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Directv Over Fiber


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33 replies to this topic

#26 OFFLINE   DSOUND

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Posted 16 March 2014 - 11:04 AM

Problem has been fixed.  The input to the fiber transmitters had 18v coming out of the input.  Some dc blockers and all was fixed.



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#27 OFFLINE   slice1900

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Posted 16 March 2014 - 12:57 PM

Glad you managed to get it fixed. But I'm curious, what do you have as input to the fiber transmitters that is providing 18v?

 

You should only have voltage flowing towards the dish, either coming from a multiswitch or polarity locker. In order to have your fiber transmitter input seeing 18v you must have voltage flowing away from the dish coming from whatever was feeding that transmitter. I would have to guess you're using dual passing splitters, and thus the voltage was coming up the non-fiber leg and down the fiber leg and causing problems. A single port passing or a diode steered splitter would have avoided the issue.


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#28 OFFLINE   HoTat2

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Posted 17 March 2014 - 09:29 AM

Glad you managed to get it fixed. But I'm curious, what do you have as input to the fiber transmitters that is providing 18v?

 

You should only have voltage flowing towards the dish, either coming from a multiswitch or polarity locker. In order to have your fiber transmitter input seeing 18v you must have voltage flowing away from the dish coming from whatever was feeding that transmitter. I would have to guess you're using dual passing splitters, and thus the voltage was coming up the non-fiber leg and down the fiber leg and causing problems. A single port passing or a diode steered splitter would have avoided the issue.

After further study since this thread was started last year;

 

It appears that, at least from all manufacturers of this equipment I've studied since,  the satellite dish (or "trunkside") inputs of a DBS fiber TX module is capable of generating 13v/18v or 13v/18v+22 KHz DC/tone control signals for an LNBF.

 

And I find that while these control voltages are switchable to select between one of the 4 standard types, there is no provision mentioned about the ability to turn the DC/tone signals off altogether.

 

Perhaps for some reason the TS needed to eliminate this voltage *from* one or more of the fiber input TX modules, and therefore needed DC blockers to do it.

 

Just a guess on this later point ... :)   


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#29 OFFLINE   captkillao

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Posted 17 April 2014 - 12:21 AM

Has anyone ran Directv over fiber?  The plan is to have a dish with 4 x 2.3Ghz splitters connected to a local SWM 16.  The 2nd output of the splitters go to fiber TX/Rx.  From there, it goes to another SWM16 to the SWM splitters to receivers.  Thoughts?

 

It will be fine but do not use the splitters. Use a Polarity Locker, Amp, and coupler. That is the proper way to do it. I have used coax over fiber Tx/Rx to do the same over 2000 ft away. Worked out perfectly with no issues so far, about 2 years ago. Good Luck


Edited by captkillao, 17 April 2014 - 12:22 AM.


#30 OFFLINE   dillonjerry

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Posted 15 July 2015 - 10:54 AM

Extending satellite TV over fiber can be done in a few different ways.  I have designed many of these systems, and there are only a few companies that can make the equipment able to do this.  Technically, there are two main approaches:

Most Common:  The main approach for this problem has traditionally been to send the LNB downlink frequencies from the dish to the multiswitch over fiber.  The main reason being that RF over fiber (usually) only works in one direction.  You have a laser on one end and a photodiode on the other.  There is no way for a signal generated at the receiver location to be sent back to the transmitter site.  This means any RF communication only goes in one direction.  In satellite TV systems, the IRDs need to be able to communicate back to the multiswitch, so traditionally fiber links have not been available for this link.  Several companies have been mentioned to provide the LNB downlink solution (foxcom, dawnco, ect) and they all have their pros and cons.  The main problem most of these solutions have is that they either don't provide polarity locking, or they are not weather proof (usually both).  There is another company, Optical Zonu, that manufactures wideband RF over fiber transmitters in outdoor IP-67 rated enclosures.  Every connector is waterproof and they run on DC power; very practical systems.  The ability to install the optical transmitters right next to the dish makes installation way easier.

New Approach:  Optical Zonu now manufactures a multiswitch fiber extender compatible with the DirecTV SWM system.  They are the only company in the world that has this solution.  When you are extending service for 8 tuners or less, such as in an outbuilding or guest house this solution makes the most sense.  The SWM fiber extender uses two sets of optics transmitting in both directions over the same fiber to carry the return path from the IRD back the multiswitch.  This solution is more economical because it only requires two optical transmitters instead of the 4-6 required by an LNB downlink system.  The limiting factor being that the number of tuners supported is limited to the output capacity of the multiswitch (typically 8).  However for most fiber extender applications the SWM fiber extender is the best solution.  

 

Either solution is going to be more expensive than installing an additional dish antenna.  However for installations where this is not an option, fiber solutions are available.  Its best to contact a company that sells or manufactures this equipment, as they are best qualified to design these types of systems.



#31 OFFLINE   dillonjerry

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Posted 15 July 2015 - 11:14 AM

I found information on the SWM over fiber extender system on the following page: http://www.opticalzo...swm-fiber-link/



#32 OFFLINE   jlmtech

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Posted 15 July 2015 - 02:31 PM

Interesting discussion.I think you covered all the pros and cons of the fiber, indoor/outdoor, power insertion/polarity locking, etc. The first is well defined as you note. At the end, you can always get an IPxx box to enclose, power inserter, CWDM for single fiber and so on.The issue is,  as always, cost. The driving factor, or lack thereof, has always been volume commitment to get cost down to an acceptable level through the chain. Global Invacom even has an integrated LNB with fiber output that they market primarily in Europe. Not sure what the volumes are. Its made to drive a set of multi switches with integrated fiber RX. Was tried here in the US but never caught on.

 

Th SWM extender has been bantered around for years. Again, cost is key on the unit. In volume, you probably have a BoM cost of 30-40 USD at high volume. At lower volumes, can you compete with the delivered cost of a SWM. Consider also that the main cost is running the fiber to the outpost, 1, 6, 12 is not much different and substantially more than the equipment. So why not use the former solution added on as another "node". You will also have fiber for other services as well like Active Ethernet and the like. 



#33 OFFLINE   dillonjerry

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Posted 17 July 2015 - 03:14 PM

I have seen those fiber LNBs before, another great idea that never caught on.  The SWM extender will always be an expensive solution, its really just for the 1% or less of installations that really really need it.  It provides a solution for an impossible to solve problem for a client that is willing to pay for the impossible.  I agree that often it is a better approach to use LNB transmitters and just add another SWM node, but Ethernet can be added with a SWM extender just as easily.  The real added value of using the SWM over fiber system is that you get Whole Home support for Genie DVRs, something you could never get by adding another SWM node.  



#34 OFFLINE   slice1900

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Posted 17 July 2015 - 04:43 PM

Why is this starting to sound like a marketing spiel?


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