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-...

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:
...

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...

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?!
...

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...

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...

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...

Rick Lyons wrote:
> It took me a while to find the darned post of mine.
> My post was:
>
> From: R.Lyons@_BOGUS_ieee.org (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...

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...

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...

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...

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...

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...

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...

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
http://www.dsprelated.com/showmessage/...

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...

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 hol...

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...

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...

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...

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...

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...

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?
...

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...

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...

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 inp...

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 dspguru.com, it is sufficient to
1. determine cutoff freq. for the interp. filter
2. determine cutoff freq. for the dec...

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...

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
...

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
...

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...

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...

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...

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...

> > 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...

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...

Dear all,
I have a question linked to the decimation of a signal.
Let's have a signal x(n), and X(z) its Z-transform. If we decimate this
signal, i.e. xe(n) = x(2n), we obtain the following Z-transform :
Xe(z) = 1/2 [X(z^1/2) + X(-z^1/2)]
My question is : is there a way to obtain a signal ...

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:
http://www.dspguru.com/dsp/faqs/multirate/decimatio...