Here is another part in the series where I’m discussing LED walls and how they work.
Today’s segment will talk about how you get a video signal from your source (camera, computer or other switching equipment.)
There are two major manufacturers and several others that are less well known. For the sake of today’s discussion, I will not get into all of the brand names but rather discuss the operation principals of them.
So the two main players are Novastar and Linsn. These are the OEM manufacturers of the processing equipment. Of these two Novastar tends to be the more favored processor here in the USA.
So as you saw in part 1 the LED wall is made up of many tiles and assembled into whatever size you want. In order to send the video signal to the panels, we need to have a data connection to each and every panel in the wall assembly. This is usually in the form of an RJ45 plug and a Cat5 or Cat6 cable.
Each panel (the typical 500MM x 500MM) would have a power in and out and then also a data in and out. So the physical wiring would be from your head end processor to the first panel in the wall, and then you would daisy chain the Cat cable out of the first panel to the second, and then the second to third and so on. This would continue until you hit the maximum pixel count of the output channel of the processor. In the last project I worked on we connected 30 panels together in series, then we started with 31-60 on the next processing channel of the processor.
The processor – for example, the Novastar NovaPro HD – has 4 “sending cards” which are the output channels. Each LED panel has one Novastar receiving card. In the software of the processor, you would assign the output channel to which LED panels you are connected to and which direction your wiring runs. (Top to bottom or side to side or spent another pattern) A sidenote here is that you don’t want to mix a Novastar processor with sending cards into a LED panel that has a Linsn receiving card. (or vice versa) In the rental and staging market this may come up from time to time and there are processors that can have both Linsn and Novastar sending cards in them…
The processor just needs to know the wiring order of the LED panels and then the image is automatically divided up into the proper LED panels. If you were to unplug the Cat5 from panel 2, then all the panels after that would lose signal. If you unplugged panel 5, but left 1-4 – they would work and everything after 5 would go blank. If you were to swap the order of cables on panel 5 & 6 your image would swap spots on those panels. And as for the numbering – the panels are not literally numbered or addressed such that you need to be concerned, my reference to number 2 is simply the second panel in the wiring series you create.
So the bottom line is that the sending and receiving cards talk to each other and are looking to be wired in order – and the rest is taken care of for you.
Some other benefits that can be had are the remote monitoring of the vitals of the LED wall. Novastar allows you to read the status of each and every panel with a computer hooked to their processor. You can also monitor the temperature – which is critical for maintaining a long life span for the LEDs.
Another piece of the processors is the video scaler. Most LED walls are not a standard number of pixels, so that requires some sort of scaling to get the image to fit the wall you are installing. This is where the quality of a high-end processor really makes a difference.
One more thing that has been asked is latency — this will vary with your processing, but generally, it will be 3-5 frames for most LED wall products.
More to come!! Stay tuned and keep asking questions. 🙂