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Pulse Interval Modulation-Advantages, disadvantages, comparison

This page describes Digital Pulse Interval Modulation (PIM) basics, PIM advantages and PIM disadvantages. It mentions comparison between PIM, PCM and PPM.

Introduction: As we know FSO (Free Space Optics) based solutions are used in fiber optic communication systems. Following pulse modulation schemes are employed which can provide higher average power efficiency at the expense of higher bandwidth requirement.
• On-OFF Keying (OOK)
• Pulse Position Modulation (PPM)
• Pulse Interval Modulation (PIM)

OOK Modulation

OOK modulation

It stands for On-Off Keying which is simple modulation scheme based on intensity modulation. In this scheme, '0' is indicated by zero intensity and '1' is indicated by positive intensity.
Refer difference between OOK vs ASK vs FSK >> for more information.

PPM Modulation

PPM modulation

As mentioned PPM is short form of Pulse Position Modulation in which relative position of pulse is proportional to amplitude of the modulating signal. It is similar to phase modulation (PM).
Refer advantages and disadvantages of pulse modulation schemes such as PAM vs PWM vs PPM >> for more information.

What is Pulse Interval Modulation (PIM)?

In this modulation scheme, data bits (in pairs) are encoded as number of time intervals between successive pulses as shown in the figure below.

PIM , Pulse Interval Modulation
Image Courtesy: slideplayer.com

The figure-1 depicts digital PIM (Pulse Interval Modulation) waveform. It also shows table with digital bit pairs and their pulse representations.

Benefits or advantages of Pulse Interval Modulation (PIM)

Following are the benefits or advantages of Pulse Interval Modulation (PIM):
➨It offers high APE (Average Power Efficiency) compare to OOK modulation.
➨There is no symbol level synchronization is required.
➨It offers high information capacity.
➨It offers simple receiver architecture.

Drawbacks or disadvantages of Pulse Interval Modulation (PIM)

Following are the drawbacks or disadvantages of Pulse Interval Modulation (PIM):
➨It has APE (Average Power Efficiency) lower than PPM modulation.

Comparison between PIM, PCM and PPM

Following points summarize comparison between PIM, PCM and PPM modulation types.
• PCM : In PCM, the analog speech waveform is sampled and converted directly into a multibit digital code by an Analog to Digital converter. In PCM samples are represented by digital binary form. Read more on advantages and disadvantages of PCM modulation >>.
• PPM : In PPM, relative position of pulse is proportional to amplitude of the modulating signal.
• PIM : In PIM, data bits (in pairs) are encoded as number of time intervals between successive pulses as shown in the table above.


Fiber Optic Network and Optical Components Related Links

DWDM system basics   Fibre optic communication   What is PDMA?   What is WDM?  SONET SDH tutorial   SDH Networks   SDH Frame structure   SDH Modulation   PDH Frame structure   Optical Components  Optical Isolator   Optical Circulator   Optical Amplifier   Optical Filter   Optical Coupler   Optical MUX DEMUX   Optical Equalizer   Optical Switch   Wavelength converter  

What is Difference between

PDH vs SDH  SONET versus SDH   CAS vs CCS  Types of WDM   Single vs multimode fiber  

RF and Wireless Terminologies


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