Learning Experience:NOISE CANCELLATION USING LMS ADAPTIVE FILTER

This was the last experiment of our DSP practicals and was group experiment. In this we were asked to find applications of DSP and patents related to that application. The application we selected was Signal noise reduction. My group member were Jaskirat Kaur, Pratik Keny And Vikita Jadhav.

We reffered to the following patents

1. Adaptive signal processor using Newton/LMS algorithm.

2. Method and Filter for enhancing a Noisy speech signal.

3. Noise Cancelling Microphone System.

4. LMS Adaptive filter.

5. Modified LMS Filter.

I referred and studied "Modified LMS Algorithms for Speech Processing with an Adaptive Noise Canceller" by Julie E. Greenberg,

Description:    Newton/LMS algorithm is used in adaptive signal processors to remove noise, but it has  a disadvantage that statistical characteristics of the input data should be previously known. So this patent eliminates this problem. It is based on Newton/LMS Algorithm. It is stated that instead of giving the input signal directly, the adaptive signal processor is designed to first compute Auto-correlation matrix of the input signal and then find inverse matrix of auto-correlation matrix by executing DFT and IDFT.  Thus it reduces the hardware requirement and the hardware can be realised easily.

Application:   Our application was to remove noise from a given speech signal using LMS adaptive filter. This was a software based application and code was written in SCILAB. We took a audio signal(noise free) and added noise to the signal using rand() function of scilab. Now this Noisy speech signal was given as input to the lms adaptive filter. At the output we recovered the original audio signal. The Noisy signal and the output noise-free signal could be heard. Through this application based experiment we learnt    1.how to search patents online.   2.To check plagiarism of documents.  3. functions of scilab(like how to add audio files, how to play audio, how to add noise/disturbance to audio, how to plot graph)




for paper and patent Follow this link
https://drive.google.com/open?id=0BxR8_fiX2NsmWl9MenZoZmxSejg