The GEE Navigation System - a simple overview
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- Опубликовано: 7 окт 2024
- One of the most widely used radio navigation systems during World War 2 was GEE. This short video is a brief oveview of the theory behind the system. Once GEE was operational, Robert Dippy, the cheif designer then made a trip to the US to help with the design of the Loran navigation system; hence many similarities between the two.
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Very interesting - it brought back some memories. I trained as a navigator on Vickers Varsities in 1963 and used Gee II extensively. The last part of our training was in Meteor NF14s which had Gee 3 - much easier to use as it had counters rather than having to count the pulses. When the Vulcan first came into service it had Gee 3 later replaced by Tacan; the last one to be replaced at 230 OCU, the Vulcan conversion unit, was in Sept 1964.
Hi John. Thanks for the feedback! Interesting that you had so much contact with GEE over the years. This type of navigation aid might not have been as accurate or easy to use as a modern GPS, but at least it worked. We had one of the final versions of Decca on our boat (a few years back) and paired to a microprocessor it was surprisingly good, simple to use and gave a digital readout in lat. and long.
Hello, I loved the video, it was fascinating. I have never seen or read about the operation of the GEE system. However, I do have one. Well, to be truthful, the majority of one. I don't suppose it is of much interest to everyone but here is the story. I guess I was one of the original geeks with ideas far beyond my capability at that age. I spent my pocket money, first on the indicator unit. I don't really remember when, perhaps around 56 years ago, buying it from a war surplus market/scruffy shop in Blackpool. Then, without realising they were related, on the R1355 IF unit and an RF plugin. Of course, in those days there was no Internet and no information, probably it was still classified. I spent many hours tracing the circuitry trying to understand what it did ( I still have the notes). Now comes the sad part (for historical reasons), I removed the transformer from the receiver ( think it 4Khz) and built myself a 50Hz power supply using a war surplus huge hv transformer. I managed to power up the display for a while (before the rectifier blew) and could see some pulses. That was perhaps 50 years ago. Then it got left behind in the hurry to get trained, marriage kids etc. However, the GEE bits travelled with me and even grew a bit because I added some more front-end plugins; I think perhaps I have four different ones. It is in what is known as "unrestored condition" i.e. all the rubber insulation is hardened and some capacitors have been replaced by 1960 varieties. I even have spare valves (I think SP65 if memory serves me correctly).
So, there it has remained, untouched for around 50 years. It currently resides in my place in France, (where I am not 'cause of Covid) hidden in a dusty cupboard. I have kept it because, being born in 1945 I felt close to the 2nd world war and those who fought in it. OK, I treated Gee as a technical toy when younger but now I feel that it is a connection with those who flew pathfinders over Nazi occupied territory in the latter part of the war - well, perhaps I always had that in mind.
Hi Ray! Thanks for taking the trouble to spell out your personal experience with GEE bits :-) It still surprises me just how many relatively intact modules etc. are still being auctioned and sold - so many years after they were moved onto the surplus market. As for your transformer swapout, I think most have gone this way - including almost all of our stuff here. Shame your rect. failed, but was this due to something you did wrong or just an old component? I'm glad at least that you say you actually saw some pulses on your indicator. No chance of that happening now I fear :-( Whilst it sounds to me as if your stuff is pretty much as-sold, out GEE indicator had gone through a pretty rough time before we finally bought it with barely anything remaining from the original device. I think it was rebuilt into a VERY complicated oscilloscope which sadly, I am sure never worked properly. Some folks expect too much before they've even really started re-engineering something.
Glad you enjoyed the video! I hope you decide to dust off your own GEE equipment at some point to see if you can have it working again. BTW, do check out our LORAN video if you want to see the differences between the two systems. Remember that our Robert Dippy (who designed GEE) went to the US to help them complete Loran. - Our Loran APN-4 indicator being a hugely complex 100% ground-up rebuild when compared to our GEE variant! (There are I believe 22 valves inside!)
Great video; I wasn't listening well at first so I missed that the pulses were simulated; thinking surely the GEE system had been deactivated, but the video was so clean!
So, you had me going for a while there--LOL!!!
Really great that you went to the trouble to restore the GEE system then the extra mile to make the pulse-simulator.
The war was a very desperate time for England and so the sharpest minds were stretched to their limits. Truly Respectable! 73...
Thanks for the positive comments :-) Like Decca, it seemed rather silly to turn these navigation systems off when the world needs a reliable alternative to GPS. There is however (April 23) ELoran.. a modern equivalent of Loran, which is mean to be an alternative... Not sure how well its trials are doing though!
Like me, you're one of the verry few people to make the equipment actualy demonstratable.
Thanks for that, it's a verry niche hobby.
I agree. The whole philosophy behind the 'Radar Room' being to make things actually work, even if that means using artificially created data sources for items such as GEE, Loran and Chain Home, as they are no longer transmitted over the ether.
... aha! I have been reading into the GEE system recently and wondered if anyone had created a simulator. You’ve done it - brilliant! Most descriptions include a map view of TX chain locations showing the master A station located between the B and C stations, so I wonder if this was always the case. The final step, transposing measured time delay values from the screen to the chart to establish a fix, would have been really useful. I wonder what the full range of GEE units was? Presumably the 25\30 scale only covers a very small proportion of the possible measurement values. Finally, I’d like to understand the effect of real-world HF propagation on the usability of the system; i.e. with added noise and signal fading, etc at the limits of system range, how much of a challenge would using GEE be? Anyway, this is a superb recreation and thank you so much for engineering the simulation and sharing it via RUclips ... regards - Fraser
Thanks for your appreciative comments Fraser! Indeed it was a 'challenge', made particularly difficult by my being unable to actually see a real one working... (We contacted IWM Duxford for any help they could give us as they have one, but they were unable to offer any assistance..) Difficult to answer some of your other questions. I personally think that the system could have easily been made more accurate using modern circuitry techniques etc. As it was, I think it was surprisingly accurate for the year. Remember that the first signs of Decca were around during the early 40s as well and Decca went on to be used right up to around 2000 in modern microprocessor based units. We had a very small 'Dinghy Decca' on our boat for a few years and aside from a few drop outs around the Isle of Wight and around the Channel Islands, the system worked extremely well. I'm sure that GEE could have been 'revamped' in a similar way. As far as modern day interference is concerned, there could well be issues from many sources which seem to be missed by current regulations. A good example is those flashing Christmas tree lights adorning peoples properties in the festive season and beyond. Think - a long piece if wire up high with a nasty square waveform and a microcontroller hanging on??
Brilliant description Chis best Clare
Aw.. Thanx Clare! :-)
Very good, thank you! I read the Wikipedia page on Gee but could not understand the display and the nav reading. (The traces on the osc. photo in the Wikipedia page are simply painted on!) The map whith the red and green hyperbolas is also very helpful. I would recommend to read the Wikipedia page though to better understand the theory of the system.
Pleased to be of help. I agree that it certainly helps to see an actual working display, rather than a roughly drawn chinagraph representation!
That's nice but...how to you plot these screens info to the nav chart?
It is a lot easier to work with than with Loran for starters, as GEE only used ground waves. The charts used are specially printed with hyperbolic curves already drawn on in three colours. Each colour representing either slave B, C or if it is present, the D slave. The reading is therefore taken straight off the display by counting the pulses from left to right, (for each line), then each of these readings is applied to the chart using the appropriately coloured curve. Each of the coloured curves being easily identified by the numbers printed on them. These are shown as GEE units, as opposed to actual timings as-per Loran. (A GEE unit being 66.67uS) I hope this helps a little!
@@lishaton In the absence of a graticule or countable pulses, it's not clear at 4.38 how the positions of the pulses are then transferred to the fine lines off the chart. It's plain from other commentaries on this navigation system that it was accurate enough to use for 'blind' landings in very bad weather. Did the unit itself give an accurate numeric output? Or were the various dials calibrated in some readable way?
In essence, GEE is sort of a different form of LORAN
Indeed it is. GEE is the more accurate of the two, but Loran works over a much larger distance.
When did the Americans start using this system
I'm not quite sure Mark. With the war in the Pacific, they needed to fly longer distances, hence the Loran system was developed However, GEE was more accurate, albeit at shorter ranges. My guess is that they started to use GEE when they started sending their bombers over here to help the RAF. I have a couple of 'photos of both GEE and Loran being used alongside each other in a B17 which suggested it was a case of choosing the one most suitable for a particular raid?
You REALLY need to do something with your audio. The noise and "SS 'SS" from your voice nearly over-rides the intelligent speech, and the fact that you have an accent and speak very fast does not help. This could have been a VERY interesting and informative video
Apologies. Comments noted.