Long Distance DMX

[Brian]

Looks like I'm going to need to send a universe of DMX wirelessly over a minimum of 2km, ideally I'd like 5km.

 

Unobstructed line of sight is not a problem, transmit power source is not a problem, receive power source will need to be battery. If the receiver is an off-the-shelf product it'll need to be IP68, but only when it's not operating. There's no opportunity for an intermediate repeater.

 

Anyone done anything like this?

[bruce]

oooh interesting - the IP68 (when not operating) and lack of mains power has got my attention!

 

There are several (fairly niche) 2.4GHz and 5GHz wifi bridges on the market which claim IP68, and are good for several km, so I guess that could be used for Artnet?

[Ynot]

Can't help directly but curious as to what you're sending the signal to.... :P

[maeterlinck]

Environment will be a big factor. As will what the receiver is on - truck, house, person, etc.

Off the shelf products might work - Wireless Solutions would be the place to start.

Otherwise, custom with things tweaked to match your needs.

Data rate, universe size, and real time requirements will also be considerations.

Wifi bridge might be a good route as well at the potential cost of latency.

Battery and IP ratings should be easy to solve, depending what the RX goes on.

 

PS: I work for a special projects company so merrily get involved with fun things like this when asked.

[the kid]

I have not, But I am fairly my boss has done using the unifi airmax stuff a few years back - https://help.ui.com/hc/en-us/articles/205197750-airMAX-Which-product-should-I-use-#2 Having a quick look about some people have done battery POE packs, I guess depends on your access to replace said packs.

 

It must be ip rated due to how they are designed to be installed, but cant see right now how much.

 

I am also aware of some tests people have done using their kit for remote control diggers / earth movers using airmax stuff on gyroscopes.

Edited September 2, 2020 by the kid

[Tomo]

We did a similar distance when programming for a rather tall building a few years back.

 

The link was a point-to-point wireless ethernet bridge.

Carried about 30 universes of sACN easily, but struggled with bi-directional traffic.

 

Hard power was available both ends, however I believe the actual unit was 12 or 24VDC powered so easily made battery.

 

Main difficulty was aiming the antenna, both ends needed to be pretty accurately focused for it to work.

 

Does either end need to move?

Edited September 4, 2020 by Tomo

[bruce]

It’s a fascinating project

 

I can understand the wireless bridge being fine with Udp or one directional traffic, but struggling with bidirectional. These things are half duplex, to tune them find a network engineer who learned his trade in the thin-net days.

 

Most of the wireless bridges do have some tuning which allows you to optimise the timing for the link distance

[dbuckley]

When you say "battery", the question becomes one of power budget, how long does it have to operate for, what's the recharging opportunity, and has does that interwork with the IP68 requirement. Really IP68? Submerged? Can the power pack part be disconnected from the wireless bit when not in use? Are there What are the size limits on the battery part?

 

The DMX over wireless isn't really that much of an issue, that's "just" ArtNET over the right set of Ubiquiti wireless point-to-point devices, in an IP68 plastic box, use the Ubiquiti link planner to confirm the link path, but what makes this approach possible is the power budget. If there isn't the power budget then this is a non-starter.

[Brian]

I'm a bit constrained as to how much detail I can put out but to answer some of the questions...

 

IP68? - yes, it really does need to be that, though not, as I said, when operating.

 

Power? - yes, battery would be fine as the operating period is relatively short. No more than 1hr will cover it.

 

Moving? - yes, the reception end will be moving, although within a constrained area. Something like a 30 degree beamwidth from the transmitter would keep the receivers covered. Worst case would be to go old-schooll and have someone pointing the antenna at the reception target area.

[pscandrett]

Moving? - yes, the reception end will be moving, although within a constrained area. Something like a 30 degree beamwidth from the transmitter would keep the receivers covered. Worst case would be to go old-schooll and have someone pointing the antenna at the reception target area.

 

If one end is moving, can you do a 'local hop' to a nearby basestation and from there 'up'link it using the highly directional antennae? (Or whichever way round it is). You then have a solid long-distance link and you can just cover the performance area in what you might call 'standard' coverage to account for the movements.

[J Pearce]

What’s the requirement on latency? Could you go via the internet using a vpn (or other similar tunnel) to a 4G endpoint? Edited September 5, 2020 by J Pearce

[the kid]

What’s the requirement on latency? Could you go via the internet using a vpn (or other similar tunnel) to a 4G endpoint?

 

 

My thought also, something like a pi controller and a hat that takes sim + battery pack. All that could be super small format battery can be replaced (or however big or small )

[dbuckley]

OK, a pair of Ubiquiti Nanostation AC should do it, I'm assuming you can get the fixed one 5m up, and the portable one at least 1m up, with unobstructed line of sight, with a path length of 5 KM, with quite a bit of leeway. The receiver, 24V battery, 3AH should do, and a Ethernet to DMX converter, and a voltage converter to suit the needs of the Ethernet to DMX converter, probably 24v->12V, all these go in a IP68 "plastic" enclosure, preferably with a transparent lid. Mount an IP68 RJ45 for DMX out on the box, and a IP68 power switch. Only downside is the need to unscrew the box to charge the battery, but this could be avoided by another IP68 rated connector exposing the battery terminals to recharge the battery. May want an inline 3A fuse on the battery because it's the right thing to do.

 

Not ridiculously cheap, but fairly easy to assemble using off-the-shelf bits from the likes of Amazon and RS. You never mentioned budget!

 

Do you actually need to send DMX? Would cues do? Timecode? There have been alternative solutions to this problem which use less radio-intensive solutions.

 

E2A - The Nanostations will almost certainly run on 12V rather than the 24V that they specify and that the included PoE injector supplies, so a 12V battery could be used, removing the need for the 24V-12> converter as well. So the ubiquitous 12V 7AH battery becomes the obvious choice.

Edited September 6, 2020 by dbuckley

[the kid]

This is the the reddit post I refereed to - quite a few ideas and options on mounting also -

 

[LostIn(this)Space]

Late reply. (Just joined)

 

The dirt-cheap 2.4G GMSK-modulation wireless DMX units will go a long way with a genuine line of sight. And you can get directional antennas cheaply enough too.

 

But mobile internet is a better option. A VPN means that you avoid the problems of changing public IP addresses and NAT.