Digital Signal Processing 

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I am selling out some of the implementations of double complementary lattice wave filters that I use. Belive me when I say "when you get the hang of these type of filters you will never want to use anything else. " But as it is very difficult to find nice and easy and good Lattice Wave Ccode implementations I have put my implementations for sale.
THE VERY SPECIAL THING OF MINE IS MY METHOD OF MAKING THEM PHASELINEAR THUS P H A S E  L I N E A R I I R  F I L T E R S You are most likely a smart guy and can do this stuff yourself but think of the time you save. You get ccode filter coeficient generation, ccode filter implementation, ccode FFT code, ccode magnitude generation, and a ccode method for phase linearity. Now, if you want to know about FFT:s get the original papers written by Cooley and Tukey for the FFT algorithm from about 1965. I bought them in an IEEEsale a number of years ago just for the fun and it was well worth it. This is a gold mine as I have worked more than 8 years with these types of filters in many possible configurations and as I was told impossible configurations of these filters. I have done multirate filtering, filterbanks, decimation, interpolation, and lots of stuff. The implementation has never failed me. But I Still keep some secrets even though this C code implementation shows what other people get doctorate degrees in.
The output of a lattice wave double complementary filter is simultaneously:
This is the double complementary property and if you add together the two signals you have the complete magnitude again. Thus they are extremely good and efficient in filterbanks, multirate or not. The power in the signal is always kept intact even if it is splitted into different partitions and this I think is unique for filters. Lattice wave double complementary filter does not "explode" and are extremely stable. It is thus possible to change the filter coeficients in realtime. On the fly without that the filters behave strangely. This is very good if you have adaptive filtering processes. The Speed of an IIR filter and the stability of an FIR filter.
If you search in the internet for "lattice wave" you get a lot of additional information. They build on Gazsi, L., ''Explicit formulas for lattice wave digital
filters'', IEEE Trans. Circuits Syst., 1985, Vol. CAS32,
pp. 6888. You should really get this article, it is a beauty. However as I implemented the filters in floating point DSPs I simplified the filter implementation algorithms even further. The C code that you buy is not complicated, it is ANSIC, and should easily compile on any system. It contains C code that generates filter coefficients for
as you can see in the following code. You have samplingrate, cutofffrequency, and filterorder. Filter order is 1,3,5,7.. thus an odd number. lw_butterworth_coefficients(&butterworth[0], 20000.0, 5000.0, order) ; And in addition You get one of my methods implemented of making linearphase filtered data that some measurement systems require or even telephone systems. I have still a better one a linear phase filter without impulse response but that is my BIG SECRET that you can buy for more $$$ if you contact me. This linearphase filter method works faster than what FIR filters can accomplish given the same data. I presume continuous input data (for a number of milli seconds anyway). The code filters an Impulse response for the three types of filters and generates text files that can be read by Excel. The code also contains FFT and magnitude calculation so that you have text file outputs for the filter magnitude. I use the Brigham method in the C  code for FFT where you use a 512 points complex FFT for 1024 points of real values. It goes quicker. It takes some time to execute the C code but that is because of that it creates text files on your system and writes into them and then because of that excel likes a "," instead of a "." for like 0.00345 it converts all "." to "," and that also takes some time. Excel likes 0,00345 for decimal number. The ouput is thus
You can see the filter magnitude for

Here are the magnitudes of the 3 filters FFT:ed phase linear filter response giving 6 outputs. And here is a link to excel file. CLICK on following image for greater detail.


Here is a link to excel file for Butterworth impulse response. Both NONlinear and linear And below you have the LINEAR PHASE impulse response of both low and highpass filtered impulse that is later inserted into the FFT. CLICK on it for greater detail


Both impulse response of Butterworth Linear phase and NON linear phase. The first impulse is the linear phase filter and you can see how nice and symmetric it is. The nonlinear filter tilts, and you can see that at point 14 the pink point is higher then at point 16. This is due to the unstationary part of the difference equation that makes the filter. This is not seen for the linear phase filter as it is only running in the stationary part of the difference equation. That is what i believe anyway and you can see the difference and this difference is vital when building measurement systems. I learned me that the hard way as I built road measurement systems and were actually out on the road and measured the bumps decimeter for decimeter.
A real thing like a small stone with very spiky edges, in the asphalt, is seen in the filter as an impulse, and it has to look the same in the output data also. and not shifted by phasedistorsions in the filters.
You can click on the image to get up to 1600 pixels


The C code is not very huge and the filter code is even shorter I have had so many fights with managers without software experience, It is not that they are stupid,


Take your time to think about all the benefits you can have. And these filters are HOT!

Pay now $99 through PayPal. 1. Click the Buy Now button. Oberon Data och Elektronik AB will never be aware of your card details at any point. Payment is handled securely and safely by PayPal. Then you get a link via email where you can download the software. 

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