Linked Questions

2 votes
1 answer
24k views

what is the difference between QPSK and 4QAM? [duplicate]

i need to know the main difference between QPSK and 4QAM, i have searched over the internet and still i have not found a good explenation.
user24907's user avatar
  • 313
1 vote
1 answer
461 views

Binary and Quadrature Phase Shift Keying [duplicate]

I was learning Modulation Techniques and was on the topic Phase Shift Keying (PSK). As far as I have understood, In Binary PSK we encode a single bit on a one signal element and we differentiate ...
Abhijit Singh's user avatar
0 votes
1 answer
196 views

QPSK InPhase and Quadrature [duplicate]

I am new to DSP. Please bear with my question. In QPSK why are we multiplying InPhase (Odd Bit) with Cosine and Quadrature (Even Bit) with Sine wave in this QPSK formulae $$ s \left( t \right) = I \...
KJG's user avatar
  • 25
0 votes
1 answer
103 views

QPSK implementation with 2 BPSK [duplicate]

I have a tiny problem with understanding a thing here. for the 1st the phase shift is 0 degrees, so on its modulated wave we put 180-degree phase shift. for the 2nd 0, the oscillator puts a 90-degree ...
Jency's user avatar
  • 103
5 votes
1 answer
14k views

QPSK Modulation/Demodulation in C++

I'm trying to implement a QPSK Mod/DeMod system in C++. So far i have a bit generator that generates N bits and stores it into an array: ...
Brian's user avatar
  • 51
1 vote
2 answers
4k views

QPSK and OQPSK Modulation

In QPSK, after splitting the odd and even bits into the I and Q channels, and then multiplying them with the sine and cosine function, what next am I suppose to do? Do I rearrange them back into ...
Nazario_Jnr's user avatar
0 votes
3 answers
1k views

Processing OBPSK as OQPSK

I'm trying to create and process an OBPSK signal, which, as I understand it, transmits even bits on one axis and the odd bits on the opposite axis, resulting in a constellation with 4 unique points. ...
bruno617's user avatar
0 votes
3 answers
2k views

How can I generate offset QPSK symbols from QPSK symbols

I am trying to generate Offset-QPSK modulated symbols. But I am facing some difficulties. I know how to make QPSK symbols but I am unable to figure out at what stage I have to bring in changes to make ...
wanderer's user avatar
  • 151
1 vote
2 answers
2k views

Does gray coding bring improvement to SER of QPSK, compared with natural coding?

I understand gray coding contributes to BER of QPSK, yet really don't understand why it brings improvement to SER. According to the relationship of SER and BER, it should be improved. Actually, when ...
Palace W's user avatar
-1 votes
1 answer
1k views

difference between pi/4 qpsk and differential qpsk

What is the difference between a $\pi/4$-QPSK modulation and a QPSK differential modulation (DQPSK)? Are these modulations identical?
user35701's user avatar
0 votes
2 answers
1k views

M-Array DPSK decoding and encoding

So i'm trying to figure how how to do the encoding and decoding of an M-array Differential Phase Shift Keying (DPSK) signal. I understand how to do it for binary DPSK, but on higher ordered signals I'...
gerrgheiser's user avatar
2 votes
2 answers
965 views

Meaning of Q and I in all-software QPSK communication systems?

Q and I seem to come up a lot in discussions of digital communications, such as the comprehensive answer provided to this question: FFT window phase syncronising It seems like the Q and I channels ...
Dan Sandberg's user avatar
1 vote
2 answers
705 views

How are the constellation point coordinates determined in digital modulation

I need to understand where the concept of the distance comes from. What I mean is, how do we know what coordinates are to assign to points in the constellation. For example here for QPSK the points ...
Scavenger23's user avatar
1 vote
1 answer
1k views

Differential Encoding for M-PSK

Confused about a few topics w.r.t. differential encoding/decoding. First, consider the below BER curve taken from wikipedia ( https://en.wikipedia.org/wiki/Phase-shift_keying ) comparing BPSK/QPSK and ...
user67081's user avatar
  • 723
0 votes
1 answer
416 views

Phase shifts of QPSK

I'm honestly lost on creating timing diagrams for bit sequences. I understand for QPSK there are symbols 00, 01, 10, 11 with phase shifts of 45,135,225 and 315. I'm just not understanding how you ...
TheCoolest2's user avatar

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