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Discussion Groups > Decimation

Comp.dsp is a worldwide Usenet news group that is used to discuss various aspects of digital signal processing.

We found 605 threads matching "decimation"

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The most relevant threads are listed first

decimation filter problems

fyzkydmn - 2011-03-30 12:54:00
Hi, I have 2 questions about decimation filter for a SD ADC. Firstly, how is the relationship between SNR and stopband attenuation for decimation filter. For example if I have 14 bits output of the decimation filter, SNR=(6.02*N+1.76)=86 db, so will I choose stopband attenuation > 86 db for decim...decimation filter problems

multirate implementation on fix point DSP and efficiency

domistep - 2005-09-12 07:41:00
Hye, I have a question to try to find a way to improve my processing. I use a multirate filter with decimation. There is a decimation by 40. One FIr is used then decimation, and the 1 IIR with decimation, then a second IIR with decimation, then again oner IIR and decimation and at last one F...multirate implementation on fix point DSP and efficiency

i'm sorry...what's decimation?

c1910 - 2007-06-12 08:50:00
hi! i'm sorry what is decimation? yesterday, i found a block diagram of digital signal processing for demodulate AM signal... and there is a decimation process after the balance modulator... i don't understand the function of decimation process... please, help me... thank you... -c1910-...i'm sorry...what's decimation?

Question about Z transform of decimation

Jeff - 2004-09-06 17:48:00
Hi, I am learning about digital decimation. The problem is like this: Z-transform of input sequence and filter aree X(z), H(z) respectively. After the filter H(z), there is a 2 decimation. From one book talking about decimation, it says the Z-transform of output sequence after decimation is: ...Question about Z transform of decimation

Decimation for demodulation

c1910 - 2007-06-14 05:57:00
hi! i want to demodulate AM signal with DSP...i found an article that says like this : demodulator is illustrated as decimation integration filter. It includes a multiplier portion and an integration/decimation portion. so can we demodulate AM using decimation method? and what is decimatio...Decimation for demodulation

i'm sorry...what's decimation?

c1910 - 2007-06-12 08:41:00
hi! what is decimation? can everybody give me an example? or the definition? or what is the function? thanks, coz i don't understand the decimation?! ...i'm sorry...what's decimation?

Decimation design

seb - 2004-03-27 16:55:00
Hello, I am looking for good advices about my design. I am working with an ADC which work beetween 1kHz and 2kHz but the application need data sampled beetween 10 Hz and 2 kHz. So i decide to make decimation in order to get the sample frequence beetween 10Hz and 1 kHz. But in order to do it...Decimation design

Multirate Filter

Vladimir Vassilevsky - 2006-08-25 10:26:00
Rick Lyons wrote: > It took me a while to find the darned post of mine. > My post was: > > From: (Rick Lyons) > Subject: Re: Multirate filter design > Date: Tue, 11 Jul 2006 10:45:44 GMT > I remember reading (somewhere) that it is *VERY* > difficu...Multirate Filter

Question for bit number decision of decimation filter's output

pcchen - 2009-05-06 11:06:00
Hi All, I'm a HW engineer and need to design decimation filter for sigma-delta ADC. After reading some articles and discussion from internet, I knew decimation filter has 2 major function, downsample and 1-bit to multi-bit data conversion. As all replies for for bit number decision of decimation filter's output

CIC decimation filter

sowmini - 2007-10-05 07:53:00
I need to implement a decimation filter( using CIC structure )in C. I have created integrator block,another block for decimation and finally a third block for comb structure and cascaded them in that order.But the final frequency response doesnot match the theoretical graph.I have used 2's complime...CIC decimation filter

Sigma Delta - Decimation Filter Design

analog_fever - 2010-06-29 12:03:00
I am designing filter to do decimation at the output of a Sigma Delta modulator. Here is the spec - Sampling frequency - Fs - 1.4MHz Decimation factor - D - 100 Input - 3 bits Output resolution - 13 bits. The filter, and the modulator are reset every 100 clock cycles. I tried using a CI...Sigma Delta - Decimation Filter Design

Decimation / downsampling

pardon_232000 - 2004-02-14 13:28:00
Hello, I have problem puting the rigth name on the rigth thing: --> In "Discrete-time signal processing" of Oppenheim and schafer : "In general, the operation of reducing the sampling rate (including any prefiltering) will be called downsampling" section 4.6.1 --> In "An overview of sig...Decimation / downsampling

Decimation (CIC) filter in VHDL

Ahmad - 2003-08-27 15:27:00
Hi all, I am currently in the process of designing a decimation filter for a 16bit Sigma Delta ADC. I suspect it will be a CIC filter followed by a FIR filter. I am facing great difficulty understanding such filter, as my experience in usually with analog circuits, and not DSP. My ques...Decimation (CIC) filter in VHDL

decimation by dropping two samples

sudarshan_onkar - 2011-04-26 03:08:00
Hi All, I was analyzing a decimation scheme where two samples are dropped alternatively . 0,1 are picked 2,3 are dropped , 4,5 are picked and 6 and 7 are dropped and so on. I have never seen such a decimation scheme . I would like to know whats the advantage of the this scheme. An...decimation by dropping two samples

fir decimation filters

saras - 2005-11-23 00:35:00
hi.. I wnat to design a fir decimation filter with 32 taps , input width 16, coefff width 16 .plz give me suggestions to implement this. ...fir decimation filters

Increase resolution through decimation

mariking - 2007-05-28 08:52:00
Hi I need to take a standard 8bit ADC which samples at 40Msps increase the resolution by about 4 or 5 bits. I know that oversampling spreads the quantization noise over a wider bandwidth thereby decreasing the SQNR. So i can increase the resolution through decimation? How do I increase the resolu...Increase resolution through decimation

Re: Polyphase decimation

One Usenet Poster - 2005-11-18 09:26:00
Praveen wrote: > Hi > > I am implementing a polyphase decimation of a 8k signal by a factor of > 20. I have designed a filter of pi/20, which means there are 20 > subbands. In case of decimation, the input gets shifted by a sample at > each time instant and then convolved with all the...Re: Polyphase decimation

CIC filter

Tom - 2008-04-30 15:26:00
I read in one of the literature about a CIC filter with decimation of 3.5. As far as I know CIC decimates by integer only. Is there a way to build a CIC with decimation of 3.5 ? Tom ...CIC filter

Interchanging FIR and Decimation operation
0 - 2005-04-09 14:50:00
Hi all, I have a yet another decimation question rather a decimation and a FIR filter question. I have 64K input samples that are filtered using a 3 tap - 2nd order FIR filter, say [a1 a2 a3]. After filtering they are decimated by 8. I want to reverse this operation such that I decimate fi...Interchanging FIR and Decimation operation

Re: FFT Radix

bharat pathak - 2008-02-02 04:43:00
I have not heard of mixed radix. but split radix is when you use both radix2 and radix4 to compute N point FFT. your output or input ordering/reordering will depend on if you are implementing decimation in time or decimation in freq algo. if you are doing decimation in time then you have to re...Re: FFT Radix

how to caculate the ripple of sigma-delta conveter

clarkkevin - 2006-03-03 04:22:00
Hello, Let's consider a Sigma-Delta analog to digital converter following by decimation filters. Do the passband ripples of the decimation filter play a significant role in not to degrade the precision afforded by the Sigma Delta ? I have been said that if a Sigma Delta converter to caculate the ripple of sigma-delta conveter

Re: Multistage interpolation question

Rick Lyons - 2008-01-27 17:19:00
Hi Guys, Wow. Thanks for all the replies. You've given me a lot to think about. One of the things that prompted my question is the fact that if we need to decimate by a large factor D, we can decimate in two stages (decimate by D1, followed by decimation by D2) to reduce the overa...Re: Multistage interpolation question

decimation filter delay

klusner - 2009-03-13 10:11:00
Hi members I am new to multirate dsp ,I understand that to down sample you need to have antialias filter bandlimited to Fs/2(Fs output sampling rate)and take the M (decimation factor)samples and discard M-1 samples. My questions are 1)Is antialias filter itself called decimation filter 2) delay...decimation filter delay

Decimate by 2 - DDC FI at 3fs/4

slayerz13 - 2011-03-17 09:19:00
Hello, I am studying a DDC working with FI = 3fs/4, and I have something that I don't understand for the quadrature demultiplexing. Here are the steps of the quadrature downconversion of the studied system : 0) The signal at FI is sampled at Fs. This is what I receive in my DDC 1) The centr...Decimate by 2 - DDC FI at 3fs/4

Fractional decimation

tharris00 - 2009-03-01 17:41:00
Hello, I've been studying polyphase decomposition, decimation, interpolation and fractional decimation. I think I have a handle on what I'm doing, but there's one thing I don't understand... Do you have to have greater than an L*Mth order filter in order to use polyphase decomposition to put t...Fractional decimation

Re: Fast down sample filtering

Grant Griffin - 2009-12-10 08:09:00
Eric Jacobsen wrote: > On 12/9/2009 7:54 AM, km wrote: > > Hi All, > > Does anyone have a suggestion for a fast down sampling filter? > > For N:1 reduction, add N consecutive samples together and output that. > Move to the next window of N samples. > > The response will not be...Re: Fast down sample filtering

Combining multiple CIC decimation filters in series

SRB - 2012-10-31 09:45:00
Hi All I'm designing a CIC filter to be used at high decimation rates (e.g. 4000) and am considering whether it could be beneficial to use more than CIC filter in series. For example, rather than having one CIC that decimates by 4000 I could use four CICs that decimate by 10, 10, 10 and 4x respecti...Combining multiple CIC decimation filters in series

decimation and resolution

alb - 2014-10-31 11:41:00
Hi everyone, I have an encoder which is delivering 22bit data for a 360 rotation. The rotation is accomplished in ~800ms but the serial link from the encoder is running such that we will sample values at 25KHz (that is a requirement). It roughly means we are grossly undersampling the amo...decimation and resolution

using IIR or FIR to implement the lowpass filter for downsampling?

Nasser M. Abbasi - 2012-03-05 05:34:00
For downsampling (decimation) one normally uses low pass filter before downsampling (anti-aliasing filter). I have thought that FIR is the best choice here for the low pass filter implementation for this case. But I was reading this page: IIR or FIR to implement the lowpass filter for downsampling?

How to implement an efficient ALL-PASS decimation?

liubenyuan - 2008-07-19 11:56:00
Hi all: I want to implement a Decimation with D=6 to decimate from 5Mhz to 833Khz, but all the 833Khz content is with interest, so the priori low-pass filter seem to have a very sharp transition width, which is hard to implement. so anyone got some ideas? ...How to implement an efficient ALL-PASS decimation?

decimation alias

sukram - 2008-07-23 12:49:00
I'm usig CIC5 decimation filter, which is part of a larger signal processor chip, decimation is M=8, the input frequency is Fs. Since CIC filters only have infinite attenuation at f=Fs/8*k , k={1..7}, a considerable amount of Alias will 'fold' into the output data stream's spectrum between 0...Fs/16...decimation alias

FIR Filter

vengadeshkumar - 2008-09-12 19:32:00
Hi, I have sampled the sinosoidal signal of 200Mhz at a rate of 500Mhz and i made decimation by factor of 25 on the above samples.The o/p of decimation is 20 mhz signal..I passed the above signal to a Digital bandpass filter( 198mhz--202Mhz).Later if i take the absolute value of the filter op ..w...FIR Filter

is there easy way to know which decimation phase got selected?

bharat pathak - 2010-09-30 09:45:00
Assume that i am doing decimation by 64, first by filtering and then throwing. This is implemented the same way in RTL and C. But there might be a data shift in input. Maybe one more or one less. This would essentially be same as selecting a different phase of the filter. Assuming that the there easy way to know which decimation phase got selected?

Question about Sigma-Delta conversion/decimation

Kiran - 2007-06-12 11:35:00
Hi all, My question is related to sigma-delta conversion. I understand the analog side of this, i.e. the modulator, and have developed a matlab simulation which gives me 1's and -1's output for any input signal. Essentially, this is the high data rate 1 bit output of the sigma delta modulato...Question about Sigma-Delta conversion/decimation

Interpolation and decimation

seb - 2004-01-13 22:10:00
Hello, i am looking for decimation and interpolation technique in order to, given a sampling rate fs, obtain a new sampling rate like (a/b)*fs. A way to to do is to decimate and then use linear interpolation... Is there some other ways (documents) to do this ? If so, have you got some boo...Interpolation and decimation

Order of cascade in IFIR filter

2014-10-06 10:34:00
I'm trying to reduce the circuit size of a multi-channel FIR filter used pr= ior to decimation. The multi-channel structure already makes use of the decimation factor to r= educe the overall circuit size - only 1/DecimationFactor outputs for each c= hannel are actually calculated.=20 I want...Order of cascade in IFIR filter

Root raised cosine decimation

vali_alex - 2007-10-02 08:54:00
Hi, I have a root raised cosine in a receiver whose input is a 16x oversampled signal. How do I do the decimation at the output, or how to find with sample out of 16 to keep? Is there any site or book where I can find information about this. Thanks ...Root raised cosine decimation

Re: Decimation filter: Output magnitude response

analog_fever - 2010-07-06 15:09:00
> > analog_fever wrote: > > > > > I have a decimation filter which decimates by 100. > > > > > Input sampling frequency fclk1 = 1.6MHz, > > > Output Sampling freq flck2 = 16kHz. > > > > > For the input, I use fft function in matlab, and get the magnitudes of > my > > > frequency resp...Re: Decimation filter: Output magnitude response

easy resampling bandwith question ...

sammy davis jr. - 2003-06-25 12:34:00
hi all, let's say i want to resample to 4/5 the input samplerate, i.e. interpolate 4X then decimate 5X. for both steps lowpass filters need to be designed. according to, it is sufficient to 1. determine cutoff freq. for the interp. filter 2. determine cutoff freq. for the dec...easy resampling bandwith question ...

Re: frequency respons of halfband filter?

alex65111 - 2009-04-17 00:58:00
All thanks for attempts to help me but I have not understood where I am mistaken. Let's try to ask a question easier and particularly. Let's assume at us there is a system consisting of the filter and following for it decimation. The impulse response of filter H=[0.033402 0 -0.015082 0 0...Re: frequency respons of halfband filter?
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