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phase shift with simrf

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seme
seme on 25 Nov 2013
Can anyone help on how can i use phaseshift block in simrf to shift the phase of the signal. For example if i want to shift the phase of sine function by 90 degree to get the inphase and quadrature components.
Thank you

Answers (2)

Giorgia Zucchelli
Giorgia Zucchelli on 26 Nov 2013
Hi,
I assume you are referring to the phase shift block of the Circuit Envelope library in SimRF. You can find an example of how to use the phase shift block in the shipping example "Architectural Design of a Low-IF Receiver System". In this case a 90 degrees phase shift is used to generate the LOs signals for the quadrature branches of the receiver and to implement an ideal Hartley receiver for low-IF image rejection.
The phase shift block applies a constant phase shift to all simulation frequencies.
From the MATLAB command window, to open the example type the command (or just look at the examples in the documentation):
>> web([docroot '/simrf/examples/architectural-design-of-a-low-if-receiver-system.html'])
With best regards,
Giorgia
  1 Comment
seme
seme on 26 Nov 2013
Hi Giorgia
I have checked the example and when I try the block it is not working. All I wanted is to shift sine wave in 90 degree, as follows sine wave --> 90 degree shift ---> cosine
I have used the input and outport,RF configuration in simrf library but it is not giving me a 90 degree shifted sine wave . Is there anything I should be changing.(I read that I have to use Hilbert Transform or on some papers but i don't want to use a frequency dependent phase shift for the moment. All I need is a 90 degree phase shift Thank you for your response,I really appreciate if you could help me figure out this. Thank you!!

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Giorgia Zucchelli
Giorgia Zucchelli on 9 Dec 2013
Hi,
Apologies for the late reply.
The SimRF phase shift block applies a rotation to the carrier frequency. For example, if you a have a real modulated signal applied to a non-zero center frequency, the phase shift block will rotate the signal and make it purely imaginary.
If you need to apply a phase rotation to the baseband signal you might want to use the phase/frequency offset block from Communications System Toolbox.
If your goal is instead to apply a phase rotation to both the envelope and the carrier, then you need to use both blocks. If you want to model a time-domain delay, you need to apply a time-domain delay to the envelope and an equivalent phase rotation to the carrier. I attached an example hoping that will help in answering your question.
With best regards,
Giorgia

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