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IIR filters

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 IIR – Feedback is infinity Fir Filter are always stable, So we don’t have any poles & zeros Biquad Filter is second order recursive filter with infinity feedback which has two poles & two zeros.   When Coefficients are normalized then a0 = 1   Why we use cascading in Biquad filters ? Basically High-order infinite impulse response filters are highly sensitive to quantization of their coefficients and easily become unstable. But with first & second filters it is very less. So to make it stable, implement high order filters as serially cascaded Biquad sections which will make it stable by keeping all the poles inside the unit circle. Direct Form 1: From fig :   𝑧 − 1 Means delay by 1 sample 𝑧 − 2 Means delay by 2 samples Y[n] = 1/a0 (b0x[n] + b1x[n-1] + b2x[n-2] – a1y[n-1] -a2y[n-2]) Y[n] = b0x[n] + b1x[n-1]+b2x[n-2...
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Binary representation of numbers

 Binary representation of numbers In this we will learn how to represent a number in Binary format, Octa, Hex formats 1 - 0001               6 - 0110               11 - 1011 (B) 2 - 0010               7 - 0111               12 - 1100 (C) 3 - 0011               8 - 1000               13 - 1101 (D) 4 - 0100               9 - 1001               14 - 1110 (E) 5 - 0101              10 - 1010 (A)     15 - 1111 (F) Ex 1: Represent 56 in binary format        56 - (2^5) * 1 + (2^4) * 1 + (2^3) * 1 +  (2^2) * 0 + (2^1) * 0 + (2^0) * 0                  - (...
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Interface Protocols

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Protocols – Uses for communication with devices Communication are different types  Intra – Communication between two devices within device                             Ex: I2C, SPI Inter – Communication between two devices                              Ex: CPU & Microcontroller, UART Simplex Duplex - One way communication ex: Fm Half Duplex - Two-way communication but only receive or transfer at a time ex: walkie talkie Full Duplex - Two-way communication at a time ex: Mobile Synchronous - Will use clock signal to send or receive any data Asynchronous - Need to maintain same frequency while transferring and receiving using clock signal UART – U niversal A synchronous R eceive and T ransmitter We will transfer data using serial communication  It will use two wires Rx & Tx It is synchronous co...
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Acoustic Echo Cancellation

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  AEC - Acoustic Echo Cancellation Basically, from childhood onward echo means resound we listen when produce sound in empty room. We will call it as Room Echo which will be different from AEC. Echo will be very annoying problems to users of communication while using telephones, cellphones, microphones, speakers It can be formed when one-end voice echoed again to the same speaker from the other end microphone  It can be formed due to several other reasons also like positioning cell phone too away, not proper position of microphones, bad interior     AEC algorithm minimizes the effects by Cancellation, Suppression, Masking techniques It involves below different blocks  1. Normalized Least Mean Square (NLMS) is an adaptive filtering used to perform echo cancellation  2. Non-Linear Processing (NLP) used to remove the residual echos which are not removed with NLMS 3. Comfort Noise Generation used to generate some sort of noise to make sure the other en...
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DSP Basics

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What is DSP ? D igital S ignal P rocessor device which takes digital signal and alters them through different algorithms and provides the results within milliseconds. These are normally found in Speakers,   Mobiles.. In audio applications, DSP plays a key role to use different features like ANC, adaptive filtering, Noise suppression.. Digital Signal Processing : X(t) -> Anti aliasing -> Sample & hold ->  ADC -> DSP -> DAC -> Reconstructed signal -> Y(t) Audio Processing - Modification audio within same domain  Sampling - Converting the continuous signal into discrete signal  Importance of Sampling in DSP: Digital Representation: Enables analog signals to be represented digitally, which is essential for digital storage, processing, and transmission. Discrete Processing: Allows the use of digital algorithms and systems that are more robust and flexible compared to their analog counterparts. Accuracy and Efficiency: Facilitates precise...
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