coherent detection QPSK system

[Abhilash Achanta]

I simulated one of the OptiSystem sample file on ‘coherent detection QPSK system’.

After the simulation is done, the BER analyzer component shows Min BER = 1 (Please find screenshot attached)

Does this mean all the bits received have errors?

Attachments:

1. 

   QPSK.png
   

[Abhilash Achanta]

I have even observed in the tutorials section for QAM and DPSK.
The min BER is 1 which means there are 100 % errors in received bits?

Attachments:

1. 

   DPSK_eye_dia.png
   

2. 

   QAM_eye_dia.png
   

[Laksmi Juwita]

I wonder about the same thing. I run the DPQPSK coherent detection sample and get a 0 BER with 0 Q-Factor. If I’m not mistaken, the Q-Factor should be larger than 6. I’ll be waiting for a response on your question.
And so sorry that I cant help 🙂

[Aabid Baba]

Hello Abhilash,
You are right in saying that whenever BER is 1 it means all the bits transmitted are in error and this has to be a erroneous transmission. The bit error rate should be zero (ideal case) or close to zero for a realistic scenario. If Bit error rate is 1 , it signifies that the quality of reception is very bad and hence the receiver is receiving corrupted information. To this the quality factor will be eventually zero depicting poor reception of transmitted bits at the receiver.
I hope this is helpful to you. Thanking you.

Regards

[burhan num mina llah]

Hello Abhilash Achanta,

As far as your query is concerned i would agree with Aabid on this. It has been rightly mentioned that bit error rate 1 means the transmission quality is poor i.e corrupted information is being received which means the probability of error is maximum which is 100% in your case and as a result the Q-factor is also reduced to minimum value.
You may check various parameters of your design to set the bit error rate as low as possible. I hope you find it helpful.

Regards

Burhan

[Abhilash Achanta]

Hi burhan and aabid,

I’m just thinking how a OptiSytem sample file could give 100% error.
Sample files are supposed to give results close to practical values right?

[Aabid Baba]

Hello Abhilash,
I agree to that. May be you are doing something wrong. I suggest you to vary few design parameters and see if the results do get better.
Regards

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