > If the ADC ...

Who attended Embedded Sys Conference in San Francisco

Hi Guys, I'm wondering if any of you attended the Embedded Systems Conference (also called "electronicaUSA") in San Francisco last month. I have a question about a paper that may be on the CD distributed at the conference. The lecture paper that interests me is titled: "Unde...

Re: Problem in Sampling

Sai Kumar wrote: > Dear All, > > > I have one problem in real time signal processing. My signal frequency is > 4000Hz and the sampling frequency is 8000Hz. Actually it should be more than > 8KHz. > > Becasue of that i am loosing the zero resting points of the sampled signal. > ...

Re: Interchanging of filtering and decimation operations

On Apr 27, 12:23 pm, Jerry Avins wrote: > It needs to be clear that > one can't decimate first and filter later. > Hi Jerry, I think there may be times where you can decimate first and filter. If the significant components of the signal don't alias to be on top of one another, a pers...

Re: Total phase of a sum of complex numbers

Rune Allnor wrote: ... > I'm testing out various ideas that rely on the unwrapped phase. > The problem is that the various unwrapping schemes apparently > have their deficiencies, so I'd like a synthetic reference where > I know the "true" answer (total phase), and then test the un...

Image-reject IF downmixing

When digitally mixing an IF down to baseband, one is left with a spectrum that consists of the baseband (Fif - Fmix = 0Hz) and an image (Fif + Fmix). If the IF is greater than the Nyquist freq, the image will wrap back into the first Nyquist zone (0 to Fn). Normally the next step in demodulati...

Re: Equivalent time sampling

On Nov 5, 9:54=A0am, "alexgaas" wrote: > Hi guys! > Does anyone know any algorithm used in digital storage oscilloscope? > I know that many DSOs use equivalent time sampling technique but what > about the digital hardware (or algorithms) to filter and reconstruct the > signal?? > If a...

Real time FFT voice processing...why wont it work?

Hello all, I am curious why such a system does NOT work. I am using a 16-bit fixed-point DSP chip: voice1 -> ADC -> DSP -> DAC -> voice2 I collect an array of samples and pass them through an FFT then an inverse FFT. The sample size is 256 but obviously, that can be changed. The FF...

undersampling and FFTW

Hello, I have a problem with my fftw complex transform (1d) when I want to undersample my signal. I start with initial signal (Dimension 16384points), and get the FFT of this signal in complex with fftw_plan_dft_1d (result is a 16384points dimension too). This signal has 128 first non-zero va...

Undersampling

I am on a team developing a system that will record and process large (1 GHz) bandwidth pulses. Doing some research I have came across some one that suggested sampling in the 2nd nyquist zone, for two main reasons. Sampling the signal at a higher frequency makes our analog front end much bette...

Re: Possibly unrelated questions

Richard Owlett wrote: > glen herrmannsfeldt wrote: > > Jerry Avins wrote: > > (snip) > > > > > The question is whether imaginary numbers and negative frequencies > > > are inherent qualities of the real world, or whether they are > > > scaffolding for the simplified mathematics that ...

expected spectrum of aliased BW limited white noise

I'm fairly new to DSP and am trying to see the effect of undersampling on bandwidth limited white noise in Simulink. I took the bandwidth limited white noise source (set the BW to 1kHz), put it through a zero order hold with Sampling rate set to initally 5kHz and the output of this is connected t...

Re: Digital synthesis of Quadrature, please help

Graeme Zimmer wrote: > Greetings, > > I have a nice little DSP radio working, see > http://members.wideband.net.au/gzimmer/DSP_Rx/SimpleRX.html > > It uses two mixers to develop the quadrature data streams. > > I figured that I could eliminate the quadrature mixers, > if I could ...

Re: Guidance in determining phase difference between two sinusoidal signals needed

Hello Jerry, Imagine a thing you can get is an old oscilloscope where the timebase is unknown. Imagine you want to know the phase between two signals. Hence you are an engineer knowing the phase without knowing the delay ... What I want to say: Possibly there are algorithms calculating phase ...

Re: bypassing antialiasing filter of TLV320AIC23

murselonder wrote in news:1181921715.561258.174770 @m36g2000hse.googlegroups.com: > Hello, > > I have been using C6713 DSK. My question is; Is there antialiasing > filter in front of AIC23 codec of DSK. If yes, can bypass (omit, > cancel) it? > > In other words, can I sample o...

Undersampling: Specifying Clock Jitter?

Hi all, I'm basically trying to design a power spectrum analyser that can capture channels with a bandwidth of 100 MHz. I select either 10 MHz - 110 Mhz or 135 MHz - 235 MHz and am sampling with a 250 MHz ADC. The ADC has a full power bandwidth of 1 GHz and has 12 bits. My goal is to be abl...

basic DSP example & my confusion

Hi, I'm trying to pick up some more DSP understanding and I've been using Richard Lyon's book, Understanding Digital Signal Processing. Its been very helpful thus far, but there's one example that's driving me crazy. I've bounced this off another couple people here, but they seem confused as well. ...

Re: high speed dsp

"Tim Wescott" wrote in message news:11efan1g8jpcm10@corp.supernews.com... > Chi Chian wrote: > > > i was thinking of a high speed (~250Msps) high resolution > > (say> 15bits) ADC. is there such a device in the market? > > how abt multiplexing a few slower but high resolution > >...

Re: Undersampling of a clean carrier

"Paul Solomon" wrote in message news:431e07ae$1@dnews.tpgi.com.au... > > "Thomas Magma" wrote in message > news:dXiTe.402841$5V4.32336@pd7tw3no... > > > > "Paul Solomon" wrote in message > > news:4316590d@dnews.tpgi.com.au... > > > Hi, > > > > > > I have just been doin...

Re: FIR Filter limitation (or not?)

1) Frequencies above Fs/2 will appear, aliased to other frequencies. Uusally an antialias filter is used - this MUST be analog, and should filter out all frequencies above Fs/2 so that they are not a problem. But in undersampling, you can have a high frequency signal (ie above Fs/2) that alias...

Re: Why TI makes no further efforts in floating point DSP?

Randy Yates wrote in news:m363ta8je4.fsf@ieee.org: > Al Clark writes: > > [...] > > SHARC DSP > > Hey Al, > > Speaking of SHARCs, have you completed your new SHARC design > with the integrated high speed ADCs? Can you tell us more about > this board? SURE, Shameless c...

Re: OT: Undersampled Humming Bird Video.

Symon wrote: > Hi All, > If anyone's interested, I captured a video yesterday of a humming bird on > our feeder outside our apartment in Los Gatos, CA. I'm quite pleased with > it! You can download it from > http://home.comcast.net/~symon_brewer/Motion_16.avi . It's a 15 Mbyte AVI >...

Re: Complex mixer

ma wrote: > Hello, > > I learned that when a signal is multiplied by an IQ signal, the > signal can be down sampled by 2. Yes, no, maybe. Yes, if the conditions are right. No, if you're too simpleminded about it. Maybe you can downsample even more. > So assume t...