The qpsk tag has no wiki summary.
2
votes
1answer
169 views
Apply AWGN noise to QPSK-OFDM symbol
I'm working on an OFDM-QPSK based system and I'm having some trouble to match the BER of my system with the theoretical curve. My OFDM implementation fills all the subcarriers and have t_symbol s ...
3
votes
1answer
340 views
How to perform carrier phase recovery in software?
What are the options for recovering the phase of a BPSK signal in software? The only resources I can find online contain circuit diagrams – there seems to be no one willing to explain this to people ...
1
vote
1answer
73 views
Why is a precoder necessary for DQPSK and what does it accomplish?
I've implemented a soft-decoder for DQPSK using the wonderful answers I received here:
How to soft decode DQPSK?
To get the soft-decoder working properly I needed to precode the data I was sending ...
4
votes
2answers
167 views
How to soft decode DQPSK?
I'm successfully soft-decoding D-BPSK by taking the dot-product of the constellation-position of the symbol and of the previous symbol. If the result is >= 1, then the symbol phase hasn't changed and ...
2
votes
1answer
176 views
Why does OFDM use cyclic-prefix while QPSK uses root-raised cosine filters?
My understanding is that BPSK/QPSK/... are often implemented with root-raised cosine (RRC) filters to reduce ISI and bandwidth.
OFDM can be understood to be BPSK/QPSK/... implemented on multiple ...
0
votes
1answer
84 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 ...
1
vote
2answers
322 views
Why do you get instantaneous phase by calculating correlation with a carrier signal?
I am somewhat new to DSP. I'm trying to implement BPSK by following this Python QAM tutorial.
My code seems to work, but I really just ported the tutorial's Python code to C++, and do not understand ...
1
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2answers
1k views
0
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0answers
232 views
What is the practical difference between Linear and Non Linear Modulation Techniques
What is the practical difference between Linear and Non Linear Modulation Techniques ?
M ary Psk and M ary Qam are examples of linear modulation, However they are different from each other in such a ...
3
votes
0answers
72 views
Recovering signal for psk
I am currently working on a product(cant disclose too much details of the actual project) in which some data is being sent via audible(but on the higher freq) sound that is encoded with dqpsk.
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5
votes
1answer
2k views
Matlab plot of QPSK system doesn't agree perfectly with theoretical BER curves
Does anyone know if there is a simple explanation on the fact that the theoretical bit-error rate (BER) curves of a Quadrature phase-shift keying (QPSK) system are approximately 1 dB shifted from the ...
