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?!
...
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...
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 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...
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,
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...
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 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...
Hi, I am new to DSP and learning about sampling and related topics. I have
read a book and visited online sites but still am having problems
understanding :
1. Why do we need a filter (FIR) BEFORE we downmsample when we perform
decimation. I understand why for upsampling we need the filtering ...
Hi,
I've seen several cases where the chroma decimation, e.g.,
when going from YCrCb 4:4:4 to 4:2:2, is done by simply
throwing away every other sample. I have two questions
regarding this operation:
1. If there were a 1-D signal, simply throwing away
every other sample without first f...
Hi All,
I thank all of you, for your support, which I got previously. I am
hardware design engineer and working on sigma delta ADC. And my role
is to design decimation filter, basically I have to design a blocks
which converts single bit to multi bits output. I surveyed lots of
literature.
...
Hello All,
The task is to design the multiple cascaded FIR filters to do the
decimation. There are tough requirements about the resultant ripples in
the passband; the stage-by-stage design seems to be very inefficient.
Can you suggest a filter design software which can optimize the overall...
DSP gurus:
Concerning decimation by a rational scale factor, L/M, where
L = upsampling factor,
M = downsampling factor,
M > L (hence, decimation occurs)
Define Decimator A as
Input -> FIR bandlimit(L pi / M) -> Two-point interpolation -> Output
Define Decimator B as
Input ->...
Hi,
I have a problem, I have a oversampled (OSR =16) Digital Signal, prior
to downsampling a filter is used, a 16 Tap BandpassFIR filter wich
also have a Window.
1. Is there a document or approch how to calculate mathematically the
resolution / Accuracy after the Filter, the Window and af...
Hi All,
I have recently completed my DSP course (subject) which is part of my
engineering degree and I am very interested in DSP applications to Audio in
particular. I have decided to undertake a project which involves FFT
(probably I will use a Radix-2 to keep it simple for me) in hardware...
Hi,
i would like to know which is the best method for implementing a integer
sample rate converter (decimation /interpolation) in terms of quality.
the conversion rates required are (2,4,8,16) both decimation and
interpolation.i had tried with polyphase implementation and lagrange
interpolatio...
Jimm Avante wrote:
> I am new to FFT but after reading, all FFT starts butterfly operation during
> the
> middle of the frame. For example, a radix-2, it starts until N/2 sample has
> been
> read in from ADC, i.e. but(0, N/2-1), but(1, N/2), ...
>
> Is it possible to design it in su...
Hello,
I am using Linear feedback shift register(LFSR) to test Digital
filter(DF) because LFSR generate white noise and has a flat like spectrum.
Can anynody suggest when I pass white noise in DF, on what citeria should I
judge the filter (Device Under Test) is pass or fail ?? my fi...
Hi, everyone!
I read "decimation by integer" and "interpolation by integer factors"
in a DSP book.
I'm just wondering why integer factor to downsampling...
Sometimes, to resample signal by rational factor, people use conversion
oversampling(integer factor) -> low-passfilter -> dow...
I am trying to simulate a rational sample rate conversion architetcure
using CIC filters (decimation) and farrow structure (interpolation). Input
data is QPSK modulated and upsampled by a large factor (325 to be exact). I
try to decimate the signal by 125 in three stages. each stage is in turn a
C...
Could someone please refer to good, non-matematician-accessible discussion
of decimation-in-time vs decimation-in-freq FFT's?
Second, more confused, question.
The implementations I find online are d.in-time, but I'd like a
d.in-freq implementation if available (i think).
The idea is to build ...
"glen herrmannsfeldt" wrote in
message news:R_qdneUT0d873YfYnZ2dnUVZ_s6dnZ2d@comcast.com...
> Tim Wescott wrote:
>
>
> > Your biggest stumble is that you aren't synchronizing to
> > the bit rate. You should sample at the point where your
> > filters' outputs peak for any given b...
Hi everybody,
I am designing a decimation filter for a 16bit delta-sigma A/D. The
decimator will be a CIC decimate by 16 filter, followed by two FIR
filters to get the required attenuation. I have two questions as most
of my experience is in analog & not digital design.
1- The filter ord...
Thanks for the guys who aswered my decimation question, howver I am really
looking for irrational decimation, so I am clearing up the confusion:
I am trying to decimate bandlimited data by an irrational factor like
Tin/Tout = 2*sqrt(2) where Tout and Tin are the output and input sampling
tim...