Search Results for 'loop control'

[Joseph JiangParticipant]

Ravil，the reason why I use the bidirectional fiber rather than unidirectional is that i want to add the effect of double rayleigth SCATTERING to my system.however,it occurs to error when i use a bidirectional fiber especially when it is a short distance. I wander if it is a error use loop control when i add a bidirectional fiber.thank you!

[RavilParticipant]

Hi Joseph,

Sorry for my late reply… You can definitely use a loop control with a bidirectional fiber from the theoretical point of view. However, according to your attached scheme (by the way, is it your final version with all modifications you mentioned above?), I am not exactly sure how you are implementing this bidirectional connection, i.e. at each side of your scheme you have only one transmitter or receiver. Can you explain it to me briefly?

[Joseph JiangParticipant]

Thank you，RAVIL!i just want to know is it right for my use with loop control and bidirectional fiber.There is anther question about the version 7.0 of optisystem.i find that the bit sequence length and samples per bit should not be more than 512bit and 64 samples per bit.if not ,it occurs to error.i want to know why it happens?thank you!

[Joseph JiangParticipant]

hi,RAVIL,Thank you for your reply!the bit rate of my project is 100MBps.I just want to know why it ocurrs to error when i use the device loop control.as far as i know,the example use of loop control is unidirectional fiber rather than bidirectional fiber.i just want to know is it right for my use with loop control and bidirectional fiber.thank you!

[Joseph Jiang]

hello everyone，i use a loop control to simulate a long distance system.however it occurs to a error.I use a bidirectional optic-fiber.can anybody give me a help?thank you in advance!

[Heitor GalvaoParticipant]

Thanks Damian, remarks now change the frequency of 151.1 THz to 191.2 THz and really I could see better, now the signal is propagating in the fiber, but not get out of the first loop, if I put two laps in the control loop for example. You can check please

[Heitor Galvao]

The orthogonal multiple optical carrier generator, also known as optical comb generator (comb geradoróptico-OCG), is the basic cell of the optical transmitter systems (Coherent-WDM-Co-WDM). This generator is formed by a single laser and a ring of recirculation.This ring, in which are generated several carriers, consists of: a 2 x 2 optical coupler; a Mach-Zehnder optical modulator of type double, which has the function of generating a signal, a single optical amplifier (Erbium doped fiber-EDFA amplification), which compensates for the losses in the ring and an optical filter, which limits the number of carriers generated.
In: optisystem
Global parameters to insert a variable int, which will determine the number of turns in the control loop, the optical filter placed a bandwidth of 800 Ghz band, i.e. the signal will generate eight carriers spaced de100GHz, IE, which will determine the espacamento of my suffering is the RF generator, sine is 100GHzin laser twowho are connected to power combinner193.1 THz arises, namely, I have eight years to 193.1 THz to 193.8 THz, equivalent to WDM transmitter, optical filter, put a date value by method that attempts to limit estevalor the number of carriers generated.

More so when you replace the transmister WDM for optical generation comb, the values of OSNR and revou (BER) for the two networks with transmitters with different, more maintained the same characteristic of the two networks, dao not equal results. The optical generation comb is working only for channels 193.2-193.9 THz. I think some fixes can be made, but I don’t think opente WDM transmission and frequency would give the exact same results, because you are modulating umasequência with multiple frequencies where as WDM has distinguished different channels because they are different transmission schemes.

I found a palette in the archives of optisystem 13, “WDM Optical coherent detection OFDM system” there is a way to adapt your modulator and receiver my comb ópticotransmissor generation? Because as you can read in this scholarly reference uses ofdm: http://www6.univali.br/seer/index.php/acotb/article/viewFile/6226/348

[Heitor GalvaoParticipant]

Good afternoon I’m with a doubt relevant Damian who is as follows: when I put a WDM analyzer after the loop control (fiber + amplifier), there are acceptable values of OSNR, more so that there is a but if placed a WDM analyzer in the first channel for example the demultiplexer he will give a value apoximado with WDM anaylzer placed in control loopI understand that the values are equal, is there any kind of loss to give such a difference in values of OSNR? In the annex you see the table regarding the WDM analyzer placed in the control loop, and the right of the WDM table corresponds to the WDM placed on the first channel of the demultiplexer.

[Damian MarekParticipant]

Hey Heitor,

1) A back to back transmission scheme describes a system where the receiver and transceiver are directly connected with no transmission link. As an example in your attached file, everything inside the loop control would be disabled.

2) I’ll also respond to your private message about the frequency comb project. I’ve modified it in the attached project file to a back to back system. You can either delete the fiber, amplifiers and dispersion compensating fibers or you can directly disable the component in the Simulation tab of the components. I fixed your project file by modifying the receiver. The channels were actually 193.2-193.9 and the cutoff frequency was set in terms of the symbol rate, which should have been 10 Gb/s

Regards

[Heitor Galvao]

The optisystem provides a tutorial file, with the control loop that includes the optical fiber and an amplifier, how do I plot the graph of BER vs OSNR for each channel demultiplexer eight ports?

[Abdallah Ismail]

Dear,
I’m designing a system that have Loop Control with 8 and connected to measured index MMf and amplifier and BPF,the amplifier generate noise but the measured index MMf produce errors because the noise bins in an input to it.
I tried to enable “convert noise bins” in the global parameters but the same error still appear.
error message “Invalid Input signal,Noise bins are detected at the input”
can anyone help me to solve the problem.

[Abdallah IsmailParticipant]

Dear Damian,
I removed the loop control and the error still appear in the mode selector.
Can you check?

Regards,
Abdallah

[Damian MarekParticipant]

Hi Abdallah,

Ok this problem was a little more confusing than I thought. It can simply be solved by removing the loop control.

The long explanation is that noise bins are being generated in the loop and being fed back into the input of the measured multimode fiber, which doesn’t accept noise bins. This is what was giving the error to me. I didn’t see any problem with the mode selector.

Regards

[Damian MarekParticipant]

Please find the attached files.

For the “Dispersion compensation pre post symmetrical.osd” example, when we compare the performance of NRZ and RZ, we normally set the input power of the fiber (launch power) to be the same. NRZ and RZ signals have different modulation efficiencies. Therefore, the modulated signals has different powers. My suggestion is adding an optical amplifier after the modulator and before the loop control, and set the power for both cases to be the same, as shown in the attached osd files. For the same launch power, RZ has a better performance than NRZ.

By the way RZ signal has a wider bandwidth than NRZ signal, therefore the bandwidth of the filter should be different for different cases.

[Damian MarekParticipant]

Answer:

It is often difficult to experiment on long fiber lengths in a lab setting. Usually a lab will perform the experiment on a shorter length fiber, but loop the signal through multiple times. This is performed using a loop control.

In OptiSystem, the component Loop Control performs this function. You can learn more, by following the tutorial at:

Lesson 3: Optical Systems WDM Design