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3 votes

Which is the correct equation for union bounds for non-standard QPSK?

It is important not to confuse the union bound with further assumptions and simplifications made to our calculation of the probability of error. The analysis starts with a constellation of only two ...
MBaz's user avatar
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3 votes

Which is the correct equation for union bounds for non-standard QPSK?

You are assuming $\textrm{Pr}\{s_2|s_0\} \ll \textrm{Pr}\{s_1|s_0\}$. However, it could be possible that $\textrm{Pr}\{s_2|s_0\} \approx \textrm{Pr}\{s_1|s_0\}$ when $0 < \beta \ll \alpha$. The ...
AlexTP's user avatar
  • 6,605
2 votes

spectral bandwidth of QPSK signal

Regardless of how $B$ is defined earlier in the Wikipedia article, the equation starting with where the Nyquist rate is introduced is a single-sided bandwidth: $$f_p < 2B$$ Which state that (single-...
Dan Boschen's user avatar
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1 vote
Accepted

What's wrong with 180 degree phase shift in QPSK?

OQPSK is used specifically to limit the peak-avg ratio of the QPSK waveform, as it avoids transitions from going through the origin. When the modulation in QPSK changes from one point in the ...
Dan Boschen's user avatar
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1 vote

BPSK decoding with a non-ideal transmission medium

It is not typical to transmit rectangular pulses as it results in a much wider spectrum than is necessary, resulting in poor spectrum efficiency and more susceptibility to group delay distortion ...
Dan Boschen's user avatar
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1 vote

How can a costas loop work when root raised cosine filter used on QPSK signal?

If time synch has been completed, confirm that the waveform has been put through a 2nd RRC filter and then down sampled to one sample per symbol. This should then be the ideal constellation with only ...
Dan Boschen's user avatar
  • 52.3k
1 vote
Accepted

QPSK demodulation carrier frequency offset compensation on python

The OP is correct that the constellation is spinning due to a frequency offset, and removing the phase versus time is the right direction to take (which is frequency offset given frequency is the time ...
Dan Boschen's user avatar
  • 52.3k
1 vote
Accepted

I/Q scatter plot of raised cosine filter in QPSK

This is likely due to a fractional timing offset as could be expected depending on the delay in the pulse sampling filter (likely a half sample offset if the filter was generated with an even number ...
Dan Boschen's user avatar
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1 vote
Accepted

How to choose sample offset values in timing synchronization for a QPSK demodulator?

The target offset is 0. This corresponds to zero timing error, and also has the highest slope (sensitivity) to a timing offset which is the ideal location to lock a loop. The Gardner using three ...
Dan Boschen's user avatar
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