 Hello friends, myself Ilya Arsandhane, assistant professor from Department of Electronics, Valchin Institute of Technology, Sulapur. Today, we are going to see what are low frequency noises. So, these are the learning outcomes. At the end of this topic, students are able to explain the effect of noise and analyze different types of noises. Types of frequency noises such as low types of low frequency noises such as flicker noise, burst noise and avalanche noises. So, first we are going to see again what is meant by or how noise is defined. So, as we know noise may be defined as unwanted introduction of energy which tends to interfere with proper reception and reproduction of transmitted signal. So, noise hence it can limit the range of the systems. Noise may sometimes even force a reduction in the bandwidth of a system if it affects the sensitivity of the receiver also. Similarly, electrical noises are undesirable noises that fall within the passband of the signal. Passband basically when we are considering the filter then at these points the electrical noises may fall or get suppressed. Similarly, noise is can also be called as a random energy that interfere with the information signal. In radio receiver, in radio receiver noises may basically produce a hiss noise in the loudspeaker at the output as we have seen in our day to day life we can we can see this particular point that is a hiss is produced in a loudspeaker when there is a no input voice from the mic. So, that particular hiss noise is called as the it is the unwanted signal which is called as the noise. So, these are the sources of the noise. So, as you can see noise is basically further divided into two parts internal and external. Similarly, the external is further divided as atmospheric noise, extraterrestrial noise, industrial the internal noise basically define further categorized as thermal noise and short noise. So, as we have seen atmospheric noise basically they include cosmic noise and solar noises, industrial noise the turning on and off of the electrical machine drilling, stamping all these noises come under the industrial noise, extraterrestrial noise basically these are due to the these occur in the space due to the stars and the planets. Cosmic noise is one type of the noise which come under the extraterrestrial type of the noise. Similarly, internal noise, thermal noise this particular thermal noise as we have seen it occurs due to the it it basically occurs due to the different electronic as well as electrical components in a circuit such as resistors capacitors inductors transistors etcetera and short noise these are the noise which are occurring or which affect the low frequency type of the signals and these are majorly affecting the low frequency signals. So, low frequency signals or flicker noise, active devices or integrated circuit devices, diode transistors etcetera also exhibit a low frequency noise which is frequency dependent that is it is not uniform and hence this type of noise is called as a flicker noise. When we consider the spectrum density of the noise here the noise spectrum density increases as the frequency decreases hence it is given by 1 upon f into the noise. So, flicker noise is basically due to the impurities in the material which in turn cause charge carrier fluctuations. So, charge carrier fluctuation fluctuations is nothing but charge carrying components are electronic electrons and the holes. So, whenever there is a random movement between the electrons and the holes these movement basically called fluctuations and due to these fluctuations the flicker noise gets introduced. In semiconductors when we consider flicker noise arises due to the fluctuation in carrier densities such as whenever there is a current flow from in whenever we are considering a current flow in a transistor from emitter base to emitter collector at that particular point there is a flow of electrons as well as there is a flow of holes due to this due to this flow in semiconductors the flicker noise can get introduced. So, second type of noise is the burst noise this or popcorn it is also called as popcorn noise. So, burst noise is one kind of a low frequency noise. So, low frequency noise observed in BJT is called as burst noise. So, this noise basically occur in bi-junction bipolar junction transistor and hence it is called as burst noise noise in this noise appears as a series of burst at two or more levels when present in an audio system the noise produced popping sounds when this particular noise occurs in audio system then the noise produces a popping sound in the in the in the audio system. The spectral density for this when it is considered the spectral density increases as the frequency decreases it is same as that of as that of flicker noise. It is also a low frequency noise partition noise it occurs whenever there is a current this total current when it gets divided between two or more electrodes and this results in random fluctuations in the division or during the division. So, whenever we are considering a current which is flowing through a circuit and a and a point comes where the the current needs to be get divided in the circuit. So, during the division of the current at that particular point as soon as the current current gets divided there are some fluctuations produced there are some random fluctuations produced hence these fluctuations cause these these fluctuations cause noise to get introduced in the circuit such type of noise is called as the partition noise. The spectrum of partition noise is flat it is spectrum means spectrum noise spectrum density or the noise spectrum for the partition noise when it is considered it is very much flat. The diode diode is said to be less noisy than that of transistor for the same reason hence the third electrode me makes more noise. So, whenever we are considering a two terminal and a three terminal device when we compare these two electronic components then we find that the two terminal device which is nothing but a diode which has less partition noise whereas when we consider the three terminal electronic component which is a transistor it produces more partition noise because in that the current gets divided into three different terminals hence the partition noise is maximum. Avalanche noise so it it basically occurs due to due to avalanche that is ionizing where additional holes and electrons are produced which in turn contribute to the ionization process. So, whenever we are considering the density of electrons and holes then in P type in P type material and N type material if there are some specific some specific electrons and holes present then due to the then due to the energy flow or due to the due to the energy input signal input what exactly happens is there is the ionization takes place between the holes and the electrons and hence due to this noise gets introduced. So, the ionization process or the ionization phenomenon basically it produces a noise which is called as the avalanche noise here the noise spikes are present large noise spikes are present in the avalanche current sometimes these large noise spike currents are very much can cause a damage to the electrical circuit the spectrum density of avalanche noise is flat as that of the as that of the burst noise or it is also called as a popcorn noise when we consider zener diode then in zener diode avalanche noise is avoided is is majorly avoided. So, inter modulation noise so inter modulation noise or inter modulation distortion is the amplitude modulation of the signal containing two or more different frequencies in a system with non-linearities. So, basically the non-linearities occur in the frequencies itself modulating frequency is low and carrier frequency is high frequency the inter modulation between each frequency component will form additional signal at frequencies that are not just at harmonic frequencies of either, but also at the sum and different frequency of the original and are multiples of those sum and difference frequency. So, whenever we are considering the modulation process then there is a variation in the frequency with respect then there is a variations in carrier frequency as that of the modulating signal frequency due to the variations there are some additional frequencies produced which are basically called as harmonics and these are produced due to the sum and the difference that is variation variation is nothing, but in that we are considering sum and difference of the frequencies between carrier and the modulating frequencies. So, inter modulation is rarely desirable in radio and audio processing as it creates unwanted suppress emissions often in the form of sidements. So, the noise produced due to the inter modulation or variations in frequencies of carrier and modulating signal frequencies this is called as the inter modulation noise. Impulse noise is generally only minor and noise for analog data for example when noise voice transmission is corrupted by short clicks and crackles with loss of intelligibility. However, impulse noise is the primary source of error in digital data communication. So, whenever we consider a spike of energy then that would destroy any voice data of 50 bits or 4800 BPS. So, these are the references for you people for the further study. Thank you for watching the video.