Author Topic: RF OVER FIBER - what are your experiences?  (Read 1427 times)

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Offline PETER ERSKINE

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RF OVER FIBER - what are your experiences?
« on: March 28, 2019, 01:15:48 am »
I use a couple of devices to carry broadband RF over fiber.  An inexpensive one from RFVENUE for about 3K and a multi channel one from WISYCOM for 20k. 

Typically I am trying to get UHF and VHF reception from far away (>300' and <2000')

What other devices are there?  I am not particularly interested in component level parts, just off the shelf devices.

This is a pix of the RFVENUE device:
 

Offline coppercone2

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Re: RF OVER FIBER - what are your experiences?
« Reply #1 on: March 28, 2019, 02:04:29 am »
Is this for commercial use?

For home use, at those prices, would it not be more cost effective to demodulate the signal at the antenna and transmit the lower frequency demodulated stuff?

How much do these things go for second hand? What is the life time of the optical section?

Compared to a LME400 for 1000 feet thats going to be ~20dB loss. Did you look at various coax options to see if there is a acceptable cheap solution?

https://www.timesmicrowave.com/calculator/?Product=LMR-600&RunLength=1000&Frequency=500

1000$/dB seems like alot. How does SNR compare from a LNA to regain loss vs the Optical solution? I think you need to evaluate the benefit vs your exact wiring run size to see how much better your signal quality will be to compare with amplification losses with good coaxial cable.

« Last Edit: March 28, 2019, 02:17:38 am by coppercone2 »
 

Offline TheUnnamedNewbie

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Re: RF OVER FIBER - what are your experiences?
« Reply #2 on: March 28, 2019, 09:23:21 am »
Is this for commercial use?

For home use, at those prices, would it not be more cost effective to demodulate the signal at the antenna and transmit the lower frequency demodulated stuff?


Depends on what you are doing - if you have line-of-sight, it might be easier still to up-convert to higher carrier and use high-gain antennas to get a point-to-point link.

These RF-over-fiber solutions are also gaining interest in 5G, where you could do complex modulation processing at the bottom of the tower, and then only have an optical-to-RF converter and an amplifier near the antenna. Also for larger scale solutions, like a single point in the block where all the RF processing is done, and then fiber distributes it all around the city block to nano-cells.

I don't have any details as I work on different solutions, but as these are 'competitors' to what I do for a living I would be interested in any information shared here. Generally these optical solutions all suffer from the same drawback: doing coherent optical requires high cost components, and optical fiber is a pain to run and terminate, and expensive. They are also very sensitive - bit of dust or condensation or air-gap and your SNR is just gone. We are talking about a few micrometers or less in alignment error.
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Offline Lord of nothing

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Re: RF OVER FIBER - what are your experiences?
« Reply #3 on: March 28, 2019, 10:19:23 am »
 :palm: I hat a the same Problem but with different Signals.
1) Sat. I choose an SAT -> IP Device from a German Company (who have me Discount for trial  :popcorn:). Behind that Box I put an Fiber Media Converter.  >:D
2) For SDR Stuff I got this: https://www.icronshop.com/fibre-usb-extenders/icron-raven-3124
Mine hat some bad solder joint I guess (when the Temp drop under 10c the lost the connection between each other). The Works perfect with the "narrow" SDR with 2Mhz Bandwith. A HackRF need sadly enough to much band with.  :=\
Made in Japan, destroyed in Sulz im Wienerwald.
 

Offline Yansi

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Re: RF OVER FIBER - what are your experiences?
« Reply #4 on: March 28, 2019, 10:36:24 am »
2) For SDR Stuff I got this: https://www.icronshop.com/fibre-usb-extenders/icron-raven-3124
Mine hat some bad solder joint I guess (when the Temp drop under 10c the lost the connection between each other). The Works perfect with the "narrow" SDR with 2Mhz Bandwith. A HackRF need sadly enough to much band with:=\

Strongly doubt it, the converter thingy would have to be very very slow otherwise. They claim even USB 3.1, I doubt hackRF even uses one (likely just USB 2.0 in HS mode - nowhere close to 3.1 speeds). The problem may be elsewhere.

//EDIT: Confirmed, HackRF uses Hi-Speed USB 2.0.
« Last Edit: March 28, 2019, 10:38:14 am by Yansi »
 

Offline Lord of nothing

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Re: RF OVER FIBER - what are your experiences?
« Reply #5 on: March 28, 2019, 10:46:43 am »
 ;D quite all of my Pc are to slow for the HackRF just my i7 Thinkpad work without any problem.  ::) I had to send it back because the make trouble when the Temp was falling.
The company dont know what happened so I had to send it to Canada (bought from UK  :palm:) and the will check it.
Made in Japan, destroyed in Sulz im Wienerwald.
 

Offline coppercone2

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Re: RF OVER FIBER - what are your experiences?
« Reply #6 on: March 28, 2019, 08:34:18 pm »
Is this for commercial use?

For home use, at those prices, would it not be more cost effective to demodulate the signal at the antenna and transmit the lower frequency demodulated stuff?


Depends on what you are doing - if you have line-of-sight, it might be easier still to up-convert to higher carrier and use high-gain antennas to get a point-to-point link.

These RF-over-fiber solutions are also gaining interest in 5G, where you could do complex modulation processing at the bottom of the tower, and then only have an optical-to-RF converter and an amplifier near the antenna. Also for larger scale solutions, like a single point in the block where all the RF processing is done, and then fiber distributes it all around the city block to nano-cells.

I don't have any details as I work on different solutions, but as these are 'competitors' to what I do for a living I would be interested in any information shared here. Generally these optical solutions all suffer from the same drawback: doing coherent optical requires high cost components, and optical fiber is a pain to run and terminate, and expensive. They are also very sensitive - bit of dust or condensation or air-gap and your SNR is just gone. We are talking about a few micrometers or less in alignment error.

That is a good idea so long you accomodate a rain fade budget
 

Offline hagster

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Re: RF OVER FIBER - what are your experiences?
« Reply #7 on: March 28, 2019, 11:14:05 pm »
It might be worth getting prices from ViaLite also.

If it matters for your application, make sure you look into the linearity and dynamic range of the various systems.
 

Offline PETER ERSKINE

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Re: RF OVER FIBER - what are your experiences?
« Reply #8 on: March 29, 2019, 03:43:10 am »
These are for professional use.  Typically the cable route is hard or the distance is long which precluded LMR400.  A lot of times the house has fiber but no RF installed.  I use it on the Macy's Parade for wireless mics.  Th RX is located at the FOH position near the performing area on 34th street.  However the mics must work around the corner on 6th ave as the floats approach and the only way to connect is via fiber provided by Verizon under the streets.

On another show we had a 10 watt 460MHZ band repeater and 5000' away the TX could still be heard but radios couldn't hit the repeater so we put second antenna there on RFOF.
 

Online ogden

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Re: RF OVER FIBER - what are your experiences?
« Reply #9 on: March 29, 2019, 01:16:36 pm »
These are for professional use.  Typically the cable route is hard or the distance is long which precluded LMR400.  A lot of times the house has fiber but no RF installed.  I use it on the Macy's Parade for wireless mics.  Th RX is located at the FOH position near the performing area on 34th street.  However the mics must work around the corner on 6th ave as the floats approach and the only way to connect is via fiber provided by Verizon under the streets.

What if you put receivers next to antenna and run audio over IP? I think IP circuits may be less expensive than dark fiber and IP solution may pay off quickly, not to mention that it is way more flexible.
 

Offline dmills

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Re: RF OVER FIBER - what are your experiences?
« Reply #10 on: March 29, 2019, 03:20:35 pm »
Low latency AOIP works just fine AS LONG AS YOU CONTROL THE NETWORK!

Basically AES67/2110-30 (Same thing pretty much) needs reliable UDP delivery over a multicast aware network, with defined maximum amounts of buffering. If you have that it does just fine (Well providing the switches are PTP aware or sufficiently low latency), but trying it over a public packet switched network?
Problematic at the latencies I would want for a live show.

Give me a pile of Arista 7150s and fibre and I can cart almost unlimited amounts of audio around and it will all be in sync, with latencies in the few ms region (And the SAME latency to all end points), but I would not try that over the public network. 

Dante is NOT better in this regard.

Of course if you don't need low latency then the game changes.

Regards, Dan.
 

Online ogden

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Re: RF OVER FIBER - what are your experiences?
« Reply #11 on: March 29, 2019, 06:48:53 pm »
Give me a pile of Arista 7150s and fibre and I can cart almost unlimited amounts of audio around and it will all be in sync, with latencies in the few ms region (And the SAME latency to all end points), but I would not try that over the public network. 

Arista for voip? LOL. I'm afraid that while typing your internet search query, you confused stock exchange with TV/radio studio. When you want to replace dark fiber with Ethernet/IP circuit you obviously don't use public network :palm: - you look for carrier grade Metro Ethernet. Obviously you shall look for company which can not only offer strict SLA, but deliver it as well. There are loads of Carrier Grade Ethernet providers in Manhattan area.
 

Offline coppercone2

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Re: RF OVER FIBER - what are your experiences?
« Reply #12 on: March 30, 2019, 02:08:52 am »
the only thing, i wonder if someone would try to troll a wifi network during a parade with a DOS

I would want wired.
 

Offline dmills

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Re: RF OVER FIBER - what are your experiences?
« Reply #13 on: March 30, 2019, 12:27:21 pm »
Arista for voip? LOL. I'm afraid that while typing your internet search query, you confused stock exchange with TV/radio studio.
No internet searches necessary, there is a 7124 in my broadcast toys rack, with a Embrionix Encap to get from SDI to IP (2110 or 2022-6) and some IP capable kit from work.

My day job is designing equipment for TV studios and trucks, and yes modern TV production will absolutely use the 7150s and there more modern brethren from Arista, Melanox or Cisco. A single 4k60 ST2110 essence is over 10Gb/s even a mundane 1080P60 feed is ~3Gb/s.

This is not compressed domain stuff, but compressed domain is a pain in the arse in a production context where you  may be wanting to key off croma or suchlike. In the live production game the cost of even a very quick switch is small compared to the costs of a old school SDI switcher once you get above a few hundred sources or dests, and that trasistion point is getting smaller fast.

The new BBC Wales facility for example is an IP infrastructure built as a leaf and spine network on 100Gb links, and IIRC NEPs OBZ is a Grass Valley/Cisco infrastructure in a truck.

For audio only (as opposed to audio tightly synced with video), Dante or Ravenna (Basically AES67) over the MAN might be ok, but that is a high stakes game on a big event. 

Yep, the switch companies developed a lot of this stuff for the HFT crowd, but you better believe broadcast is not afraid to leverage the tech, our needs are close enough (Actually the early low latency switches for HFT borrowed experience from the broadcast SDI switcher game where precisely timed near zero latency switching was a hard requirement).

Regards, Dan.
 

Offline PETER ERSKINE

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Re: RF OVER FIBER - what are your experiences?
« Reply #14 on: March 30, 2019, 06:24:23 pm »
What if you put receivers next to antenna and run audio over IP? I think IP circuits may be less expensive than dark fiber and IP solution may pay off quickly, not to mention that it is way more flexible.

Typically RFOF is used for additional antennas.  For instance for the New Years celebration in Times square, wireless Mics and IFB are required to work from 42nd street up to 48th street and to the top of the Ball tower.   Every block has local RX antennas both for Wireless mics and Intercom (Clear-Com Freespeak)  All of these are run with fiber.
 

Offline dmills

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Re: RF OVER FIBER - what are your experiences?
« Reply #15 on: March 30, 2019, 06:42:37 pm »
That is a NASTY RF environment as well, probably why so many rx aerials are needed. Production audio usually lives in between TV channels, and NY is not short of high powered transmitters.

The usual trap with RF over fibre (Really over anything except copper) is the dynamic range which is generally smaller then that of a really good receiver because the RF->Fibre box usually lacks the kind of filtering that a good cavity or stub preselector can buy you.

It is a solution to a specific problem, but is not really generally applicable outside of that specific problem space.

Regards, Dan.
 

Offline PETER ERSKINE

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Re: RF OVER FIBER - what are your experiences?
« Reply #16 on: March 31, 2019, 01:02:18 am »
That is a NASTY RF environment as well, probably why so many rx aerials are needed. Production audio usually lives in between TV channels, and NY is not short of high powered transmitters.

The usual trap with RF over fibre (Really over anything except copper) is the dynamic range which is generally smaller then that of a really good receiver because the RF->Fibre box usually lacks the kind of filtering that a good cavity or stub preselector can buy you.

It is a solution to a specific problem, but is not really generally applicable outside of that specific problem space.

Regards, Dan.

The wisycom system has fully programmable HP, LP, Notch filters on each input.  Their actual dynamic range is much more than most wireless Rx.
The system has 2 channel in each direction which allows for IFB TX as well.  Their MPA221 power amp has clever multi amp Parallel/series configuration which eliminates any Intermod creation when amplifying the broadband Max 0 dBM fiber signal 

The RFVENUE system has no built in filtering and has higher noise floor but for RX of dozens of channels it is fine.  RFVENUE does not do TX.

I am interested in any other systems which are out there

« Last Edit: April 01, 2019, 02:44:48 am by PETER ERSKINE »
 


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