Hi everyone,
i’m currently trying to create a offset QPSK modulation using an MSK with a half-sine matched filter. This is based on the IEEE paper https://ieeexplore.ieee.org/document/4102435. I generated an OQPSK and MSK signal with MATLAB and plotted the angle of the signal. Both can be seen below. There is no frequency error or noise. They spectrum for both is the same and the amplitude of the symbol stays constant, so this is indeed a OQPSK signal. Just the resulting bits are different.
I can demodulated the OQPSK using the OQPSK demodulation function from the Communications Toolbox as well as the with the symbol order based on the phase seen in the picture. So the OQPSK is correct. I can also demodulate the MSK with a normal FSK demodulater and the ouput is the same as with the OQPSK. But when applying any kinf of OQPSK demodulation to the MSK signal the resulting sequence is different as well as the phase (picture).
So is a MSK with Half-Sine Filter really equivalent to an OQPSK and both can be received with the same receiver?

This is the phase of the MSK signal

And this is the phase of the OQPSK signal

Best Regards,
AxelHi everyone,
i’m currently trying to create a offset QPSK modulation using an MSK with a half-sine matched filter. This is based on the IEEE paper https://ieeexplore.ieee.org/document/4102435. I generated an OQPSK and MSK signal with MATLAB and plotted the angle of the signal. Both can be seen below. There is no frequency error or noise. They spectrum for both is the same and the amplitude of the symbol stays constant, so this is indeed a OQPSK signal. Just the resulting bits are different.
I can demodulated the OQPSK using the OQPSK demodulation function from the Communications Toolbox as well as the with the symbol order based on the phase seen in the picture. So the OQPSK is correct. I can also demodulate the MSK with a normal FSK demodulater and the ouput is the same as with the OQPSK. But when applying any kinf of OQPSK demodulation to the MSK signal the resulting sequence is different as well as the phase (picture).
So is a MSK with Half-Sine Filter really equivalent to an OQPSK and both can be received with the same receiver?

This is the phase of the MSK signal

And this is the phase of the OQPSK signal

Best Regards,
Axel Hi everyone,
i’m currently trying to create a offset QPSK modulation using an MSK with a half-sine matched filter. This is based on the IEEE paper https://ieeexplore.ieee.org/document/4102435. I generated an OQPSK and MSK signal with MATLAB and plotted the angle of the signal. Both can be seen below. There is no frequency error or noise. They spectrum for both is the same and the amplitude of the symbol stays constant, so this is indeed a OQPSK signal. Just the resulting bits are different.
I can demodulated the OQPSK using the OQPSK demodulation function from the Communications Toolbox as well as the with the symbol order based on the phase seen in the picture. So the OQPSK is correct. I can also demodulate the MSK with a normal FSK demodulater and the ouput is the same as with the OQPSK. But when applying any kinf of OQPSK demodulation to the MSK signal the resulting sequence is different as well as the phase (picture).
So is a MSK with Half-Sine Filter really equivalent to an OQPSK and both can be received with the same receiver?

This is the phase of the MSK signal

And this is the phase of the OQPSK signal

Best Regards,
Axel msk, oqpsk MATLAB Answers — New Questions

​