## Interpolation using polyphase FIR filter: Finding coeffisients

Started by in comp.dsp12 years ago 18 replies

Hi, I have a datastream that is sampled 4800 times pr second, but the rf front end I am going to use accepts only input at 250000 samples pr...

Hi, I have a datastream that is sampled 4800 times pr second, but the rf front end I am going to use accepts only input at 250000 samples pr second. Clearly I need a 52,0833 times interpolation. To achieve this I have planned to first interpolate 625 times, and then decimate 12 times. I will do this in steps, for instance in steps of 5 for the interpolation, and 4 for the decimation. I...

## Interpolation with FIR filters

Started by in comp.dsp13 years ago 4 replies

Hi Can anyone please explain me about Interpolation using FIR filters? I dont understand how they can be used for...

Hi Can anyone please explain me about Interpolation using FIR filters? I dont understand how they can be used for interpolation. Thanks Anshu

## Spline Interpolation and cubic interpolation

Started by in comp.dsp13 years ago 3 replies

Hi How many data points does Spline and Cubic interpolation take to calculate a point?

Hi How many data points does Spline and Cubic interpolation take to calculate a point?

## Polyphase interpolation on an image with real value only

Started by in comp.dsp15 years ago 2 replies

Hi all, I encounter some "problem" while using polyphase filter for interpolation. I have implemented a 8 zero crossing with upsampling of...

Hi all, I encounter some "problem" while using polyphase filter for interpolation. I have implemented a 8 zero crossing with upsampling of L=32. The image I used are a simulated image with 4 sinc impulse response near the four corner. All pixels values are positive. While performing interpolation, such as for rotation operation, I found that some of the values return is negative? ...

## Interpolation

Started by in comp.dsp13 years ago 1 reply

Hi Does anyone know : Which interpolation method (in matlab or otherwise )is better for a non uniform data grid with complex numbers and...

Hi Does anyone know : Which interpolation method (in matlab or otherwise )is better for a non uniform data grid with complex numbers and Why? Thanks Anshu

## Interpolation techniques

Started by in comp.dsp13 years ago 2 replies

Hi Does anyone know: Which interpolation method is better for a non uniform data grid with complex numbers and Why? Thanks Anshu

Hi Does anyone know: Which interpolation method is better for a non uniform data grid with complex numbers and Why? Thanks Anshu

## spline interpolation

Started by in comp.dsp13 years ago

hi friends, i have an interpolation function with 3 arguments. say h(x)=interp(x,y,z). i have to find out the value of h(x). so plz if...

hi friends, i have an interpolation function with 3 arguments. say h(x)=interp(x,y,z). i have to find out the value of h(x). so plz if any one knows it. mail it to me. thanks in advance rajasekar

## one pixel shift in 2D sinc interpolated image

Started by in comp.dsp16 years ago 6 replies

I have used sinc interpolation (by zero padding 2D FFT) to oversample an image along one axis. The results look good, but if I make the new...

I have used sinc interpolation (by zero padding 2D FFT) to oversample an image along one axis. The results look good, but if I make the new and old images the same size and overlay them, the interpolated image seems to be shifted by about a pixel (maybe less) along the direction of interpolation. The scheme I used was pretty simple (described here for interpolation of rows): 1) ...

## Osculating/Hermite Interpolation on sampled data

Started by in comp.dsp14 years ago 10 replies

I was thinking about osculating polynomial interpolation (of which Hermite is the first order member) in relation to sample rate conversion. As...

I was thinking about osculating polynomial interpolation (of which Hermite is the first order member) in relation to sample rate conversion. As I understand it, osculating interpolation is a method where the interpolating function is a polynomial that matches a function's value(s) plus a certain number of its derivatives (0, 1, 2*, etc.) at those values. This makes good sense when you are a...

## 1D cubic B-spline interpolation

Started by in comp.dsp13 years ago

Hi, Following this...

Hi, Following this discussion http://groups-beta.google.com/group/comp.dsp/browse_frm/thread/ffc12437efe8= 4f92/73394dc71a49b15b?lnk=3Dst&q=3D&rnum=3D1&hl=3Den#73394dc71a49b15b about which kind of interpolation suits my needs, I chose to try and implement one-dimensional cubic B-spline interpolation. However I failed, the result is a long way off what's supposed to happen, and I'm afrai...

## Pulse shaping + interpolation

Started by in comp.dsp13 years ago 2 replies

Hello, I'm supposed to design a transmit chain with a root-raised cosine pulse shaping filter followed by some interpolation stages. The...

Hello, I'm supposed to design a transmit chain with a root-raised cosine pulse shaping filter followed by some interpolation stages. The RRC-filter shall interpolate by 2, and its output shall be interpolated by 8, resulting in a total interpolation of 16. I'm told that the total characteristics of the RRC-filter + interpolation chain shall resemble a root-raised cosine response. I'm ...

## FFT interpolation Matlab

Started by in comp.dsp2 months ago 4 replies

Hi, I am trying to use interpolation to detect an FFT peak between bins however my interpolation results in the same peak as the FFT. I am...

Hi, I am trying to use interpolation to detect an FFT peak between bins however my interpolation results in the same peak as the FFT. I am inputting a 50Hz sine wave.. Sampling freq is 6500hz and I have 2048 sample points. There fore my bin freq is 3.17hz which multipled out gives me a 50.8hz nearest bin frequency which is what my code is giving me. I am trying to see where my i

## zero-pad as an interpolation in frequency domain?

Started by in comp.dsp11 years ago 33 replies

Hi all, I read somewhere that we can derive mathematically the zero padding equation to show that zero-padding is simply an interpolation...

Hi all, I read somewhere that we can derive mathematically the zero padding equation to show that zero-padding is simply an interpolation in frequency domain. I tried to derive but still could not see the interpolation operator. Can you please tell me how to derive it from DFT formula? Thanks

## Interpolation

Started by in comp.dsp12 years ago 6 replies

Hi Friends, I hav a signal(time_domain). 80ms/s. Sample distance = 12.5ns. I wana interpolate by factor 6. Wht should i use, interpolation...

Hi Friends, I hav a signal(time_domain). 80ms/s. Sample distance = 12.5ns. I wana interpolate by factor 6. Wht should i use, interpolation filter? Amrish.

## RBF interpolation

Started by in comp.dsp13 years ago 1 reply

Hello, I want to implement RBF interpolation in Matlab for 2D signal (image) interpolation. What I like to know is: 1- Is there...

Hello, I want to implement RBF interpolation in Matlab for 2D signal (image) interpolation. What I like to know is: 1- Is there any freely available RBF interpolator source code for Matlab? 2- How can I implement it? I read a lot about its theory but I couldn't figure out how an implementation is working. 3- If there is a C implementation, I maybe able to port it to Matlab ...

## interpolation and filtering

Started by in comp.dsp13 years ago 12 replies

Hello, I know that one way of interpolation is low pass filtering. But I think any other type of interpolation (such as spile or linre...

Hello, I know that one way of interpolation is low pass filtering. But I think any other type of interpolation (such as spile or linre ,...) can be modeled as a low pass filter with different frequency response. Am I wrong? if no, where can I read more? for example what is the frequency response of a spilne interpolator? Regards

## sample rate conversion: Windowed-Sinc v.s. Lagrange v.s. B-Spline?

Started by in comp.dsp14 years ago 12 replies

Hi all, I'm working on a DSP project, which needs an arbitrary sampling rate converter. I searched several interpolation algorithms -...

Hi all, I'm working on a DSP project, which needs an arbitrary sampling rate converter. I searched several interpolation algorithms - windowed-sinc, Lagrange, and B-Spline. However, I can't determine which algorithm is suitable for low-ordered interpolation filter. According to my understanding, the performance of windowed-sinc interpolation(with table look-up) can be easily estimated by the sp...

## Interpolation

Started by in comp.dsp13 years ago 2 replies

Hi Is there any kind of interpolation like spline, nearest neighbor(weighted) that can be used for interpolating a nonuniform...

Hi Is there any kind of interpolation like spline, nearest neighbor(weighted) that can be used for interpolating a nonuniform data ? Suppose x = [1 2 4 5 6 8 9 10 12....] and y=f(x) = [0 -2 4 -3 5 -6....] and i want to find yy corresponding to xx = [1.8 5.8 9.8..] How should I proceed? And can somebody please tell me equations used in spline as applied to this example!! Thanks ...

## Trying to understand CIC interpolation

Started by in comp.dsp12 years ago 9 replies

I am using Matlab's mfilt.cicinterp on a piece of data. Out of curiousity, I also tried to write my own CIC interpolation filter. I referred...

I am using Matlab's mfilt.cicinterp on a piece of data. Out of curiousity, I also tried to write my own CIC interpolation filter. I referred to Hogenhauers original paper (An Economical Class of Digital Filters for Decimation and Interpolation) as well as Matlab's documentation for mfilt.cicinterp at http://www.mathworks.com/access/helpdesk/help/toolbox/filterdesign/index.html?/access/helpdesk/h el

## Re: Sampling, Again -- Updates

Started by in comp.dsp8 years ago 4 replies

If I can jump in here, I have to say I don't follow why you call a zero order hold an interpolation. I can see why it is *used* in the context of...

If I can jump in here, I have to say I don't follow why you call a zero order hold an interpolation. I can see why it is *used* in the context of interpolation, because of its simplicity. But if it is being done in real time where the subsequent data is not available for computation (because it does not exist yet), it is not really interpolation, by definition. When I looked u