Search Results for 'DPSK'

[Tayyab MehmoodParticipant]

I post my problem in this thread because Hager had the same problem in the beginning of this thread.
I still did not figure it out whats wrong with the DPSK system.

Regards

[UMAR FAROOQParticipant]

Line width 0.2 MHz,Gain of amplifier 20 db,launched power 0 dbm. At ONU, a 3dB optical splitter divides downstream into two parts. An
intensity modulation technique of 10-Gbps OOK is used to re-modulate the first half of the power splitter to generate upstream data signal while the second half goes to DQPSK OR DPSK receiver.This re-modulation takes place by the received downstream signal which is either DPSK or DQPSK. I know its hard to understand but currently i am working on this project and it is not possible for me at this time to upload simulation.
just see my eye diagram and tell why one eye coincide with another eye as i have clear eye opening on up streaming side.

[UMAR FAROOQParticipant]

According to your suggestions i use optical amplifier and change the input power but my eye diagram remains same.Upstream eye diagram is fine but downstream eye diagram remains same when i use DQPSK at transmitter.When i use DPSK its all fine but reach is limited.

[Tayyab MehmoodParticipant]

After reading the whole topic on Radio over fiber system, I concluded that I have the same problem with my system. Although my system is a bit more simple than the above mentioned system was but I am not getting the desired results (BER=10^-12). currently the BER is 0.
system specifications: bit rate= 240 Mbps ; symbol rate= 120 Msps; bits per symbol= 2 bits;
frequency of first DPSK modulator is 0.7 GHz; frequency of second DPSK modulator is 1.5 GHz.
I am attaching the snapshot and the system file below.
Regards

Attachments:

1. 

   pix.png
   

1. improve-DPSK-BER.osd

[alistuParticipant]

Hi Dhiman,

Please choose the DPSK modulator component in OptiSystem and then see the properties. The first parameter you can see in the Main tab in the DPSK properties is “frequency”. This is what I have been referring to in my former post as the frequency of the carrier being available in the component.

Regards

[alistuParticipant]

Actually I couldn’t! And I have doubts about using threshold detectors that Debanjan has used for DPSK. So I asked about the result you have obtained and it is a normal thing in these forums. BTW, the decision component used was set for BPSK, so I changed it to PSK with 3 bits per symbol on differential coding and yet did not manage to get results.

Regards

[Debanjan Sarkar]

Hi all
I have implemented DPSK in SCM from the example as given in example for ASK.
But I am not getting the output. Please share your knowledge and also find the attachment.
Thank you

Attachments:

1. dpskscm.osd

[alistuParticipant]

For PSK and QPSK, you can use the PSK coder and decoder. And for DPSK and DQPSK coding schemes you should use the DPSK coder and decoder in the OptiSystem library. In the OptiSystem sample files in the advanced modulations category also you can see the same procedure has been taken.

Regards

[Prarthana KashyapParticipant]

I need to be clear, suppose we are using four modulation schemes such as PSK, QPSK, DPSK, DQPSK so my question is for all the four modulation I have mentioned here the decoder will be same or different because all of them are phase shift keying only so can we use psk decoder for all the four.

Regards

[Roman IbragimovParticipant]

Do you have description for this figure. How many channels? It’s single channel or DWDM system. which is modulation format (NRZ, DPSK, QPSK, 16QAM, OFDM+QPSK)? How did you get this figure? from experiment?

[SashaParticipant]

Hello Ahmad,

I tried DPSK using electrical components and I am getting an output. Check whether this suits with your application.

Regards,
Sasha

Attachments:

1. dpsk.osd

[alistuParticipant]

Hi Dhiman,

The reason for my suggestion was to find a way to make this work in OptiSystem, not based on the theory. Please refer to the comment I have addressed below, where I have described more or less the same issue:

DPSK (BPSK) modulator using delay feedback

Regards

[Sanjeev kumar]

Hello everyone…
I would like to ask about MSK modulation and demodulation in Subcarrier multiplexing and i am not getting the results. so can anyone provide me the resolution to this. i have also SCM using DPSK even these results are not fruitful. the optical filter and electrical filter bandwidth is too confusing. i am also uploading the OSD file. please provide me the solution.
thanx in advance

Attachments:

1. SCM_MUX.osd

[Ahmad MahmoodParticipant]

Thanks alistu for your valuable reply 🙂
Actually I am not implementing any paper I am to generate a DPSK(BPSK) signal for Analog to digital conversion and then again convert it to analog and detect. This is my class project. I have used the builtin DPSK modulator present in Optisystem 13 for this purpose but after DAC conversion the signal loses its phase change. My supervisor suggest me to design my own DPSK modulator and demodulator for this purpose. Now I have made the circuit as you suggested but it dont show output after XNOR gate. I found the design at the site given below. My .osd file is also attached Kindly Help. Thanks

http://www.rfwireless-world.com/Terminology/DPSK.html

Attachments:

1. DPSK-Modulator.osd

[Taiwo Ambali AbiolaParticipant]

First of all, you are welcome to the forum the same way I would equally welcome myself after a long break due to a number of task at hand. Just as Lalit Verma has already said, the forum is more of a way to implement your design using optisystem softwares and some others. There are some factors you need to consider when talking about SAC-OCDMA. One is how many users, which light source do you want to use (LED or multi-wavelenght laser,white light), which code do you plan to use, (eg, OOC, MQC, KS, MS code) and also the decoding techniques you have chosen to use.

Whichever way, You have the light source (example LED), the spliter(divide into number of users), the FBG to implement the chosen code, modulator to modulate the light using the bit sequence from the PRBS with a specific modulation format ( such as NRZ, RZ, and other advance modulation formats such as QPSK, DPSK etc). Then you need a power combiner/coupler to couple the signal from different users. then you select your channel of communication (free space optics (FSO) or fiber). At the receiver, you equally need a splitter, to divide the combined signals into the number of receivers. Then you apply your chosen decoding techniques e.g(direct decoding, complementary, AND decoding or any other you have chosen). after selecting the decoding measure, you need a photodetector (to convert to electrical signal), low pass filter (to remove noise) and also BER analyzer (which gives you error rate by comparing your received signal with the transmitted one, then gives you the rate of error in your system. If you can recollect, A minimum BER of 10^-9 and below e.g (10^-10, 10^-15, 10^-18, 10^-30 etc) is the standard for effective communication. You can modify the parameters to suit your design. I hope the explanation helps. Kindly signify if you need more help. There are professionals like Ravil, Samson, Optiwaves teams, and others to help with more information.