QPSK Demodulation with Single Photodetector

[Essam Berikaa]

Hi,

I would like to know if I can demodulate a QPSK signal with a single photodetector or down-conversion mixer?

[Ahmad Atieh]

Hello Essam,

You need to use four PDs in the receiver to extract the information of the modulated received QPSK signal as shown in the attached file. There is amplitude and phase information that you need to extract, which can’t be obtained using a single detector because it is a square law device.
Regards,
Ahmad

Attachments:

1. 

   QPSK-System.png
   

[Essam Berikaa]

Hello Dr. Ahmad,

Thank you so much for replying to my inquiry; however, I am still confused and I have emailed you the detailed description of my question.

Generally, I would like to know how some papers decode QPSK or QAM signal with real-time oscilloscope after down-conversion to the baseband or IF frequency.

[Ahmad Atieh]

Hello Essam,
I did reply to your email. Please check it.
Regards,
Ahmad

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