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BNC RF & SDI Mulitcore


Constantin
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In an effort to remove myself further away from the set I have been looking into various options. 

Converting to a Dante setup would be the longterm goal, but for the moment that's too expensive, as I would need a new recorder at least and other gear. 

RF-over-fibre would be another option, but that, too, is quite expesive. 

 

So I thought simply going with long BNC cables to remote the antennas would be the easiest option. This would be even easier with one cable that carries both signals and then of ocurse I thought I should combine this with the video signals as well. Maybe put my video receiver at the set side of the cable to go wireless from video village and then send it down the 50m cable to my cart. Does anyone have experience with such a setup? I am particularly interested in any interference from the sdi signals to the rf? 

 

Thanks!

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I don’t have any experience in carrying RF and SDI in the same multi-core, but definitely, the impédances are different. 75 Ohm for video vs 50 for RF. 
Also, above 10 meters, you’ll need quite serious RF cable if you don’t want too much loss.

I have some of these simple RF cables and they are not  flexible at all.
I am afraid you won’t find any multi cable with such qualities.  
Fiber is definitely the best option if you want to keep an eye on your receivers.
I don’t know the price range, but BS-RF in France have smart solutions, certainly less expensive than Wisycom solutions. https://www.bs-rf.com/en/products/fiber-optic-rf-offset/

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2 hours ago, henrimic said:

I don’t have any experience in carrying RF and SDI in the same multi-core, but definitely, the impédances are different. 75 Ohm for video vs 50 for RF. 
Also, above 10 meters, you’ll need quite serious RF cable if you don’t want too much loss.


Yes, I know the impedances are different, but that’s not necessarily a reason for interference, but certainly possible. I would have thought that standard RG58 would be good enough. It has a loss of about 1dB per every 3m, so I can make up for that with my Betso antennas. The Wisycom RF-o-F is very expensive as is that of RFVenue, although the latter especially looks like a great system. But thanks for the tip regarding BS-RF (Hopefully that‘s not the short form for that other BS term), that looks like a great system and I really like the fact that they have a two-channel box and a duplex box. 
 

thanks!

 

6 hours ago, DanieldH said:

Maybe the hotline at sommercable.com has an opinion on that and eventually a product.

 

Good idea, I‘ll give them a call

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I experimented with some snakes made from Canare multi conductor coaxial (v-4cfb I think). For multi camera video feeds.   No 50ohm lines but I found it was a bit too heavy and awkward to use efficiently on set. 
 

One cable is a nice idea but make sure you try before you buy. 

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9 hours ago, Constantin said:


Yes, I know the impedances are different, but that’s not necessarily a reason for interference, but certainly possible. I would have thought that standard RG58 would be good enough. It has a loss of about 1dB per every 3m, so I can make up for that with my Betso antennas. The Wisycom RF-o-F is very expensive as is that of RFVenue, although the latter especially looks like a great system. But thanks for the tip regarding BS-RF (Hopefully that‘s not the short form for that other BS term), that looks like a great system and I really like the fact that they have a two-channel box and a duplex box. 
 

 

No.  Standard RG58 will NOT be adequate, especially for a 50m run!  Even the heavy stuff that's about as big a round as a garden hose would be questionable at that distance.  Unless you can somehow digitize it all and then "decode it at your end (I've never heard of that being done) you're not going to be able to send an RF signal work and have it "well" at that sort of distance.  

 

Tom

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5 hours ago, TomBoisseau said:

Unless you can somehow digitize it all and then "decode it at your end (I've never heard of that being done) you're not going to be able to send an RF signal work and have it "well" at that sort of distance

RoF (radio over fiber) is an "analogue" solution and works over kilometres.

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2 hours ago, Vincent R. said:

RoF (radio over fiber) is an "analogue" solution and works over kilometres.


Yes, it’s a great system. It has a signal loss of 0,5dB per kilometer! But it’s also very expensive. The RF Venue and I think also the Wisycom systems are in the $6000 range for a dual channel rig. That’s too much for me at the moment for this kind of tech. 
I have enquired with BSRF about their pricing, but it’s likely in a similar price range...

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2 minutes ago, DanieldH said:

Not sure, if this could work or not. 

Made for a completely different application and signals but a relevant spectrum and lower price range:

https://thorbroadcast.com/products/cable-tv-catv-rf-45-900mhz

I wonder, if these fibreoptic cables are durable enough for non permanent installations.

Interesting find! A quick look at the specs it says 75 ohms, but people using that for our systems with good results anyways; See this article for example;
https://wavreport.com/2017/08/04/tutorial-diy-microphone-antenna-distro/

And specifically Jacob Varley's setup @ 75 ohms. 
 

 

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12 minutes ago, DanieldH said:

 

50 vs 75ohm:

 

 

Yeah so combine that knowledge with the fact that your antennae will be closer anyways with the "cheaper" RF over fiber brand you linked above, and real world loss might be negligible.

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7 hours ago, Vincent R. said:

Yeah so combine that knowledge with the fact that your antennae will be closer anyways with the "cheaper" RF over fiber brand you linked above, and real world loss might be negligible.

Worth a try, if thor or even a European competitor provides test equipment. Not my project though.

 

EDIT:

There is even much cheaper stuff from china: http://www.hy-fiber.com/product/CATV-Solution----

Prices are on aliexpress.

 

That all means, dealing with a rack sized unit with a fan on the remote end of the system.

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I feel left out... (Or, I fail to see the problem...)
50 meters of SDI is no problem. SDI cable is like, 1 euro a meter?

SDI can carry 8 channels of 24 bits sound.

Cat 5 (or, go crazy, Cat 6) should do the trick as well.
So, what is the problem of getting some SDI embedders / de-embedders? The whole setup should be some 500 euros per 8 channels...
(Unless BlackMagic stuff ain't good enough.)
Then if there is video assist / cams, they have SDI embedders as well... (A cam is one too, same as my Pix recorder.)

5 hours ago, DanieldH said:

I wonder, if these fibreoptic cables are durable enough for non permanent installations.

 

Fibre is normally packed in a Kevlar shielding. At a festival I've worked we had a big forklift driving into our fibre cable, taking down lots of fences and nearly tore down a tent. The cable survived.

(Glass is a liquid, thus quite flexible / stretchable. Kevlar does not stretch at all. I would not worry about that.)

 

So, what am I missing here?

 

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2 hours ago, Bouke said:

So, what am I missing here?

One might wish to have the RX units close by, to have an eye on RF-, audio signal, battery level. (Even though this information might also fit in an audio channel or AES channel, such a system is currently not yet known to me.)

 

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55 minutes ago, DanieldH said:

One might wish to have the RX units close by, to have an eye on RF-, audio signal, battery level. (Even though this information might also fit in an audio channel or AES channel, such a system is currently not yet known to me.)

 

 

Ok, fair enough (I'm an IT tech / editor, this is not my line of work. I'm a hacker / developer who makes the impossible not so impossible).
Of course the metadata mentioned could fit into the stream, but one would need to get it out of.
Monkey patching would be to put a cheap webcam on the devices, (If they display all status at once, and if so, that

would set you back another 100 bucks.)

 

 


 

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37 minutes ago, Bouke said:

 

Ok, fair enough (I'm an IT tech / editor, this is not my line of work. I'm a hacker / developer who makes the impossible not so impossible).
Of course the metadata mentioned could fit into the stream, but one would need to get it out of.
Monkey patching would be to put a cheap webcam on the devices, (If they display all status at once, and if so, that

would set you back another 100 bucks.)


That‘s a pretty cool idea, actually. I like these kinds of out of the box approaches. I have 13 channels of audio going one way, and four going the other. That might be doable, but for me the biggest issue is that I would have to cut my cart in half and put one half near the set and one half next to me. Certainly possible, but for the time being not my favourite approach. 
 

 

9 hours ago, Vincent R. said:

Interesting find! A quick look at the specs it says 75 ohms, but people using that for our systems with good results anyways; See this article for example;
https://wavreport.com/2017/08/04/tutorial-diy-microphone-antenna-distro/

And specifically Jacob Varley's setup @ 75 ohms. 
 

 


Thanks for those, that’s pretty interesting. Not sure why that didn’t occur to me, as I had read about that before, but it didn’t. Anyway, I have about a dozen 75 ohm bnc cable drums of lengths between 50 and 150m at home, so I will just try that out. That would certainly be the cheapest option, but I‘m not keen on lugging two cable drums around, plus possibly another two for the video feed. 
 

9 hours ago, DanieldH said:

Not sure, if this could work or not. 

Made for a completely different application and signals but a relevant spectrum and lower price range:

https://thorbroadcast.com/products/cable-tv-catv-rf-45-900mhz

I wonder, if these fibreoptic cables are durable enough for non permanent installations.

 

Thanks, that’s a very cool find! That’s certainly a good option to look into, although that still comes to a total of about $2k. But more approachable than 6k. 
Still, I think I‘ll pursue the one big cable way first and see where that takes. 
So I take none of you has tried that?

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5 minutes ago, Constantin said:

That‘s a pretty cool idea, actually. I like these kinds of out of the box approaches. I have 13 channels of audio going one way, and four going the other. That might be doable, but for me the biggest issue is that I would have to cut my cart in half and put one half near the set and one half next to me. Certainly possible, but for the time being not my favourite approach. 

And I think you have to give up control then as well. My take is there are about 2 options for controlled "remote RF"; or a long cable for the antennae (fiber or coax), or some Audio over IP route (RX box on set). 

@Jan McL is/was kinda the pioneer here on the forum regarding CAT5/6 audio btw. But again, you loose the control.

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7 minutes ago, Bouke said:

 

Ok, fair enough (I'm an IT tech / editor, this is not my line of work. I'm a hacker / developer who makes the impossible not so impossible).
Of course the metadata mentioned could fit into the stream, but one would need to get it out of.
Monkey patching would be to put a cheap webcam on the devices, (If they display all status at once, and if so, that

would set you back another 100 bucks.)

 

 


 

Your idea was cool and intuitive, in theory. But besides the UI issues, what you would to is, to put the most important signals in your sovereignty onto a signal of lesser importance that is governed by another department (the camera dept). They may reboot their camera or some element in the video distribution system is powerered off for some routine reason in the very moment when you want to check that your lav mics don't rustle, or worse, during take.

These RX user interfaces are duplex, LCD to user and button pushes to the unit. There are not many systems out there that are not rack sized and provide RX remotability. The rack equipment that exists is mainly build for stages (music, theatre, sports, etc). The only system I know of not in 19' form factor that provides this feature is the Aaton Hydra. However this may change now as the new Wisycom MPR54 brings USB-C and bluetooth support to monitor and control the RX.

 

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8 minutes ago, Bouke said:

I'm missing the fun, Elaborate or tell met to shut up.

 

I don't deal with long range antenna stuff myself, but I see this problem for example:

 

Imagine my receivers are on set, then SDI to cart 50m away from set.

Now I have a RF problem and need to switch channels on the receivers.

so I run 50 to the set, swap channels, run 50m back and check audio only to find that it didn't solve the issue.

rinse and repeat : ) 

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10 minutes ago, Constantin said:

Thanks, that’s a very cool find! That’s certainly a good option to look into, although that still comes to a total of about $2k.

2k would be only for one antenna as far as I could see. But check the Chinese source further up in my edit. (all hypothetical, never been known to work)

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