Times wireless DMX has failed

I know I initially had the cheap silver tube direct plug-in receivers but pulled them and replaced with a little black box with a short DMX cable coming out...I can't think of the brand name but I thought it was the WDMX system.
That sounds like a wicicle and then a Chauvet D-fi. But thats just because I know those fit the description.
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We had a designer come in for a show that wanted to add color to the houselights at a large regional theatre. The building wouldn't allow them changing the lamps in the architectural sconces, so the designer added 24 3" fresnels within the wall to shine up at the wall sconce. Those plugged into an orchestra stringer and into a small dimmer pack with ShowBaby wireless DMX.
So 24 lights in 8 locations and show baby to control.
What would happen every other show or so is when house would go to half, none of the colored lights would fade out. Then randomly into the act, they'd blink out.
Every time, they'd be ok fading up, I assume because everyone's phone had been in their pocket for an hour during the show, but fading out was always a mess.

This one sounds a lot like TX/RX placement. What was the placement of the RX and TX? Where there a lot of bags of water (people) in between the two? We ran into a very similar issue last year where the RX was in the trap room and the TX was on the balcony rail. Popped on a directional panel antenna and it was fixed.
 
I've had several experiences with at least somewhat "higher end" wireless DMX ranging from "not good" to "fine"

First, (and yes, this was a while ago) about 12 years ago, the prior director in my space decided he wanted to add a few more conventional dimmers. He brought in a company that speced some ETC SmartPacks (fine)... but for electrical/wiring ease, decided not to install them in the current breaker room, rather, place the SmartPacks in the boiler room where the main electrical distro for the building was. This was ~150+ feet from the breaker room, behind the stage, etc... not an ideal location. So, for what I also assume was ease, they speced a WirelessDMX (brand) WDMX setup rather than run true DMX to that location... This was a very high end WDMX unit, that was "one of the best" at the time (do not remember the specific model, again... 12 years ago). In short, while the distance wasn't anything ridiculous, this boiler room was behind a double-thick concrete block fire wall with 2 layers (yes, 2...) of sheetrock on both sides. Not to mention other electronics, pipes, equipment... and then people, when the space was full between the transmitter and receiver. In the end, it never was 100% reliable (ghosts, "no DMX" on the rear units, etc.), and so we went back to the installers who "tweaked a few things," but in the end, took back the whole WDMX system, and ran a couple hundred feet of DMX. The WDMX of the time left us feeling like we couldn't use those dimmers because they were "unreliable."

Second experience with decent equipment was just last year with ETC's ColorSource Relay system. My institution had a old lecture hall renovated, and in the process, installed basic theatre lighting. The installers speced a ColorSource relay between the electrical room, and the lighting battens. It worked fine until we installed several wireless AP's in the space, then I got reports of ghosts every once in a while. After a wireless survey, and tweaking some things with the wireless (I also work in IT), I've heard of no issues. Again, this is basically a lecture space, not a main stage theatre.

Because of these two experiences, I'd personally be reluctant to use wireless DMX for anything but a needed effect. I have a former colleague who recently put together a whole wireless rig in a wagon, using car batteries, an inverter, wireless DMX, and a fleet of HotBox's. While I didn't work the show, I saw the result and it was all rather slick. I heard they ultimately had "very few issues," and it has made me think about trying it all again.

Again, my negative experience(s) have primarily been in situations where (in my opinion) they were trying to do the job that a wired connection really was called for. Also, I'm sure the technology has evolved considerably from the equipment I was most familiar with over a decade ago. That said, I was using high-end stuff for the time... and it still wasn't cutting for my need. Clearly there are amazing instances of wireless working great.
 
My bad experiences have been with an old eDMX Tube system that was released by Avolites. It was a 2.4GHz WiFi based system. It could operate off of an installed WiFi access point or as a stand alone system.
The first problem happened when we added a bunch of LED strips for some flash and trash. Rehearsal was fine. Fill the house with 1200 teens and the system bugged out. The wireless access point was at the rear of the house by the board. Direct line of sight to the stage, but a whole lot of bodies in the way all with smart phones affected the signal. After that, I always used the system as a stand alone system and placed the transmitter closer and well above head height.
The second problem was last year. Outside for the lighting of the Christmas Tree by city hall. Same set-up as the last few years. Console at front of house. Transmitter on top of the adjacent truss. Receivers on top of booms by the stage. Last year everything was working...until. Part way through the event, I lost communication to the LEDs by the stage. I thought maybe the receiver had gone bad. I pulled out my phone and checked the WiFi. There was an SSID for the ambulance company that was onsite. When they showed up it, the ambulance's system overpowered my wireless DMX. When they pulled away after the event, sure enough didn't I get my control back.
As has been noted, the 2.4GHz spectrum is flooded right now, the 5.3(?) is the next to get flooded. 900MHz is looking good to me!
Take care,
John
 
This one sounds a lot like TX/RX placement. What was the placement of the RX and TX? Where there a lot of bags of water (people) in between the two? We ran into a very similar issue last year where the RX was in the trap room and the TX was on the balcony rail. Popped on a directional panel antenna and it was fixed.
Oh yea, it totally was receiver location. Since they had to hide the lights as best as possible, they receivers were just strung wherever.
 
Just a reminder for people putting in wireless DMX.

Put the transmitter *on stage* if you have the cable. Wireless isn't about distance, it's about "no hanging cables".

It's just like wireless mics: you put the receivers on stage, if you can.

Also, someone makes -- and it's only a couple hundred bucks -- an actual spectrum analyzer that goes USB into your laptop; looks like a wifi dongle, but the software will do a full sweep.

That will *show* you the difference between rehearsal and performance.
 
Spectrum analysers are great. There is a basic app just uses the devices 2.4 radio.

I'd love to see a set (4-6) of devices that actually pass data and log the results over a week or so. Place them as planned in a space and get quantifiable evaluations of reliability and band width.
 
OK so I have had one failure of wireless DMX. I had it attached to a smoke machine. Now the problem was once the smoke machine was working the wireless signal dropped and because the smoke machine was remember last state when DMX dropped it kept going and going and going. Filled the stage with so much smoke. The only saving grace on this occasion was interval at the end of the scene where we could then stop the smoker. Now my wireless triggers are configured to drop state to off loss of signal.
Fun times.
Regards
Geoff
 
I'm curious if yagi-to-yagi with horizontal polarization has ever failed for DMX. I would think it would be reliable considering that higher power omni-directional sources of interference usually have vertical polarization and would usually come from other directions if the transmitter is placed high.
 
It's not just theory now, I can say from an experiment in a dense urban environment with lots of WiFi that horizontal polarization is the way to go, even if it's just monopole antennas, and putting a yagi on the receiver offers some additional benefit. Tests with City Theatrical Show Baby 6:

- Two 5dBi vertical monopoles: flickering 1st LED of signal strength, DMX did not work. Unfortunately I forgot test tilting the antennas a little to compensate for elevation difference.

- Two 5dBi horizontal monopoles (parallel to each other and perpendicular to line-of-sight): solid 1st LED, flickering 2nd LED. DMX worked reliably in a brief test.

- 5dBi horizontal monopole on transmitter, horizontal yagi on receiver: solid 1st and 2nd LED's. DMX worked reliably for a couple hours of programming.

The disadvantage of horizontal polarization and reason vertical is more common is that it usually only works with 1 receiver. I did not get a chance to test the original antennas (I believe they are 2dBi) that came with the Show Baby's but assume they would not work as well.
 
H-pol has no inherent problem with multiple receivers. V-pol is popular because it it relatively easy to create gain towards the horizon by reducing the gain above and below the antenna. We live in a world where the flat-earthers are nearly right!

Having a directional antenna on a transmitter is a problem if it isn't pointing at the receivers.

If the receivers are "everywhere" then an omnidirectional transmitter antenna in the middle with directional receiver antennas pointed at it is a solution (if there is a problem with omni rx antenna)
 
I meant to say what you said. Basically the radiation pattern limits where you can place receivers. If a receiver is high on a truss and another receiver directly below it on the stage that would work with h-pol.

There's a guy in Amboy, CA (a couple hours from me) that built a steam-powered rocket to fly up and see how flat the earth is. He couldn't just take an airplane flight and carry a watch or go to the beach and see boats sail away in the horizon. I think the mountains nearby were about the same elevation that his rocket reached, and I imagine during his brief flight he had to focus on not dying on the way down rather than making scientific observations.
 
Any care to give us a 101 primer on what any of this means?

If you want to dive down the rabbit hole further, the keywords to search for are "antenna polarization."

I'll just simplify linear polarization and we'll not worry about circular polarization, mostly because I don't know too much about how that one works.

Simply put, the way that antennas radiate polarizes the RF (the electrical and magnetic fields are perpendicular to each other, the electrical field being parallel with the antenna wire and is the field we care about for this) in whatever plane the antenna is in. Two antennas that are both in a vertical position will be able to talk and listen to each other quite easily because the polarization is matched up.

If you took one of those antennas and turned 90 degrees so that it is now horizontal, the two antennas would have a much harder, if not impossible, time talking to each other because now they are polarized differently since one is vertical and the other horizontal.

Think of it like taking two pairs of polarized sunglasses. If the polarization matches, you can see. If you turn one pair perpendicular to the other, you can no longer see.

A yagi is an antenna that is designed in such a way that it pushes the antenna gain strongly in one direction in order to increase the range that said antenna can talk to and listen from.
 
I'm catching up on a couple months of posts, and I particularly enjoyed this discussion on wireless DMX - https://www.controlbooth.com/threads/wireless-dmx.44193/

Something I would love to hear is the times where wireless DMX DIDN'T work as planned. This isn't to diss on the manufacturers, who make great products that meet a great need. But we all learn more from failure than from success. And wireless has some tricky points of failure.

So I'm curious what setups worked 99 times and then just failed on that 100th time, or worked great in rehearsal but not when the house was full, or worked until the welder across the started welding, etc.

I wasn't on site to confirm it but I was told that an event for a foreign dignitary here in the US had Secret Service show up and shortly thereafter all 2.4 GHz in the area was knocked down by Secret Service equipment. The person I talked to about this event told me he ran wireshark after scrambling to run cable, and he saw only 2 things visible in 2.4GHz. They were named SS-178 and SS-179. Take it with a grain of salt, but I would have no doubt that Secret Service knocks down 2.4 in the interests of security in an area where they are protecting someone.
 

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