Introducing a wideband analog alien wavelength into ONS 15454 system

Unanswered Question
Apr 23rd, 2009

I am working with an optical network provider in an effort to introduce several very wideband analog alien wavelengths into their network. The network is DWDM using a 50 GHz channel spacing and based on Cisco ONS 15454 equipment. The alien wavelengths would be generated by taking RF directly from a dish antenna pointed at a satellite. The signals could be several hundred MHz wide and centered as high as 18 GHz. This complex mix of signals (an entire set of transponders, each loaded with complex signals) will be injected directly into a fiber transmitter that is flat from 10 MHz to 18 GHz, and centered on an ITU grid frequency. My question is what will happen to this complex analog signal when it hits a Cisco transponder or other equipment in the signal path? It will probably look like wideband noise to any digital processing equipment in the path. Is there a way to bypass digital processing if this is an issue?

Thank you,

Juan Rivera

General Dynamics - AIS

I have this problem too.
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Marvin Rhoads Thu, 04/23/2009 - 13:35

I would bet the alien signals would be regarded as noise and effectively filtered out by the Cisco transponder(s). Your best bet would be to insert the signal after the Cisco gear hands it off to the outside plant fiver and extract it prior to the next site's input stage. That's the only way I can imagine "bypassing" the Cisco equipment (actually not encountering it at all).

You need to make sure that your injected signals are not stepping on the allocated ITU grid wavelengths being used by the Cisco transponders. That is, map out your frequency allocations to keep the signals separated in the optical domain.

juan.rivera@gd-... Thu, 04/23/2009 - 14:40

I think the Cisco transponders are in the middle of the path and not near either end. Is it possible to optically dmux those channels off the fiber, route them around the transponder and then mux them back in?

Marvin Rhoads Fri, 04/24/2009 - 04:42

It may be possible. You mentioned the existing infrastructure includes DWDM. How is that implemented? It's difficult to explain using text only, but one could possibly use a passive DWDM solution (like the Cisco ONS 15216 - see to pull out the ONS's signals, route them through the transponder(s) and then back onto the outside plant fiber.

viyuan700 Fri, 04/24/2009 - 06:00

Hi Juan,

Do you have info that what is this aliegn wavelngth which is centered around ITU grid and what wavelngth are you using in your 15454 grid? I think if the equipment which gives you alien wavelength around ITU grid can provide you a wavelngth whichyour Opticalnetworkprovider is not using. Only thing is that it also should have 50GHZ spacing.

My question is what will happen to this complex analog signal when it hits a Cisco transponder or other equipment in the signal path?

I have one more question here, is the alien wavelgth you are getting from Dish antenna is given in SDH format or is it some different format as explained in your message above?

Why i am asking this question is that signal Microwave antenna when converted to optical are changed in SDH /SONET format so that they can go over SONET/SDH eqipment or DWDM.

If your alien wavelength is having some different format than SDH/SONET then as far as my knowledge goes you can have a wavlength converter which can change to a wavelength which you are not using and in this converter your signal will be as it is i think. I will check if there is any commercially available.

If the format is SDH/SONET then you can just buy any transponder which can give you a wavelngth which you are not using on your 15454.

juan.rivera@gd-... Fri, 04/24/2009 - 10:44

I should clarify. I am a potential customer looking for a provider that can handle our unique signals. We have an optical transmitter that can be configured on an ITU grid channel but we had initially designed our system to use dark fiber. Now we are attempting to find a way to coexist with a lit network that has Cisco processing equipment in the path.

We operate a large satellite receiving dish antenna that can be tuned to the normal commercial satellite down-link frequencies of 4 GHz or 18 GHz. A typical satellite is similar to a fiber, with many signals frequency division multiplexed onto a transponder that is normally 40 MHz wide. There are typically 24 transponders on a satellite, all separated in frequency. We have a very wideband optical transmitter that is flat from 10 MHz to 18 GHz so we can simply take the output of the antenna, containing hundreds of signals of various types on multiple transponders, and simply feed the whole complex spectrum directly into the optical transmitter's modulator. There is no signal processing involved at all. The result will be a blob of modulated light on an ITU grid channel with energy cenered around 4 or 18 GHz on either side of the optical center frequency, and it won't resemble anything that an optical signal processor will recognize.

viyuan700 Fri, 04/24/2009 - 11:35

If your equipment have to coexist with lit network that has cisco processing equipment then your wavelength should be 50GHz apart and cannot overlap means if your system will provide wavelength at ITU grid cisco DWDM box cannot use the same.

If you are developing best thing will be to provide Optical Transmitter at any ITU grid wavelngth also should have the same wavelngth spacing (i.e 50GHz i think 0.4nm). So that your system can be adjusted to any situation if wavelngth are in use.

As stated in your earlier message you can demux and again mux the wavelngth already there but you have to change them to different wavelngths when they enter again.

If it is possible for you to throw a light on what wavelngth your sytem use and what is spacing maybe will try to see if any solution is possible with 15454.

Tom Randstrom Fri, 04/24/2009 - 11:51

The application you describe is very similar to the what Cable TV signals (43 to 1,000 MHz) are transported from the headend to the nodes. These products (such as Cisco's LaserLink product line) have ITU DWDM interfaces spaced at 200GHz; however, I am unsure what the stability of these lasers are and whether they could operate on a 100GHz channel plan.

This would be a unique implementation for a 15454 network. There definitely isn't a 15454 transponder card for this application. Your signal would have to be inserted directly into the fiber mux (if possible). Plenty of design rules would apply (Cisco Transport Planner), so your service provider's engineering team (with Cisco's team) would need to determine how or if they want to add this service to the existing network. They may just want to use another set of dark fibers for your signals.

Good luck. Let us know the final network outcome!


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