BER analyzer

[Ranjeet Kumar]

Hi,

Can anybody explain What is threshold in BER analyzer.
And how it varies for different design.
here i am uploading image.

Attachments:

1. 

   Capture3.jpg
   

[alistu]

Hi Ranjeet,

The threshold is the value based on the received bits level compared to which the bit is detected. If the received bit amplitude is less than the threshold, the bit is detected as a logic “0”, and if the bit amplitude exceeds that of the threshold, the bit is detected as a logic “1”.

Regards

[Aabid Baba]

Hi ranjeet,
For this you can make it analogous to operation of a simple digital switch. Alsitu rightly mentioned about the detection. If the received bit amplitude is below the threshold, the bit is detected as a logic “0”, and if the bit amplitude exceeds the threshold, the bit is detected as a logic “1”. I hope it helps.
Regards

[aasif bashir dar]

hi ranjeet,
threshold is very essential parameter to be set in the tranmission channel.

if threshold is smaller, then there is great possiblity of heaving eerors in system because of noise power greater than threshold.

if threshold is larger, there is possibility of loss of bits(i.e again error) in reception, because bit power can be less than threshold becauese of channel attenuation.

thus threshold is to be optimized for minimum BER.

with regards

[Ranjeet Kumar]

Thank you all,
But we could set threshold value. Which parameters decide what should be the value of threshold and how it varies.

[umer syed]

HI RANJEET,
I THINK IT IS VERY MUCH VALID QUESTION AND COULD CONCEPT OF SETTING THE THRESHOLD FOR THE BER ANALYSIS

I GUESS WE COULD NOT SET THE THRESHOLD FOR BIT ERROR RATE ANALYSIS, THE THRESHOLD IS SET INHERENLTY BY THE ber ANALYZER.

WITH REGARDS

[Aabid Baba]

Hi Umer syed,
I could not understand your statement above. Do you mean we could set threshold for BER analysis ??
I guess it has to do with various parameters. Actually i have to design a threshold module myself for controlling power levels. I thought of asking you.
Regards

[Ranjeet Kumar]

thank you Umar sir for supporting and considering my problem and query.

[SAHIL SINGH]

hi..
The threshold is the value based on the received bits level compared to which the bit is detected. If the received bit amplitude is less than the threshold, the bit is detected as a logic “0”, and if the bit amplitude exceeds that of the threshold, the bit is detected as a logic “1”.
but i also agree with naazira because the bits are taken to be equi-probable. i.e, bits 0 and 1 have equal probability of being transmitted

[aasif bashir dar]

hi aabid,
in your comment of #32066, you are intermingling the this post query and your power threshold query of your.
and how does the threshold varies with different parameters. can we set it??
hope you will reply soon.

with regards

[Aabid Baba]

Hi aasif,
I guess you are not understanding the context in which i had mentioned it. I have used interrogative marks at the end of the statement that means i am asking it not stating it and if you are confused then let me put it this way for you , Which parameters decide what should be the value of threshold ???
Who does calculate the threshold value here??
I hope you got my point now.. I hope you will reply..
Regards

[burhan num mina llah]

Hi All

Aabid i also believe that your problem of designing the component to allow certain power levels above or below the threshold is different from what Ranjeet is asking, He wants to enquire about how to set threshold for the BER analyzer. I hope i had understood it correctly. As far as what Ranjeet is asking i am attaching a link below i hope u get to know how to set threshold as it shows how to calculate BER using a test set. And Aabid in your case u have to design a component as a whole i believe.

BER Calculation Using the BER Test Set

Best Regards

Burhan

[Aabid Baba]

hello Burhan num mina llah,
Thanks for replying. I understood what you are exactly referring to and rightly so. I was just asking if i could.
regards

[Naazira Badar]

Hi All..
Well threshold is no doubt a general concept.
But for the case of BER in communication theory, I beleive it is taken to be a mid-point , because the bits are taken to be equi-probable. i.e, bits 0 and 1 have equal probability of being transmitted. And at the Rx, if the amplitude is above mid-point, it is considered as 1 and if it is less than the mid-point value, it is considered as 0.

And For Ranjeet, I would suggest you to post a screenshot of the BER Analyzer results where in there is some value. In the image you have attached, no data has been received or atleast detected. So not much can be inferred about how Optisystem has programmed the BER Analysis.

Regards.

[Ranjeet Kumar]

Hi Naazira ma’m,
Here i am uploading the screenshots of BER analyzer with different values of Q-factor, Min. BER and others parameters as per your suggestions.
Now it would be easy to explain it further so that i could understand it better.

Attachments:

1. 

   1Capture.jpg
   

2. 

   Capture10.jpg
   

[Mohamed Ben zegalam]

Hi Ranjeet,

for the Capture10, as I can see the Q-factor is not mach the BER, please may you change the algorithm parameter to Gaussian instead of measuring. I think this will make the Q-factor mach the BER.

Thanks!

[burhan num mina llah]

Hello Aabid Baba

you are welcome. Productive discussions are always appreciated and discussion are overall productive i believe.
Ranjeet it seems to show the threshold values. Are u trying to ask that u want to edit this threshold value. then i believe it cannot be set in BER analyzer but it would be possible in the component ahead of that.

Regards

Burhan

[Naazira Badar]

Hi Ranjeet..

I appreciate that you uploaded these. Going by these images, I think the concept of having a midpoint threshold value is actually about the last option of the table ‘Decision Inst.’. And about the threshold value, I can see there’s a difference in the two imaged. I believe this has to do with adaptive thresholding, wherein going by the channel state the threshold values are set to minimise the BER. This varies with the modulation schemes as well. Eg. OOK has fixed point thresholding. Could you please tell me which modulation scheme has been employed in the system ?

Regards.

[Ranjeet Kumar]

Hi Naazira Ma’m
The above image(10) is the screenshots of 4 user unidirectional OFDM system. The Ber analyzer shows its values of different parameters in downlink direction.
I have little idea about adaptive thresholding, Decision Inst. and the channel state the threshold values are set to minimise the BER.
If possible please explain the above points further or post links to explain it.
seeking for your response.
thank you

[Ranjeet Kumar]

Hi Naazira Ma’m
The above image(10) is the screenshots of 4 user unidirectional OFDM PON system. The Ber analyzer shows its values of different parameters in downlink direction.
Here i am uploading the osd file of corresponding image and now expect some explanation from your side.
Seeking for your response.

Attachments:

1. OFDM-PON9.osd

[MHD NA]

you can make it analogous to operation of a simple digital switch. Alsitu rightly mentioned about the detection. If the received bit amplitude is below the threshold, the bit is detected as a logic “0”, and if the bit amplitude exceeds the threshold, the bit is detected as a logic “1”. I hope it helps.

[MHD NA]

threshold is no doubt a general concept.
But for the case of BER in communication theory, I beleive it is taken to be a mid-point , because the bits are taken to be equi-probable. i.e, bits 0 and 1 have equal probability of being transmitted. And at the Rx, if the amplitude is above mid-point, it is considered as 1 and if it is less than the mid-point value, it is considered as 0.
And For Ranjeet, I would suggest you to post a screenshot of the BER Analyzer results where in there is some value. In the image you have attached, no data has been received or atleast detected. So not much can be inferred about how Optisystem has programmed the BER Analysis.

[FAYIQA NAQSHBANDI]

HI MHD
As mentioned in the other post that plz avoid copying and pasting the same comments..try adding something which maybe helpful to other members…i hope u refrain from it..
Thanks and regards

[Manoj Kumar]

Hi All..
Well threshold is no doubt a general concept.
But for the case of BER in communication theory, I beleive it is taken to be a mid-point , because the bits are taken to be equi-probable. i.e, bits 0 and 1 have equal probability of being transmitted. And at the Rx, if the amplitude is above mid-point, it is considered as 1 and if it is less than the mid-point value, it is considered as 0.

And For Ranjeet, I would suggest you to post a screenshot of the BER Analyzer results where in there is some value. In the image you have attached, no data has been received or atleast detected. So not much can be inferred about how Optisystem has programmed the BER Analysis.

Regards

[Author]

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