distorted signal at user side

[jyoti raina]

hi evry1 plz have a look at this signal..i am designing a 4 channel wdm system..i initially hd problm with the signal after the mux bt the problm was solved bt nw my problm is at the filter m using at d receivr side…
i do nt get anthing clr frm this..i increased d power to c if anythng happens bt stil the signal is same..plz tel me what shud i do to get four wavelengths vth sme power level..
thanx in advance

Attachments:

1. 

   project.jpg
   

[aasif bashir dar]

hi jyoti raina,

looks like you are getting power at only 193.1thz and for other wavelengths the power is very less…but jyoti you have not mentaoned the type of filter you are using at the rx end… pls expalin it bit further,.

with regards

[jyoti raina]

hi aasif sir…yes i gt signal at only one freq.. i m using L.P bessel filter..plz help

[SAHIL SINGH]

hi jyoti raina,

I agree with aasif bashir’s point of view that you may be getting power at only 193.1thz and for other wavelengths the power may be very less…Please specify the type of filter you are using at the receiver end.. By specifying this information the other members on the forum may be able to provide some suggestions which may help you…

with regards
Sahil Singh

[burhan num mina llah]

Hi jyoti raina

Please upload the .osd file of your model and also provide the screenshot of the filter properties you have kept for your design.. That would help us get the better insight of your problem and we may be able to give you some better suggestions to improve your results and get a better spectrum as would be required by you..

Regards

Burhan

[jyoti raina]

helo burhan mam.. am using the 32 channel wdm model in optiststem examples..i hv changes channel no to 4 fr my btech project. plz check dat

[umer syed]

hi jyoti raina
I agree with aasif bashir and sahil singhs point of view that you may be getting power at only 193.1thz and for other wavelengths the power may be very less…Please specify the type of filter you are using at the receiver end.. By specifying this information the other members on the forum may be able to provide some suggestions which may help you.
please upload the .osd file of your model and also provide the screenshot of the filter properties you have kept for your design so that we
can better understand your proplem.
with regards
umer syed

[jyoti raina]

helo umer sir…i am using low pass bessel filter at the Rx end.. for osd file i mentioned in abv comment..check thr.

[ZULKARNAIN]

hi jyoti raina…
as clear from the screen shot it is clear that you are getting signal only in the lower region that means the filter is only passing that much band and i think increasing power will not help you in this. Also you have not mentioned the type of filter your are using in your design and i think the filetr you have used has aa very narrow passband. so you sholud try to use a filter with a wider passband.
with regards

[Atul Sharma]

greetings all.

[jyoti raina]

hi zulkarnain sir…i hv tried bt stil same response..n i m using low pass bessel filtr..its nt narrow band filtr i suppose.

[SAHIL SINGH]

hI Jyoti Raina,

It has rightly been pointed out by Zulqarnain that from the screen shot it is clear that you are getting signal only in the lower region which can be interpreted that the filter is only passing that much band… i also think that increasing the power in this case will help you much… Hope you get my point..

Regards
Sahil Singh

[Atul Sharma]

Hello Jyoti Sharma. Greetings.

Well here i agree with Burhan. It will be easier to guess your problem if you try to upload your osd file. i think you may be doing something wrong after the Mux. Can you Share the snapshot of your signal waveform after the Mux may be that would help. However the problem which you are facing may be because of the high launching power itself. Try increasing the order of the filter and check out the results. I hope you get your issue resolved.

Regards
Atul Sharma

[jyoti raina]

helo atul sir..i tried to vary thz parameters bt stil no help..for osd plz refer to abv reply to burhan mam’s reply. thnx anyway

[SAHIL SINGH]

Hi Jyoti Sharma,

You are right… Very nicely explained… Thanks for taking your time to get my query resolved…

Regards
Sahil Singh

[Aabid Baba]

Hello Jyoti,
As other members have mentioned that it will be convenient if you upload the .osd file. And yes which filter are you using and what order?
Regards

[burhan num mina llah]

Hi jyoti raina

I have posed a similar query in regards to DWDM system that i was facing. I suggest you to go through the suggestion dhiman kakati has suggested. May be you also would get some idea about your project. I don’t if it will help or not as i myself didn’t implement it yet. Still just have a look. Here i am posting the link of topic..

DWDM system

Regards

Burhan

[Ranjeet Kumar]

Hi jyoti,
From your attachments it is clear that you are 4 channels with frequencies 193.1 thz, 193.2 thz, 193.3 thz and 193.4 thz.
But the problem is that 193.1 thz frequency channel is the most dominant one with large amplitude as compared to left.
I think you should check the lase power in dbm of all the laser you have used in your design, because according to me the you have set the power of laser of frequency 193.1 thz has more power than others . hence output is also greater than others.
Hope this will help you.
Seeking your response.

[Dr. Dhiman Kakati]

Hello Jyoti Raina,
For what purpose you are using low pass filter at the receiver side, I think you should try using Band pass filter if you want to use at the input of the demodulator.
The other signal power is getting lost because you are not putting the required frequency in the LPF and there may be some misconception about your implementation of low pass filter frequency. Please have a look once again.

Regards,
Dhiman

[varinder singh]

hi jyoti raina ….
i agree with all previous view points that you are getting signal only in the lower region.you should firstly mention the type of filter you are using so that somebody can help you in this matter.
with regrads

[Ubaid Bhat]

hi jyoti raina..
i agree with everyone suggestions above that it may be an issue with your filter.I also think that there is some issue with your filter as it is not passing all the frequency of the system you have designed. So you should try to use a filter that have atleast that much of passband which you require in your design.
hope you got my point.
with regards

[varinder singh]

hi jyoti raina,
if you didnt get clear signal at the output of the recevier..then i think you should use bessel filters or otherwise use repeaters………..

[Naazira Badar]

Well Jyoti Sharma..

Could be more clear with your query. what exacly is the issue with your system? Since WDM MUX/DEMUX have filters, the output channels are bound to have different power levels as long as some explicit power control circuitry is not used.
As going by the image shot you have attached, i think it is some design error. please post your osd or screenshot.

Regards
Naazira Badar.

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