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PAM vs PWM vs PPM-Difference between PAM,PWM,PPM

This page on PAM vs PWM vs PPM describes difference between PAM, PWM and PPM. All these are pulse analog modulation techniques.

PAM

In PAM, the modulating signal modulates the carrier pulse amplitude. As mentioned here amplitude of train of high frequency carrier is varied in accordance with the sampled values of message signal.

In this modulation type, message information is encoded in amplitude of series of signal pulses at modulation side. The demodulation is carried out by detecting amplitude level of carrier at every symbol period. PAM
Fig.1 PAM

The figure depicts time domain representation of the PAM technique which mentions analog message signal and PAM modulated signal as output.

PWM

The PWM signal is a pulse signal which pulse width is proportional to the amplitude of the modulating analog signal.

PWM
Fig.2 PWM

The figure depicts time domain representation of the PWM. One of the application of PWM is in speed control of the DC motor.

PPM

The PPM signal is a pulse signal which pulse position is proportional to the amplitude of the modulating signal amplitude. The time domain representation of PPM is mentioned in the figure.

PPM
Fig.3 PPM

555 Timer IC is most popular to generate waveforms for PPM and PWM modes. PWM is generated using 555 timer in monostable multivibrator mode. PPM is generated using 555 timer by using PWM as a trigger signal in monostable multivibrator mode.

The following table summarizes difference between PAM, PWM and PPM.

Method B.W. Power Efficiency(SNR) Complexity
PAM Less Lowest Lowest
PWM High Moderate Moderate
PPM High Highest Highest

Refer advantages and disadvantages of PAM, PWM and PPM modulation types.

Modulation types

BPSK -This page describes BPSK modulation technique with equation and constellation diagram.
QPSK -This page describes QPSK modulation technique with equation and constellation diagram.
QAM-This page describes QAM modulation technique with equation and constellation diagram.
MSK-GMSK MSK modulation,GMSK modulation and GMSK demodulation.
8PSK 8-PSK modulation or multilevel PSK or phase shift keying modulation technique.
BPSK vs QPSK -Difference Between BPSK and QPSK modulation techniques.
QPSK vs OQPSK vs pi/4QPSK-Difference between QPSK,OQPSK and pi/4QPSK modulation techniques
Differential Encoder and Decoder

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CDMA vs GSM
Bluetooth vs zigbee

RF and Wireless Terminologies


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