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# PBRS

(joined March 2015)
Participant

hi all,

i want to know there is option of setting bits:

1. order(???)
2.alternate(i.e alternate zeros and ones)
so on

what do order and other option means.
with regards

### Responses (18):

• #30763
aasif bashir dar
Participant

hi all,

i want to know there is option of setting bits:

1. order(???)
2.alternate(i.e alternate zeros and ones)
so on

what do order and other option means.
with regards

• #30776
alistu
Participant

Hi Aasif,

I believe “order” is used to set the length of the sequence that is generated by this component, and it reads sequence length information from layout parameters in script mode. If “Alternate” operation mode is chosen, an alternate sequence of ones and zeros is generated by PRBS generator.

Regards

• #30792
Aabid Baba
Participant

Hello Asif,
You can infer from the meaning of order itself , it is nothing but defines the the order of sequence length in which the bits are transmitted.
I agree with Alistu , it must read the sequence length from the layout parameters in script mode only.
And as far as Alternate operation mode is concerned , it describes the scene about arrangement of sequence in terms of alternate zeroes and ones that we receive from the pseudorandom binary sequence generator.

Regards

+17
• #30806
aasif bashir dar
Participant

hi alistu,

order , alternate, probability, ones, zeros…. they all are options in one parameter in the PBRS component under the name operation mode.

if i select ORDER option, the sequence of bits is different from that of alternate and probability.

i understand all of options among them, but have confusion regarding ORDER, AND probability.

with regards

• #30827
alistu
Participant

Hi Aasif,

The ones and zeros in the sequence are chosen with a probability as you know. Now when the probability mode is chosen, the “mark probability” option becomes available. Any number that is chosen between zero and one indicates the probability of ones generated in the output bit sequence of the component.

Regards

• #30838
aasif bashir dar
Participant

hi alistu ,
but iam not still able to clear the logic behind the option “order”.

i further want to know that how could i select my own user defined sequence say 10101111011101,instead of the pseudo-random sequence. how can dothat at the transmitter end.

with regards

• #30860
alistu
Participant

Hi Aasif,

I believe the user defined bit sequence has been well explained by Naazira. The order in mathematics is the power of a number. For example, in the equation 2^6=64 , the order of 2^6 is 6. Here in PRBS generator, the sequence length is produced as 2^k, where k is the order and has to be determined.

regards

• #30853
Participant

Hi Aasif..
Well you can always have your own defined bit sequence.
Select User-defined bit sequence generator from the library. Then in the option ‘bit sequence’, you can enter the sequence you want.
Hope this is what you meant to ask.

Regards.

+1
• #30856
aasif bashir dar
Participant

hi naazira,

• #30863
aasif bashir dar
Participant

hi alistu and naazira,
i appreciate both of for your valuable suggestion.
for simulation purposes, which option among order, alternate, probabilty must be choosen, so that results after simulation can be applied to practical scenario.
with regards

• #30866
alistu
Participant

You’re welcome Aasif. In practice, the number of ones and zeros is usually considered the same, since this is a more random behavior for the input data, so probability would better not be other than 0.5. Also, the place of zeros and ones is random, so alternate option is not necessary. So I’d go with “order”, which is the default mode.

Regards

• #30868
aasif bashir dar
Participant

hi all,
thanks alistu for your simple and easy explanation. i was also using ‘order ‘ as my option in PBRS gennerator,and i wanted to be sure what those terms mean, and i am doing my design correct.
i appreciate responses of all .

with regards

• #31016
alistu
Participant

You’re welcome Aasif. The “order” option cannot be accessed unless the “order” option is chosen in operation mode. I still have doubts about one thing, though. When the order option is not chosen, how the lengt of the sequence is calculated. We know the length should be given from layout parameters, but how?

Regards

• #30902
Participant

Hi Aasif..
Are you talking about the parameter ‘order’ where in a logarithmic formula is written ?

Regards.

+1
• #30908
aasif bashir dar
Participant

hi naaazira,
in pseudo random sequence(PBRS) gennerator component of optisystem , you can check the component properties.by default there is OPERATION MODE set to ORDER in main parameters.
just beneat that there is logarithmic formula is written.

with regards

• #30912
Participant

Okay Aasif, I’ll check it and let you know.

Regards.

• #30919
aasif bashir dar
Participant

hi naazira,

you are welcome

• #31604
Ranjeet Kumar
Participant

sir,
It is a pseudo random bit generators as it name suggest we can’t set bits. its bits order is random only its order, probability, alternate, ones and zeroes will be changed.

• #31796
aasif bashir dar
Participant

hi ranjeet,

please check all the comments above and my query.you will figure out what the real point of discussion was. still thanks for your reply

with regrds