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Pcs module 3 second part
Electronic and communication (ECE)
Visvesvaraya Technological University
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2 increases with the amplitude of modulating signal. modulating signal . t FM signal t 0 freq decrease PM signal 0 frequency increases Modulation Index and Sidebands: Any modulation process produces sidebands. when a constant frequency one wave medulate a carrier two sidebands are produces. A Idebands are usually the sum difference of carrier modulating frequencies. QUITE Scanned with OKEN Scanner o Scanned with OKEN Scanner 2 increases with the amplitude of modulating signal. modulating signal . t FM signal t 0 freq decrease PM signal 0 frequency increases Modulation Index and Sidebands: Any modulation process produces sidebands. when a constant frequency one wave medulate a carrier two sidebands are produces. A Idebands are usually the sum difference of carrier modulating frequencies. QUITE Scanned with OKEN Scanner o Scanned with OKEN Scanner Lower side bands carrier upper sidebands in. who . can w k, fc. f fusB tisB fc fm Modulation Index Ratio of the frequency deration to the modulating frequency is known as modulation. ender mp fd fm. 8 : In: what is the devration ratio of TV sound if the maximum deration is 25KHz max modulating frequency is 15KH2? mp Pd fm 2 25KHz 15KHz Q Scanned with OKEN Scanner o Scanned with OKEN Scanner Lower side bands carrier upper sidebands in. who . can w k, fc. f fusB tisB fc fm Modulation Index Ratio of the frequency deration to the modulating frequency is known as modulation. ender mp fd fm. 8 : In: what is the devration ratio of TV sound if the maximum deration is 25KHz max modulating frequency is 15KH2? mp Pd fm 2 25KHz 15KHz Q Scanned with OKEN Scanner o Scanned with OKEN Scanner Frequency Modulation Amplitude FM level Advantages of FM 1. Nouse immunity: unmunity circuits in the variations, which Main to noise, made possible receiver, benefit of FM over AM is its superior the clipper limiter sela remove all the noise effectively leaving a constant amplitude FM signal. 4. Capture effect In FM, interfering signals on the same frequence are effectively rejected Because of the amplited FM limiters demodulating methods used recevers, a phenomenon known as capture effect takes place when 21 more FM sign als occur simultaneously on same frequen . If one signal is more than turce the ampleted of other, the stronger signal captures weaker the channel, totally eliminating the signa 3. Transmitter efferency FM signals have a constant amplitude it is therefore not necessary to use linear amplifiers to increase their power level. Q Scanned with OKEN Scanner Scanned with OKEN Scanner Frequency Modulation Amplitude FM level Advantages of FM 1. Nouse immunity: unmunity circuits in the variations, which Main to noise, made possible receiver, benefit of FM over AM is its superior the clipper limiter sela remove all the noise effectively leaving a constant amplitude FM signal. 4. Capture effect In FM, interfering signals on the same frequence are effectively rejected Because of the amplited FM limiters demodulating methods used recevers, a phenomenon known as capture effect takes place when 21 more FM sign als occur simultaneously on same frequen . If one signal is more than turce the ampleted of other, the stronger signal captures weaker the channel, totally eliminating the signa 3. Transmitter efferency FM signals have a constant amplitude it is therefore not necessary to use linear amplifiers to increase their power level. Q Scanned with OKEN Scanner Scanned with OKEN Scanner 4 . It FM signals are always generated at a lower level then amplified a series of class C amplifiers to increase their power. Result is for greater use of available power because of high level of efficiency of class C ampers. Even more efficuent class D, E or F amplifiers are also used in FMFP I Disadvantages of FM. 1. Excessive spectrum Use BW of FM sugnal is urder than that of AM signal transmitting same information. Although, low to it is possible to keep modulation endex minimize reducing the modulation index also reduces nouse immunity to FM signal 2. Crewit Complexity ICs used in FM txcon are complex, they require lov little effort to used their price is as just as.. those of comparath AM circuits . Q Scanned with OKEN Scanner Scanned with OKEN Scanner 4 . It FM signals are always generated at a lower level then amplified a series of class C amplifiers to increase their power. Result is for greater use of available power because of high level of efficiency of class C ampers. Even more efficuent class D, E or F amplifiers are also used in FMFP I Disadvantages of FM. 1. Excessive spectrum Use BW of FM sugnal is urder than that of AM signal transmitting same information. Although, low to it is possible to keep modulation endex minimize reducing the modulation index also reduces nouse immunity to FM signal 2. Crewit Complexity ICs used in FM txcon are complex, they require lov little effort to used their price is as just as.. those of comparath AM circuits . Q Scanned with OKEN Scanner Scanned with OKEN Scanner 6 Frequency Demodulators Creants used to recover the original modulating signal from FM transmission are called frequency detectors des criminators. 1. slope Detectors slope detectors are the sumplest frequency arcuit a which use a tuned variations diode demodulators detector to convert frequency to voltage variations Recovered D1 modulating T) C2 signal G 11 L2 . . J slope Detector: The FM signal is applied to transformer resonant T1, made up of LIfL2. Together L2 f a form a series around , The signal vge induced into L2 apprears in The series with L2 Nge is taken across G. response curve is as Scanned with OKEN Scanner o Scanned with OKEN Scanner 6 Frequency Demodulators Creants used to recover the original modulating signal from FM transmission are called frequency detectors des criminators. 1. slope Detectors slope detectors are the sumplest frequency arcuit a which use a tuned variations diode demodulators detector to convert frequency to voltage variations Recovered D1 modulating T) C2 signal G 11 L2 . . J slope Detector: The FM signal is applied to transformer resonant T1, made up of LIfL2. Together L2 f a form a series around , The signal vge induced into L2 apprears in The series with L2 Nge is taken across G. response curve is as Scanned with OKEN Scanner o Scanned with OKEN Scanner K Fr. . Higher fee. produces It higherver . vge arross lowerful G. vege O. frequency As the carrier frequency varies above below its center frequency the tuned crisunt responds accordingly u If frequency is increased. across C1 goes hig her nice versa. ac vge across 9 is proportional to the freque ency of FM seonal. Voe go across Gas rectified into d pulses that appear across load R1, which are filtered into a varying dc signal which is original modulating signal. Duadvantage of slope Detectors , 1. Tuning of the urcuit : The main difficulty with slope detectors hes in tuning them so that the FM sunnal is correctly untered on the leaders edge of the circuit. QUICE Scanned with OKEN Scanner o Scanned with OKEN Scanner K Fr. . Higher fee. produces It higherver . vge arross lowerful G. vege O. frequency As the carrier frequency varies above below its center frequency the tuned crisunt responds accordingly u If frequency is increased. across C1 goes hig her nice versa. ac vge across 9 is proportional to the freque ency of FM seonal. Voe go across Gas rectified into d pulses that appear across load R1, which are filtered into a varying dc signal which is original modulating signal. Duadvantage of slope Detectors , 1. Tuning of the urcuit : The main difficulty with slope detectors hes in tuning them so that the FM sunnal is correctly untered on the leaders edge of the circuit. QUICE Scanned with OKEN Scanner o Scanned with OKEN Scanner The phase detector compares the 2 sign als generate an signal which when filtered will control the VCO. If there as a phase I frequency difference detector the FM VCO signals then the phase olp varies an proportion to the difference A The fultered adjusts the VCO frequency dn C to correct for the original frequency phase difference. This dc control ver as called error signal, which is also the feedback in the crimut. when no signal is applied, phase detector LPF are zero. VCO then operates at what is called free running frequency, its normal opera ting frequency as determined internal frequency determining components when an signal els applied, then phase detector compares VCO frequency to frequency produces an Vie proportional to frequency difference. The phase detector us a series of pulses that vary in width in accordance with the amount of phase shift frequency difference that exists 2 Scanned with OKEN Scanner Scanned with OKEN Scanner The phase detector compares the 2 sign als generate an signal which when filtered will control the VCO. If there as a phase I frequency difference detector the FM VCO signals then the phase olp varies an proportion to the difference A The fultered adjusts the VCO frequency dn C to correct for the original frequency phase difference. This dc control ver as called error signal, which is also the feedback in the crimut. when no signal is applied, phase detector LPF are zero. VCO then operates at what is called free running frequency, its normal opera ting frequency as determined internal frequency determining components when an signal els applied, then phase detector compares VCO frequency to frequency produces an Vie proportional to frequency difference. The phase detector us a series of pulses that vary in width in accordance with the amount of phase shift frequency difference that exists 2 Scanned with OKEN Scanner Scanned with OKEN Scanner B The alp pulses are then filtered into a devoe that is applied to VCO, such that it forces VCO frequency to move in a direction that reduces dc error voltage. VCO the detection which reduces amount of phase, The error voltage forces a frequency to change in frequency difference VCO Then, error voltage causes NCO frequency equal is to frequency Cat some point This condition said to be un a locked condition. NOTE Although the frequencies are 90 , equal, there as a phase difference them of which produces dc vge causing VCO to produce freq. that keeps creaut locked. If freq. changes, phase detector LPF produce VCO a new value dc control voltage that forces new freq. to change of until us it is equal to frequency. Any variation in frequency us matched locked. VCO freq. change, so that circuit remains VCO in PLL is capable of tracking the frequency over a wrde range. QUICE Scanned with OKEN Scanner o Scanned with OKEN Scanner B The alp pulses are then filtered into a devoe that is applied to VCO, such that it forces VCO frequency to move in a direction that reduces dc error voltage. VCO the detection which reduces amount of phase, The error voltage forces a frequency to change in frequency difference VCO Then, error voltage causes NCO frequency equal is to frequency Cat some point This condition said to be un a locked condition. NOTE Although the frequencies are 90 , equal, there as a phase difference them of which produces dc vge causing VCO to produce freq. that keeps creaut locked. If freq. changes, phase detector LPF produce VCO a new value dc control voltage that forces new freq. to change of until us it is equal to frequency. Any variation in frequency us matched locked. VCO freq. change, so that circuit remains VCO in PLL is capable of tracking the frequency over a wrde range. QUICE Scanned with OKEN Scanner o Scanned with OKEN Scanner 9 A PLLS are often used in signal conditioning applications , where at is desirable to pass signals only in certain range to reject signals outside of that range. PLL is highly effectively in eliminating the none interference on a signal. varations The ability makes of it useful in FM PLL to respond to applications. frequency lock range capture range fo for vco frequency frg: capture Lock ranges of PLL . produces exactly same FM signal as VCO can operate as a frequency modulator which of DI to This happens only when VCO is identical follous FM signal because error voltage VCO to the original modulating signal. VCO produced phase detector LPF forces track it Thus VLO must be identical Q Scanned with OKEN Scanner Scanned with OKEN Scanner 9 A PLLS are often used in signal conditioning applications , where at is desirable to pass signals only in certain range to reject signals outside of that range. PLL is highly effectively in eliminating the none interference on a signal. varations The ability makes of it useful in FM PLL to respond to applications. frequency lock range capture range fo for vco frequency frg: capture Lock ranges of PLL . produces exactly same FM signal as VCO can operate as a frequency modulator which of DI to This happens only when VCO is identical follous FM signal because error voltage VCO to the original modulating signal. VCO produced phase detector LPF forces track it Thus VLO must be identical Q Scanned with OKEN Scanner Scanned with OKEN Scanner Receivers Antenna V RF IF amplifier Moer Demedulator C amplt selective filter AGC Local oscellator speaker audio requency synthesizer amper for B of Rx , 2 sensitive selective receiver can be made using only amplifiers, selective filters a demodulator , This is called a tuned radio frequency TRF receiver One type of receiver which provides this kind of performance is called superheterodyne receiver to lower frequency, known as intermediate Superheterodyne receivers convert all synals frequency (iF), at which a single set of ampers filters as used to provide a fixed level of sensitively selectivity The key urcuit is the mixer, which acts f a simple amplitude modulator to produce sur as difference frequences. Scanned with OKEN Scanner O Scanned with Receivers Antenna V RF IF amplifier Moer Demedulator C amplt selective filter AGC Local oscellator speaker audio requency synthesizer amper for B of Rx , 2 sensitive selective receiver can be made using only amplifiers, selective filters a demodulator , This is called a tuned radio frequency TRF receiver One type of receiver which provides this kind of performance is called superheterodyne receiver to lower frequency, known as intermediate Superheterodyne receivers convert all synals frequency (iF), at which a single set of ampers filters as used to provide a fixed level of sensitively selectivity The key urcuit is the mixer, which acts f a simple amplitude modulator to produce sur as difference frequences. Scanned with OKEN Scanner O Scanned with 2. Mixers Local Oscullation RF is applied to local of the oscillator mixer Mixur of also receives an from a 1 frequency synthesizer. Mixe is signal, local oscellator signal the to nixer are A tuned curcuit at the of mixer selects the sum f difference frequences of these signals. difference frequency intermediate frequency (IF). Mixes may be a diode balanced transistor MOSFETS hot carrier duodes are preferred as mixers because of their low. nouse characteristic Local oscullator is tuned such that the frequence N can be adjusted over relatively urde range. local oscillator frequency is changed, mixer IF. translates As wide tange of frequencies to fixed 3. IF Amplifiers: modulation that appeared on the olo if of mixer is an IF signal containing RF same signal. This signal is amplified one more IF obtained ampl stages in these most stages of the recever gain Scanned with OKEN Scanner Scanned with OKEN Scanner 2. Mixers Local Oscullation RF is applied to local of the oscillator mixer Mixur of also receives an from a 1 frequency synthesizer. Mixe is signal, local oscellator signal the to nixer are A tuned curcuit at the of mixer selects the sum f difference frequences of these signals. difference frequency intermediate frequency (IF). Mixes may be a diode balanced transistor MOSFETS hot carrier duodes are preferred as mixers because of their low. nouse characteristic Local oscullator is tuned such that the frequence N can be adjusted over relatively urde range. local oscillator frequency is changed, mixer IF. translates As wide tange of frequencies to fixed 3. IF Amplifiers: modulation that appeared on the olo if of mixer is an IF signal containing RF same signal. This signal is amplified one more IF obtained ampl stages in these most stages of the recever gain Scanned with OKEN Scanner Scanned with OKEN Scanner 11 selective tuned circuits provide fixed selectivity since, the intermediate frequency is usually much lower than the signal frequency IF amplifiers are easier to design good Crystal ceramic SAW filters are used in most selectivity is caser to obtain IF sections to obtain good selectivity Some form receivers use DSP filter for selectivity. 4. Dinodularion Highly amplified IF signal is finally applied the to demodulator which recovers original modulating inform ation be a diode detector a quadrature Demodulator detector may a product modulator In digital superheterodyne radios, IF signal is digitized ADC then sent to a DSP where demodulation is carried out an algouthm. Recovered signal is then converted back to in analog form DAC. of demodulator is fed to an audio amplifier with sufficient Voe for non voice signals, detector may be sent power joan to operate a spealer. to TV, tablet, cell phone computer ,etc. Scanned with OKEN Scanner o Scanned with OKEN Scanner 11 selective tuned circuits provide fixed selectivity since, the intermediate frequency is usually much lower than the signal frequency IF amplifiers are easier to design good Crystal ceramic SAW filters are used in most selectivity is caser to obtain IF sections to obtain good selectivity Some form receivers use DSP filter for selectivity. 4. Dinodularion Highly amplified IF signal is finally applied the to demodulator which recovers original modulating inform ation be a diode detector a quadrature Demodulator detector may a product modulator In digital superheterodyne radios, IF signal is digitized ADC then sent to a DSP where demodulation is carried out an algouthm. Recovered signal is then converted back to in analog form DAC. of demodulator is fed to an audio amplifier with sufficient Voe for non voice signals, detector may be sent power joan to operate a spealer. to TV, tablet, cell phone computer ,etc. Scanned with OKEN Scanner o Scanned with OKEN Scanner 15 frequency Conversion : Frequency conversion is the process of translating a modulated signal to higher or lower frequency while retaining all the originally transmitted information are converted to a lower, selectivity intermediate can In radio receivers, raduo signals regularly where improved gain conversion. frequency , obtained. This is called down be satelute comm original signal is generated to a In frequency f then converted This is at higher a lower frequency for transmission. called Mixing conversion is a form of out amplitude a minur mod Principles analog Frequency multiplication carried converter. Function performed misor is called heterodyning. QUESTION Scanned with OKEN Scanner o Scanned with OKEN Scanner 15 frequency Conversion : Frequency conversion is the process of translating a modulated signal to higher or lower frequency while retaining all the originally transmitted information are converted to a lower, selectivity intermediate can In radio receivers, raduo signals regularly where improved gain conversion. frequency , obtained. This is called down be satelute comm original signal is generated to a In frequency f then converted This is at higher a lower frequency for transmission. called Mixing conversion is a form of out amplitude a minur mod Principles analog Frequency multiplication carried converter. Function performed misor is called heterodyning. QUESTION Scanned with OKEN Scanner o Scanned with OKEN Scanner Mixer forts for Is Juned fot fs Mixer to f3d circuit IF A or or sesonal fo filter to Is 2 Local osullator 2 1pps. to A The Mixer signal accepts fs, which is to be to translated to one A another sine wave frequency, from local , is osculator applied to is applied to other can It The a signal sine wave to be or any modulated reconscreeted translated seral be containing sidebands is the earrier r signal contains to be Oscillator modulating sional oscullator translated carrier, sidebands is when local signal are of mixer is Lo, fs, fopts, fo fs. or Q Scanned with OKEN Scanner Scanned with OKEN Scanner Mixer forts for Is Juned fot fs Mixer to f3d circuit IF A or or sesonal fo filter to Is 2 Local osullator 2 1pps. to A The Mixer signal accepts fs, which is to be to translated to one A another sine wave frequency, from local , is osculator applied to is applied to other can It The a signal sine wave to be or any modulated reconscreeted translated seral be containing sidebands is the earrier r signal contains to be Oscillator modulating sional oscullator translated carrier, sidebands is when local signal are of mixer is Lo, fs, fopts, fo fs. or Q Scanned with OKEN Scanner Scanned with OKEN Scanner
Pcs module 3 second part
Course: Electronic and communication (ECE)
University: Visvesvaraya Technological University
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