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Author Topic: RF over fiber  (Read 6225 times)

Mac Kerr

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Re: RF over fiber
« Reply #10 on: October 09, 2014, 08:43:02 AM »

Right indeed- certainly not ideal but most shops do not have FC/APC on hand

Indeed, it is a pain for a shop to stock a whole range of fiber just for a single device. Since the system seems to be working fine with the adapters, I wonder why not offer it with regular ST connectors so the shops only have to have MM and SM fiber, and not also FC/APC.

Mac
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Jason Lavoie

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Re: RF over fiber
« Reply #11 on: October 10, 2014, 08:41:12 AM »

Indeed, it is a pain for a shop to stock a whole range of fiber just for a single device. Since the system seems to be working fine with the adapters, I wonder why not offer it with regular ST connectors so the shops only have to have MM and SM fiber, and not also FC/APC.

Mac

The use of single-mode implies that the system is geared for much longer runs than 300'
The connector type will make a difference after some distance.

Jason
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Pete Erskine

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Re: RF over fiber
« Reply #12 on: October 10, 2014, 11:26:47 AM »

Does using adapters not undo the benefit of APC connectors? This seems pretty backwards, since you add 2 more points of reflection into the path, which is what the APC connectors are designed to mitigate

RFoF is an analog conversion of the RF spectrum.  Reflections within the fiber caused by flat polishing creates an effect like intermodulation or could damage the laser.  Just the couple of APC connections in the fiber helps eliminate the reflections by the other Flat polished connections.  The correct way to eliminate the effect is with optical isolators which twist the light 45° which makes the reflection twist another 45° coming back.  Some RFoF have this built in.

Here is a nice intro to RFoF: http://www.rfsolutions.com/fo-rf1.htm

Here is an example of an optical isolator: http://www.agiltron.com/PDFs/1310-1550-single-mode-single-stage-optical-isolator.pdf



« Last Edit: October 10, 2014, 11:34:29 AM by Pete Erskine »
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Pete Erskine
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Scott Holtzman

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Re: RF over fiber
« Reply #13 on: October 11, 2014, 05:56:13 AM »

The optical receiver pretty much directly drives the RF exciter then to a broadband amplifier.  Since the filters have to be wide the chance of also amplifying intermodulation products is high.  We had a ton of problems with the rfof block converts use to extend catv service. 
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Scott AKA "Skyking" Holtzman

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Re: RF over fiber
« Reply #13 on: October 11, 2014, 05:56:13 AM »


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