FIR Filter coefficients using Excel Vba

We use different platforms to generate FIR and IIR coefficients. I tried to generate FIR filter coefficients using Excel. Low pass, High pass, Band pass, Band stop filters are implemented.

Why excel?
I choose excel for it's simple advantage, transparency. We can view each and every value and use them further easily. Understanding is better when we implement in Excel, and excel is also widely used as a professional tool in companies.

What is Excel vba?
Excel Vba is Excel with visual basic application within it. It helps to implement complicated formulas using visual basic and it's also very easy to learn. Its extension is .xlsm

Click below link to download Excel file.

Download excel file
Outlook of the Excel file

Download the .pdf file from below link showing how to use it.
How to use it.

FIR- finite impulse response
IIR - Infinite impulse response

To have better knowledge on digital signal processing, check out http://www.dsprelated.com/

Some interesting websites for Excel vba reference are,
http://www.excel-easy.com,
http://excelvbatutor.com/vba_tutorial.html
http://chandoo.org/wp/excel-vba/

I worked with IIR filter too. For any quiries comment.

Digital filter practical usage

Once filter design was mostly done by the analog filters. Even after the introduction of digital filters the design was not preferred due to the number of stages involved in the design. The need for memory to store the data(filter coefficients should be stored in digital filter design) made the design more costly.
So the design was only used where the cost was not a problem.

Later the digital filters made practical designs possible which are impractical and impossible by analog filters.

Example: Audio Frequency Range.

At this range the practical filter design was thought to be impossible, but with the advent of digital filter it is shown to be possible.

This gave reason for people to use digital filter. As the cost was still a concern the usage was still limited to only some design.

VLSI Development

As the VLSI developed, the cost of chips and power consumed, decreased drastically. This helped the development  of digital filter design and helped it to reach common people through the household instruments.

Advantages and Disadvantages of Digital Filter

Main advantages are as below
                 Programmability.
                 Reliability and Repeatability.
                 Component Drift.
                 Tuning Drift.
                 Precision Component.
          
           Programmability :
The main advantage of Digital filter lies with it's easy programmability  using software. Design process involves certain techniques through which filter coefficients are designed. With the designed Filter coefficients, the frequency response in magnitude and phase can be seen. Techniques to design these filter coefficients will be discussed further.
Corresponding Analog filter cannot be represented in software(see Practical usage).

        Reliability and Repeatability :
Digital filter is more reliable than analog filters by the same reason. In analog the component drift and tuning drift may be possible.Component precision can also influence the analog filter. These Problems are not there with the digital filter making it more reliable and repeatable than the analog filter.

Digital Filters make practical designs possible which are impractical and impossible

 by analog filters. 

Ex: Audio Frequency range

At this range the filter design was thought to be impossible as the tuning drift and also the component drift has a very sound effect. But with the digital filter, which don't have these problems, the design is shown to be possible. 

Main disadvantages of digital filter are

The number of stages involved in the digital filter design. 
High Power consumption in the filter because of the stages involved.
Cost involved with the hardware design.

Overview of Digital Filter Design and Design Stages:

Digital Filter is designed in discrete time signal to reduce or enhance certain aspects of signal.
(i.e. for example to remove some harmonics in a signal.)
This can be done with Analog filter too. But the reason why people prefer digital filter is its reliability over Analog signal. Analog Signal need not behave same with the variations in temperature, frequency and other conditions. But the digital filter don't have Such problems as the digital filter coefficients will be programmed or the values will be stored in it, this makes the filter output depend only on the values stored or programmed. So the reliability and repeatability of Digital filter makes it more advantageous than the Analog filter design.

Basic Digital design stages or the components used in Digital Filter are


             -->Analog to Digital Converter (To convert analog input to digital).
             -->Microprocessor (To Store the data).
             -->Digital to analog Converter (To Get the final Continues Signal Output).

Main Disadvantage of this filter is the cost involved with design, due to the number of stages involved and also due to the need of memory elements to store data. These are the main reasons why the digital filters were not preferred once.

Next Comes:
The briefing on "Advantages and Disadvantages of Digital filter."

Enjoy. Thank you. :D

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