Computing & Radar Displays - Computerphile

Key Takeaways

we've so far talked about the ibbm 920 which is this big beast up here and that really had two functions we've talked about flight data processing which is the information about what the aircraft intends to do but the other major facet of this is radar data processing so you can look at it point of view that the flight plan tells us what the aircraft intended to do the radar tells us what it's actually doing and they're not necessarily the same thing there's all sorts of reasons why the flight doesn't actually follow the the original Flight Plan uh it can be due to weather it can be due to congestion there's all sorts of reasons this was the first time we were able to bring the two together flight and radar data processing but that was all this did it just did the processing somehow we have to display all of that lot so we now totle over here um and this is an early example of a radar data processing system uh it's called the processed radar display system uh and essentially what happened was that radar information which is pure uh this is a a radar plot of this particular aircraft uh with no other real information associated with it would then be rooted to this equipment which would then be responsible for determining which controller needed to see it so effectively doing the rooting but then also down at the bottom here one of the world's earliest graphics cards a PDP 1134 which was just simply there in order to take the radar data and actually work out how to paint that onto the radar screen vector graphics drawn rather than raster drawn um and a very early example of of a graphics card and that in turn down a jolly great long cable would feed to this kind of a display here this is actually a slightly later display but it's the same sort of General type of display all that's in here is really the technology that's required to take the the graphics generated uh um positional data and actually paint it onto the screen these screens were outrageously expensive I I think they were in the tens of thousands of pounds back in the 1970s and they were also rather easy to break as well so we were always very very careful with these these are all different Radars that can feed in so you've actually got a switch up here that selects the different Radars and because this could be run in a what's called bypass mode so the control this is how we used to do in the old days the controller would select whichever radar gave him the best image for the area that he was trying to work on and those are the various on rout Radars so you'd have at least two of these screens sometimes more of them for each sector uh so this is a sector display how how big is a sector then a sector varies in size depending upon what's going on there's some sectors like for example the London TMA terminal move ing area which is really quite small because there's an awful lot of stuff going on uh as you get further and further a field so the sectors get larger and larger the other thing that can happen is the sectors can change shape between different times of day and so on so for example at night there's much less air traffic and therefore controlling it is much easier so you can make the sectors bigger and then as the traffic starts building up in the early morning as the flights start coming in across from the States you make the sectors back smaller again uh and that's something else which we were able to do as a result of introducing computers into it this idea of dynamic allocation of sector size which before then had been really quite difficult you might have heard of occasions when there's been a few hiccups with the air traffic control censers uh and usually it's to do with changing the size of the these sectors um but again the codee's been in there for a long time now I think we've got pretty well all the bugs out of it the controller would use this roller ball to for example highlight a particular aircraft and draw a vector to indicate how far away he would be in 5 minutes time was something like that this predates the mouse really but in fact in some respects it's probably a better system they are still using roller ball technology for radar display systems even to this day because it's in one place it never moves I was up at Prest control center just about a year ago and watched them using this to workout you so got a a radar paint sort of showing that the aircraft is such and such and and we know what speed he's going at so we can then draw a vector which says that's where he's going to be in 5 minutes time which allows him to see whether he's got any issues with collision avoidance or anything like that that and also to just to get the timing sorted out he's the controller is trying to Vector this aircraft onto the instrument Landing system so it's a useful idea if you can sort of say oh it'll be at such and such place in 5 minutes time or 2 minutes time or whatever so this is a very early example of of the of the radar display using the data from the IBM 920 that sounds ever so easy there was actually lots and lots of steps along the way and in fact it took many years before the radar ASA was really being processed by the IBM 920 and displayed uh in native form on this this type of display there was also bypass systems because like all of these things we don't want it failing uh so there's always there's always standby systems and standby to the standby systems and so on uh and a lot of that had to be implemented for the for the rad arst side of things as well how what's the sort of Refresh on something like that how often would it be refreshed well it's effectively being refreshed all the time because it's a vector graphics drawn system um but The Radars typically rotate one rotation every 4 seconds so you're going to get an update in terms of the radar data about every 4 seconds and what you actually see is like a little you see a blob where the aircraft is and coming off that there's a line and then a box and in that box you've got information about the aircraft it's altitude the aircraft uh call sign its type uh where it's going from where it's going to whether it's ascending or descending if you've looked at Flight Radar 24 they do a very similar thing that's using a thing called adsb which is a broadcast positional information system from commercial aircraft and effectively plotting that uh using servers and then you can pick that up on the Internet uh so and what they've done is they more or less followed the same kind of radar display appearance as you would have at a control center going back to our early graphics card over how many of those would there be in air trophic control I think it was something of the order of 100 so it was quite a big investment and a lot of real estate as well well how much were those sorts of things costing them I don't know to be honest I think they were probably in the quite a few thousand pounds each type of category so you know there would been there' have been large chunks of million pounds worth of of equipment there uh but back in those days Hardware was very expensive safety first as well uh yes the whole idea was that everything was resilient um so uh and of course this wasn't the only place we were using computers the computers were were coming into air traffic control in just about every every sort of capacity this is the kind of radar display that we have today and essentially all of the hardware that's required all the Computing and all the processing that's required for this sector is actually built into this play now everything's connected together with fiber optic uh networking isn't a problem anymore so we can actually afford to have the the processing out in the display other than that it's more or less exactly the same type of display it's still a vector graphics display because that gives you a better quality of of image um and the the screens are still outrageously expensive this is the sort of thing that they'll be sitting in front of at swanic there's also a brand new control center up at Prestwick as well which does from 55° North broadly speaking the Scottish border what's interesting to not is as another example of resilience uh is that the uh presswick with a certain amount of hassle could do all the work that's being done at swanic and swanic could do all the work that's being done at preswick it would take a bit of doing but if for any reason one or other of the control centers was unable to function uh then the whole of the air traffic control in the UK could be run from one or from the other one of the things that I decided I'd try and do was to write a game where the computer played Monopoly and you can see here the high-speed printers these printers would run at 600 lines per minute I wrote this whole thing in assembler the computer would make a move and it would then print the Monopoly board so this thing was throwing up Pages like mad and