Computing & Radar Displays – Computerphile

Computing & Radar Displays – Computerphile

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We’ve so far talked about the IBM 9020 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 from the 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 original flight plan 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’ll now toddle over here and this is an early example of a radar data processing system. It’s called the process radar display system, and essentially what happened was the radar information which is a pure radar plot of this particular aircraft with no other real information associated with it woud then be routed to this equipment, which would then be responsible for determining which controller needed to see it so effectively doing the routing but then also, down the bottom here, one of the worlds earliest graphics cards! the pdp1134, which was just simply there to take the radar data and actually work out how to paint that onto the radar screen vector graphics drawn rather then raster drawn and a very early example of a graphics card and that in turn, down a jolly great long cable would feed to this kind of display here… this is actually a later display but it’s the same type of display all that’s in here is really the technology that is required to take the graphics generated posistional data and actually paint it onto the screen. These screens were outrageously expensive, I think that they were in the tens of thousands of pounds back in the nineteen seventies and they were also rather easy to break aswell 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 all the different radars and because this could be running what is called bypass mode and this is how he used to do it in the old days, the control would select whichever radar gave the best image for the area that he was trying to work on and those are the various en-route radars so you’d have at least two of these screens, sometimes more of them, for each sector so this is a sector display. How big is a sector then? a sector varies in size depending on what’s going on there’s some sectors like for example the london TMA, terminal moving area which is really quite small because there’s an aweful lot of stuff going on as you get further and further afield 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 is much less air traffic and therfore 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 from across the states you make the sectors back smaller again and that’s something else 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 a few occasions when there’s been a few hiccups with the air traffic control centers and usually it’s to do with changing the size of these sectors but again, the code has 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 five minutes time or 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 prestwick control center just about a year ago and watched them using this to work out so they’ve got a radar paint showing that the aircraft is such and such 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 five minutes time which allows him to see if he’s got any issues with collision avoidance or anything like that and also just to get the timing sorted out, the controller is trying to vector this aircraft onto the instrument landing system so it’s a useful idea to say, it’ll be at such and such place in five minutes time or two minutes time or whatever. So, this is a very early example of the radar display using the data from IBM 9020 that sounds ever so easy, there was actually lots and lots of steps along the way in fact it took many years before the radar data was eally being processed by the IBM 9020 and displayed in native form on this type of display, there was also bypass systems because, well like all of these systems we don’t want it failing so there’s always standby systems and standby systems to the standby systems and so on and a lot of that had to be implemented for the radar side of things as well. What’s the sort of refresh on something like that, how often does it refresh? Well it’s effectively being refreshed all the time because it’s a vector graphics drawn system but the radars typically rotate one rotation every four seconds so you’re only going to get an update in terms of the radar data about every four 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 its altitude, the aircraft call sign, its type, where it’s going from, where it’s going to, whether it’s accending or decending if you’ve looked at FlightRadar24 they do a very similar thing it’s actually using a thing called ADSB which is a broadcast posistional information system from commercial aircraft and effectively plotting that using servers and then you can pick that up on the internet and what they’ve done is they’ve 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, how many of those would there be in an air traffic control center? I think it was something in the order of one hundred 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 there would have been large chunks of a million pounds worth of equipment there but back in those days hardware was very expensive. Safety first as well. Ah yes, the whole idea was that everything was resilliant, so and of course this wasn’t the only place we were using computers, computers were coming into air traffic control in just about every sort of capacity. This is the kind of radar display that we have today and essentially all the hardware that is required, all the computing and processing that’s required for this sector, is actually built into the display now everything is connected together with fibre optic, networking isn’t a problem anymore so we can actually afford to have the processing out in the display other than that, it’s more or less the same type of display, it’s a vector graphics display because that gives you a better quality of image and the screens are still outragously expensive. This is the sort of thing that they’ll be sitting in front of at swanwick there’s also a brand new control center up at prestwick as well which does from 55 degrees north broadly speaking the scottish border. What’s interesting to note is, as another exaple of resilliance, is that the prestwick, with a certain amount of hassle, could do all the work that is being done at swanick and swanick could do all the work that is being done at prestwick. It would take a bit of doing, but if one or other of the control centers was unable to function, then the whole of the air traffic in the UK could be run from one or the other. One of the things that I decided I would try and do was to write a game where the computer played Monopoly And you can see here the high-speed 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.

36 thoughts on “Computing & Radar Displays – Computerphile

  • Top 10 Stuff Post author


  • Kunal Booch Post author


  • Oskar Karlsson Post author

    excellent video, I say 3min after an 8min video is released

  • MrAntieMatter Post author


  • Andrew Joy Post author

    3.5inch floppy fancy pants stuff right there . And a PDP working along side an IBM , controversial.

  • 02) 5-15min Post author

    under 200 club

  • Pookie Pook Post author

    I wanna see that ATC Tower Simulator or I'm un-subbing. xD

  • Vamshi Darisi Post author

    under 500 club

  • Andy Post author

    You say rooter, I say router. Surprising to me I hear this all of the time it must be the standard everywhere but the US.

  • Lester Bailey Post author

    The Sony 2K monitors, as used at Swanwick/Prestwick, are not vector graphics displays.
    The PDP11/34s were more than a 'graphics card' they were Radar Display Processors which handled selection of the required radar data streams from the 12 odd available and also handled the inputs from the various control panels on the controller suite. The 11/34s originally drove as Sector Equipment Group which converted the digital data to vector data to drive the original displays, once the Ericsson displays where introduced they had the SEG functionality built in and were therefore driven directly by the 11/34.
    Ex Head of RDP Workshops West Drayton 🙂

  • Peter Taylor Post author

    2:00 as in claxby, lincolnshire?

  • Sir Alfred Powell Post author

    Phist, anyone?

  • CandyCreep Ent Post author

    Why is the "mouse" on the left side, since most people would like to use their right hand?

  • Der Mathze Post author

    Am I the only one who thinks he talks a bit like Lester from GTA V?

  • Copydot Post author

    I wonder, can the Air Traffic Control radars "lock on" to an aircraft like a fighter plane does to get more data on it?

  • ElagabalusRex Post author

    I'll admit it: I'm disappointed that the modern plan position indicators don't have the glow and fade of their analog predecessors. Computing technology has come far, but was it worth it?

  • LunchBox Post author

    please more of radar and computing <3

  • Jordan Franck Post author

    I think even the Computerphile guys' minds would be stumped by why this video has dislikes

  • Laura Halliday Post author

    Cool. I've seen some of the hardware Nav Canada use, and it looks similar. It was almost a letdown to visit the ACC earlier this year and see that Vancouver Terminal was two people and three computer monitors…

  • spankmeister Post author

    Is this a new display at TNMOC? I don't remember it being there when I was there a couple of years ago.

    Thankfully I'll be visiting BP and the NMOC at the end of the month. 🙂

  • James Grimwood Post author

    So where are the radar that collect information about the aircraft? Are they all based in London, or spread around the country?

    What I'm trying to figure out is how people sat in a room in London could see what planes 200 miles away were doing. Today we can just shovel that data in realtime down the Internet, but what about in the 70s?

  • evildude109 Post author

    I'm wondering what exactly is meant by a "vector display". Surely the final product has to be cut into rasters eventually?

  • Propane Post author

    Thanks to everyone involved in making these Computerphile videos. I enjoy them a lot.

  • Samir Oucherfi Post author

    Love seeing mid to late 20th century tech ! It's all so beautiful.

  • Jasc Tomm Post author

    8bit guy and Techmoan should TOTALLY put that radar display to work again.

  • detaart Post author

    He says the new displays are vector, but i can definitely see the raster.
    CRTs are the only way to do vector really. And that's not a CRT …

  • TechyBen Post author

    They used rollerballs? We are all doomed! (sarcasm ;p I guess you cannot drop it like a mouse)

  • mcol3 Post author

    Why does he talk about image quality when only little green dots are displayed?

  • T Trindad Post author

    The "mouse" is actually called a trackball, and it's actually still used. A lot of people prefer that in order to avoid carpal tunnel problems caused by working with a mouse.

  • IstasPumaNevada Post author

    These were quite interesting. Thank you.

  • Benjamin Philipp Post author

    0:27 "…it can be due to ingestion"…? O.o
    There is something out there that eats planes?
    D: I'm scared

  • Jolly Joy Post author

    why cant the guy the camera steady? or use stabilized camera? or do stabilization in the editing?

  • Ricky Oswald Post author

    Is Ventnor miss spelt on that machine?

  • John Lofgren Post author

    Need a lesson in British English, please… Why is the "w" silent in Swanwick, but not in Prestwick?

  • rhamses Post author

    Awesome video. It's always nice to see how hard working was back then and how far we've got. It cast a little of perspective in my mind.

  • Manish Upadhyay Post author

    Sad that company like DEC, introduce system like PDP ran out of business. The ease of using internet and internet protocol's (DDCMP) emerged from the efforts of such company's. 🔭 They will always be Legends. ✒️

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