Jump to content

Video Distribution for Multiple Monitors within the field of an induction loop.


Recommended Posts

I am looking at a video installation for a church, probably to 2 pairs of monitors at the front of the church (Distance approx 30M) and one at the rear of the church (10M) so 2 or maybe 3 separate feeds with local distribution/splitting as necessary. I have not been actively involved in video for a few years now. The last event I worked on, I seem to remember using a system utilising coax cable of some sort to adapter boxes (to HDMI)  by each monitor. What system might that have been? 

What other systems are there now? 

I should mention that the whole of the system will be within the field of an audio frequency induction loop system so the signal and cables needs to stand a very good chance of being immune to magnetic interference.  The main run(s) to the front can be accomplished in the under floor heating duct down the central aisle, so some distance from the AFILS cable as will the monitors be. The comfort monitor at the rear, if placed in the ideal position will be extremely close to the loop cables which is doubled at that point so some experimentation as to position will be needed there. 

T.I.A. 

Bazz

 

 

 

Link to comment
Share on other sites

I've not noticed issues between AFILS and SDI, but if you were really concerned I'd look at a HDMI over CAT5/6/7 system, as the twisted pair nature of the cabling should make it pretty resistent to magnetic radiation.

I'd probably be looking at HDBaseT. Many HDMI CAT5/6/7 systems do distribution to multiple screens which might be cleaner than a whole pile of SDI converters and distribution. The cabling is also cheaper and termination is more accessible (a good BNC crimp tool is £100+, vs CAT5/6 termination kit which can be found very cheaply).

Link to comment
Share on other sites

What J Pearce says.
At 30m (even if cable route ends up longer), you are well within range for even the "Lite" variant of HDbaseT (70m), which is more common at the budget end of the market. Note that the really cheap end HDMI-over-CATx kits are usually not to any standard at all, and some need two length-matched cables (there have been several HDbaseT threads on here before). Because HDBaseT is a standard, you can mix and match vendors at the ends if you need to. Some of the pro-market receivers have two HDMI outputs from a single receiver which might be what you are looking for to feed pairs of screens? Remember the reliable length of the HDMI cable is only about 5m, so they would have to be close together.

If cost is an issue, second hand sets of kit from Kramer et. al. are now showing up in the usual sorts of places because the standard has been around for long enough.

Link to comment
Share on other sites

1 hour ago, Bazz339 said:

Anyone used these Pro Signal units ?

Yes, however the 70m tag is a little hopeful, there are several versions, I think 4, in the range and it's worth getting a 'size' bigger than expected.

For cat5 expect 1/3 and cat5E 1/2 of that didstance.

Link to comment
Share on other sites

Posted (edited)
2 hours ago, sunray said:

Yes, however the 70m tag is a little hopeful, there are several versions, I think 4, in the range and it's worth getting a 'size' bigger than expected.

For cat5 expect 1/3 and cat5E 1/2 of that didstance.

Longest run is 30m. When you refer to Cat 5 or 5E are you referring to grade of cable? I am happy to use Cat 6 or 7 cable if that will make a difference if the price difference isn't too much. 

Edited by Bazz339
Link to comment
Share on other sites

1 hour ago, Bazz339 said:

Longest run is 30m. When you refer to Cat 5 or 5E are you referring to grade of cable? I am happy to use Cat 6 or 7 cable if that will make a difference if the price difference isn't too much. 

Yes, the type of cable.

Off the top of my head I think it says something like 70m for cat6 or 7 and 50m of cat5E, I don't think cat5 is quoted for use.

Very first ime I used it the instructions weren't available to me, 2x 18m cat5 leads with a f/f coupler gave an unacceptable signal. Using the larger unit (IIRC 100m) was fine.

A little experimentation later on we established 70m of cat6 was the limit, for the 70m version, but not if it included any joints (like via a patchbay & sockets). However cat5E didn't work as well as the stated length and realistically the limit in terms of the 70m marking is about 1/2 or 35m and for cat5 about 1/3 of the 70m or 25m. All of the figures are approximate and deliberately remembered as a fraction of the 70m. Please bear in mind that adding joins has immediate effect. The 100m version works with 100m of cat6 but the lesser cables actually works better than those fractions although it's how we treat them.

 

I'd go for the best cable to ensure the best chance.

Edited by sunray
Running lower resolution does allow longer runs
Link to comment
Share on other sites

I've got a bundle of the blackmagic convertors. They're good, but get rather warm in use so need ventilation, and I've had a few die - I think due to earth loop currents across circuits.

Depends what BNC crimp tool/die you have as to whether you will need another, they're generally specific to the cable/connector combination.

Link to comment
Share on other sites

Another option would be optical HDMI cables. 

 

Should be immune to loop interference, no crimping required and relatively straightforward to install with no converter boxes etc. 

Potential downsides are that the ends are relatively large so harder to run behind walls or under floors. And they can be fragile - be careful with tight corners etc. 

  • Upvote 1
Link to comment
Share on other sites

  • 4 weeks later...
On 7/7/2022 at 11:37 AM, Stuart91 said:

Another option would be optical HDMI cables. 

 

Should be immune to loop interference, no crimping required and relatively straightforward to install with no converter boxes etc. 

Potential downsides are that the ends are relatively large so harder to run behind walls or under floors. And they can be fragile - be careful with tight corners etc. 

I do a lot of this type of work in lecture theatres. HDBaseT is cheapest - I'd recommend shielded Cat cable as a minimum. We use the Extron DTP system mostly with their cable and connectors but your budget may not go that far?

We've tried optical fibre cables from Extron and Kramer. Mostly good things about the Extron if over 15m (a lot of failures on the 15m and 10m versions) and lots of failures on the Kramer (their plenum series with the mini HDMI connectors to run easily and then use a plug-on adapter - they're a nightmare).

SDI is ok but if budget isn't an issue I'd go AVoIP for future proofing. Expensive converters (costs are coming down slowly though) but cabling is cheap as you like and any future expansion is as easy as adding another receiver on the network - make the tie - job done.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...