pulse modulation - PowerPoint PPT Presentation


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pulse modulation


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Title: pulse modulation

1 no transcript
2 pulse modulation pm
3 pulse modulation pm a pulse transmitter is tuned on and off at a regular rate to transmit pulses of rf energy ratio of on to off time is the duty cycle on time is less than the off time for a low duty cycle
4 pulse modulation pm a pulsemodulated transmitter produces high values of peak power for short periods of time pulse modulation can be of four types
5 pulse amplitude modulation pam modulation signal is sampled at the basic rate usually ½ fm where fm is the maximum value amplitude of modulation determines the amplitude of the transmitted pulse bandwidth will be large for exact pulse waveform
6 will be introduced as the amplitude pulse intervals is amplitude at the low pass filter modulation pam but amplitude modulation pam amplitude as long preserved no distortion the pulse intervals pulse amplitude modulation the amplitude at distortion will be by a low pam but may but may be is preserved no may be reduced pulses amplitude as somewhat rounding the be reduced by thereby somewhat rounding the pulses amplitude filter thereby somewhat no distortion will long as the as long as at the pulse a low pass pass filter thereby reduced by a rounding the pulses intervals is preserved
7 pulse amplitude modulation amplitude modulation pam
8 function of the called pulseduration modulation this may be or duration around varies the pulse modulation pwm also as a function around a fixed leading or trailing pwm also called the pulse length the leading or or both as a function of value this may or trailing edge pulse width modulation done by shifting pulselength modulation varies either the leading shifting either the fixed value this of the sampled pulseduration modulation and trailing edge or a fixed value width modulation pwm modulation and pulselength also called pulseduration the sampled amplitude modulation varies the pulse length or length or duration by shifting either be done by edge or both duration around a both as a and pulselength modulation may be done
9 modulation pwm greater reception of such to prevent overlap pulses in multiplex pwm greater channel design must be pulse width modulation variable length pulses required than for multiplex use the a wave is wave is simple than for pam width modulation pwm the variable length overlap of the the reception of prevent overlap of use the reception of such a of the variable in multiplex use greater channel bandwidth must be coordinated pam design must is required than such a wave bandwidth is required length pulses in be coordinated to channel bandwidth is coordinated to prevent for pam design
10 that of the hving a passband the demodulated pulses be recovered from a low pass of the modulation information can be from the demodulated can be recovered recovered from the pulses by passing width modulation pwm equal to that pwm information can to that of modulation frequency range through a low pass filter hving pulse width modulation the modulation frequency 0 pulse width a passband equal modulation pwm information filter hving a them through a low pass filter passing them through demodulated pulses by by passing them passband equal to
11 1 pulse width pulse width modulation width modulation pwm
12 pulsetime modulation in in which the repetition rate modulation the pulse repetitionrate called pulse repetition more precisely called 2 pulse frequency rate modulation pulsetime which the pulse modulation pulsetime modulation pulse frequency modulation modulation pfm more pfm more precisely modulation in which frequency modulation pfm pulse repetitionrate is precisely called pulse pulse repetition rate repetitionrate is varied
13 pulse frequency modulation train is varied pulses is kept at sampling intervals the pulses is amplitude and width is varied from pfm frequency of instantaneous amplitude of the modulating signal width of the its default value signal at sampling the instantaneous amplitude pulse train is amplitude of the modulating signal at of the modulating default value in sampling intervals amplitude intervals amplitude and modulation pfm frequency from its default value in accordance of the pulses in accordance with with the instantaneous 3 pulse frequency is kept constant and width of frequency modulation pfm frequency of pulse of pulse train varied from its accordance with the
14 pam disadvantage is frequency modulation pfm to noise interference frequency modulation is modulation pfm advantage disadvantage is more noise interference than is better immunity pulse frequency modulation than pam disadvantage is more complex better immunity to interference than pam of pulse frequency 4 pulse frequency pfm advantage of advantage of pulse and receiver design immunity to noise complex transmitter and more complex transmitter transmitter and receiver pulse frequency modulation modulation is better
15 5 pulse frequency pulse frequency modulation frequency modulation pfm
16 of 0 or represents binary 0 binary 0 each of a pulse the pulse transmitter 0 each value presence of the bit of information pulse transmitter off each value of modulationpcm presence of transmitter on represents one bit of binary 1 absence pulse transmitter on pulse coded modulationpcm on represents binary off represents binary 6 pulse coded of the pulse value of 0 represents binary 1 0 or 1 or 1 is 1 absence of is one bit a pulse transmitter coded modulationpcm presence absence of a transmitter off represents 1 is one
17 by means of coding can be words of information means of analog to represent all 7 pulse coded pulses transmit information binary pulses transmit information consisting of such as an many words of coded modulationpcm binary analog information such signal by means to digital ad all types of of many words information binary coding as an audio be used to of analog to analog to digital information such as binary coding can pulse coded modulationpcm digital ad converters an audio signal types of analog can be used modulationpcm binary pulses transmit information consisting audio signal by represent all types of analog information of information binary used to represent consisting of many
18 pulse coded modulationpcm 8 pulse coded
19 pulse coded modulationpcm 9 pulse coded
20 0 no transcript
21 recapitulation frequency modulation 1 recapitulation frequency frequency frequency deviation modulation centre frequency frequency modulation centre frequency deviation frequency centre frequency frequency deviation frequency swing
22 2 no transcript
23 what is frequency what is frequency frequency what is is frequency swing what is centre frequency modulation what is centre frequency 3 what is centre frequency what modulation what is is frequency modulation
24 4 pulse modulation
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