Phase shift keying...

@neerajakshi-5usPZc • Oct 18, 2024

Oct 18, 2024

1.3K

i have a question related to digital communication.
what is the need of two sine waves in PSK? not only in PSK even in DPSK, FSK, and QPSK... if any one know the ans of my question pls ans.....

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[Prototype]

@prototype-G9Gn5k • Aug 29, 2012

What do you mean by two sine waves? Does these sine waves have some name to refer like modulating signal?
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neerajakshi

@neerajakshi-5usPZc • Aug 29, 2012

i mean the two sine waves which we get at the output of carrier generator which r in out of phase with each other....
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neerajakshi

@neerajakshi-5usPZc • Aug 29, 2012

and when comes to FSK these two signals have different frequencies....
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neerajakshi

@neerajakshi-5usPZc • Aug 29, 2012

i thnk u still dnt get me.refer the block diagram of bpsk
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[Prototype]

@prototype-G9Gn5k • Aug 29, 2012

neerajakshi
i mean the two sine waves which we get at the output of carrier generator which r in out of phase with each other....
Oh haha, well the answer is pretty simple. Two sine waves of two different phases are required for representing logic 1 & 0 respectively.

In FSK, again the same, some frequency X to represent logic 1 & other frequency Y to represent logic 0.
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neerajakshi

@neerajakshi-5usPZc • Aug 29, 2012

i/p is not always not in manner of 010101 . it may be 00000110001etc
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neerajakshi

@neerajakshi-5usPZc • Aug 29, 2012

u mean logic 1 or 0 of i/p data?
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[Prototype]

@prototype-G9Gn5k • Aug 29, 2012

neerajakshi
u mean logic 1 or 0 of i/p data?
Yups, for Logic 0 - It'll be some phase P1. For Logic 1 - It'll be 180 degree out of phase as of P1.

If you don't change the phase, you cannot distinguish between logic 0 & logic 1.

In case of FSK, you do this by having 2 different frequencies.

It doesn't matter the how's the sequence, if there are consecutive 0's then they will be represented by same phase (that's opted for representing logic 0) only.
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neerajakshi

@neerajakshi-5usPZc • Aug 29, 2012

ok can u tell me what is the use of NRZ-L coder in bpsk
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[Prototype]

@prototype-G9Gn5k • Aug 29, 2012

neerajakshi
ok can u tell me what is the use of NRZ-L coder in bpsk
NRZ aka Non returning to zero is an encoding technique. The signals are generally encoded in order to optimize the signal for sending it over the channel. Its adds few error detection capabilities as well.
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