Bawdsey Manor: The Birth Place Of Radar
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- Опубліковано 16 вер 2024
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We used to land at an LZ in the vicinity of Bawdsey back in the early 2000s when I was an MH-53M flight engineer. This video takes me back almost 20 years; 21 Special Operations Squadron, RAF Mildenhall. Thanks Cap.
What a neat looking museum. Wasn't aware this place existed. Haven't watched the whole vid yet, but I've added this my watchlist. To add, Dungeness is in Kent. The sound mirrors pre-dated radar. You had observers listening at the focal point and they could hear the planes crossing a preset point and height. Cool vid.
If you think of it like how DCS thinks of radar beams, the Amplitude on the A scope is the "Brightness" of the return and the depth is the "size" of the return. On a big dipole system like this each station transmits their waves, in this case like a light bulb filament. it just sort of comes out of the arial wire in all directions. When it hits a target the beam gets scattered and is "illuminated" each receiver in the 4 monopole antenna array picks up that Illumination each slightly out of phase of each other. So from that you get a basic Bering by sticking it through something called a Radio Goniometer which "adds" the 4 received signals to "point" which way the illuminated signal is "brightest". With this system you then took multiple receiver Station's bering and zeroed in on the position (because one station would basically give you a big approximate blob) so approximately how you drew it, but they didn't need to draw the whole circle because each station would get a rough direction. The filter room then took all the raw plots from all the radar operators and resolved a more exact position which was then combined with ALL the Filter Plots to give a big picture.
Altitude is harder to understand, it has to do with how the ground interferes with the signal and how a second perpendicular set of antenna angled at two slightly diffrent angles pick up the signal differentially then math happens.
Moving scanning dish make way more sense than a fixed antenna arrays. Radio waves act weird.
A radio Radio Goniometer was used and the eight aerials it used were on the 4 towers on the receiver part of the same station. The Receiver aerials were fitted with reflector dipoles so they were semi directional. The towers were in a rhombus shape with one pair of towers on a North / South Axis and the other pair on a East / West one. The reflectors on the Receiver aerials meant that the aerial on the north tower would get the strongest return if the target was to the north, the east tower from the east and so on. Elevation was measured between 2 sets of aerials separated by around 120 feet in height. The system was engineered so that Goniometer was used to find the lowest peak of a signal on the CRT that the operator wanted bearing and elevation of by flicking a switch which set the receiver to select how the aerial signals were fed into the Goniometer. Chain Home was built the way it was because there were no Transmitters at the time capable of giving a 120 mile range at frequencies high enough to allow a small enough mechanically turned scanner to be built
I served at RAF Bawdsey 1967/68 as a JT radar engineer mostly on the Type 84. Icould tell you a lot more but I'm still subject to the official secrets act.
How CH (and CHL) was operated from an early 1941 RAF operators manual. 21 CH stations were fitted with the electro-mechanical calculator before the start of the Battle of Britain.
C.H. Station Operations Staff
1. Observer. This Radio Operator sat opposite the cathode ray tube wearing a Head and Breast Telephone Set and observed the echoes on the tube. He dealt with them in turn starting with the echo nearest the ground ray on the left-hand side of the tube. He first sensed the echo to determine whether the aircraft was in front or behind the C.H. station and then side-sensed it to decide which side it was of the line-of-shoot. He then placed the manually controlled range pointer on the left-hand edge of the echo and took a bearing by swinging the goniometer until the minimum signal strength was obtained. When the operator pressed two switches which actuated the electrical calculator this caused a grid reference (controlled by the settings of the positions of the range marker and the goniometer dial) to appear on an illuminated display panel situated in front of the teller.
The Observer then switched to the height aerials and repeated the performance, causing a height to appear below the grid reference. A further set of switches indicated the estimated number of aircraft in the raid. As soon as the complete set of information was displayed the Observer announced the name of the R.D.F. station by telephone to Stanmore Filter Room followed by the track number or identification and I.F.F., if showing.
2. Teller. The Teller continued with the plot, speaking on the same common telephone line, giving the number of aircraft, the height and the grid reference of the plot as shown by the plotter. The Teller also gave plots by reading off the C.H.L. record sheet, giving priority for this over C.H. plotting. The Filter Room plotter repeated back all the information as a check to the Teller.
3. C.H. Recorder. The C.H. Recorder recorded on loose sheets every plot registered on the electrical calculator, noting the time of the plot, its number, height (if any), friend or foe and other relevant information such as the number of the raid allocated by the Filter Room at Stanmore, the fade and pick-up ranges, signal-noise ratios, the equipment in use, interference, the time of the last range calibration and any Filter Room remarks. These records were sent to Stanmore daily for record and technical investigation purposes.
4. Plotter. The plotter sat before a large grid-reference map and plotted all information passed to Stanmore, so that if a query arose, the Supervisor had a picture of the recent activity. C.H.L. tracks were also plotted in a different coloured pencil to distinguish theirs from C.H. plots.
5. C.H.L. Recorder. The C.H.L. Recorder sat next to the Teller and recorded all C.H.L. information, having an open line to the associated C.H.L. station for receiving plots. The C.H.L. Recorder also took up any C.H.L. queries from Stanmore Filter Room.
6. N.C.O. in charge of the Watch. He was the N.C.O. link between the officer Supervisor and the Radio Operator A.C.s or A.C.W.s. It was part of his duty to see that each member of the watch did his or her job efficiently. He also kept the operational log for the station and generally assisted, sometimes as an Operator,
in maintaining the smooth running of the watch.
7. The Supervisor. The Supervisor was a Flying Officer or Assistant Section Officer (W.A.A.F.} Radio Specialist. This officer was in charge of the watch and had much experience in interpretation of R.D.F. information on the cathode ray tube. He or she was the most experienced person on the watch and was therefore invaluable in sorting out the observed echoes and maintaining a smooth organisation for which he or she was directly responsible.
C.H.L. Station Operations Staff
1. Observers. There were two observers as two cathode ray tubes were used; one watched the Range tube and the other the Azimuth (or bearing) tube. The observer at the Azimuth tube operated the receiver aerial by hand, rotating it, since C.H.L. vision was beamed like a perpendicular slice compared with the C.H. station radio "floodlight." It was therefore necessary to sweep continually to search their -area. Otherwise the duties, including those of the Range tube observer, were similar to the C.H. observer.
2. Plotter-Teller. He plotted the information spoken by the observers and told it to the C.H. station. The plots were not a record as they were marked on a celluloid-covered map and rubbed off periodically, only being needed for identifying tracks and answering any queries raised by Filter Room through the C.H. station.
3. Recorder. This airman recorded all plots as told by the observers and plotted by the plotter-teller. The record was sent to Stanmore for analysis.
4, Corporal Supervisor. This junior N.C.O. supervised the watch. He was responsible for clearing up queries and for assistance in the identification of echoes. He was directly responsible for the smooth running of the watch.
Both C.H. and C.H.L. stations had a complement of Radio Mechanics responsible for the day-to-day serviceability of the stations. They were also capable of acting as observers and usually assisted during their tour of duty.
Just went to the museum a few days ago with the PGL! Was really fascinating and learnt a lot about the first radar tower.
cool man
Excellent video. Thanks for taking the time to do it Cap. I’m definitely going to have a look at this place the next time I am in that neck of the woods.
Magnitude of a radar return signal is a function of output power, range and radar cross section from the angle you're looking from.
As the plane turns sideways, exposing a big surface, you'll get a stronger return.
Microprocessors aren't needed for correlating the signals from multiple receiver towers, however analog solutions require more far more complicated and expensive hardware.
It will also need a lot of skilled work on each station to tune said hardware, and even far more skilled if the positions of the transmitter/receiver towers don't follow some geometric pattern.
This would likely be spent elsewhere, such as by the code breakers.
The accuracy of the azimuth will, with this method, be limited by the angle between the receivers from the target. (Also relates to which radio band/frequency they're using.)
This could leave you with a huge search area.
Using several sites can increase those angles to the >15 degrees range, at which point it is very precise.
This is also much easier, merely transmitting "at 15:02:30 it was 64.3 miles away" from 3+ stations, drawing out those circles for the same time, and plotting the contact at the intersection.
So that's probably what they did.
Depending on altitude, you may also get variation in the ranges between them, which will make the intersection an area rather than a point, and the size of this area can probably be used to estimate altitude.
See also
www.radartutorial.eu/01.basics/Angular%20Resolution.en.html
though that assumes a single directional antenna. The omnidirectional antennas of chain home would be closer to
www.radartutorial.eu/06.antennas/Phased%20Array%20Antenna.en.html
Thanks Sir
That giant vacuum tube(Or valve, as you guys call them.) was cool to see. I'm betting you probably didn't want to be anywhere near that thing when it was operating. High energy tubes give off x-rays as side effect. You'd probably glow in the dark standing next to that in operation, lol. But really, I love when people like you can get this stuff on UA-cam. So much of this kind of thing over in Britain I'd love to see but I highly doubt I'll ever have the chance. So I really appreciate it when you guys take the time to do it.
Wow awesome
Not these ones!!! Power and Frequencies were not high enough. Go up to 10CM wavelength on the other hand and you will get X-rays off the thing if the electron beam in it is not focused correctly.
I'd read about Chain Home and seen a few pictures of antennae and such but I had NO idea how extensive it was or the vast effort to discern usable data from it. Great vid CAP!
41:21 I'd assume the amplitude is signal strength, yeah, they wouldn't really have had any sort of advanced processing to get anything else out of it, and the clutter at the start looks like signal strength.
In theory it would be possible to use that, combined with the distance, to figure out the radar cross-sectional area of what was bouncing the signal. The resolution would be too bad to get any sort of precision out of it, and there's a number of variables which go into that, but an operator could probably tell a small patrol of a few fighters apart from a large force of incoming heavy bombers, for instance.
54:24 The people you were talking with seemed inconsistent about whether or not they could get a bearing from a single station... while your hypothesis about being able to get a bearing from the slightly different range to each of the receiver towers is correct, I'd agree the technology of the time wouldn't have been accurate enough to do that with stationary omnidirectional transmitters and receivers. In theory something could be done with phase-shifting the different signals by variable amounts and using interference patterns to compare them, rather than using the extremely precise timings which would be required to measure a distance that small with enough accuracy, but I don't think that would have been in such an early system.
My guess is the same, they couldn't, and it was done using the range from multiple stations, hence why they built so many of them. Technically using 2 ranges the plane could be anywhere in a large vertical circle where the two spheres intersect, but you could certainly use some assumptions about where the plane is likely to be (though I bet the first V2 signal confused them!) to figure out a rough position. If they had more (ideally 4+) ranges, the position could be as precise as the technology behind the ranges would allow.
It's certainly possible it got upgraded at some point, or other stations were built with different setups, and both options are true depending on the timeframe. If either the transmitter or receivers weren't omnidirectional and could rotate, or even rotate a masking shield of some sort around them to make them that way, then yes it could absolutely be done fairly accurately from a single location with only vacuum-tube-level technology.
Chain Home AMES Type 1 in 1939 could determine Bearing and Height from a single station! The four Receiver towers were fitted with a pair of aerials on each one (one at 215 feet and one at 95 feet above the ground), the eight outputs of each where mixed in the Receiver via switches and a device called a goniometer. The Operator adjust the control of the the inputs of the goniometer by the switches to configure the display on the CRT to determine either bearing or elevation by the mixing of the signals from the 8 aerials. Then by turning the control on the goniometer, they adjusted the signal displayed on the CRT so that the peak of the signal of the return they wanted the information of was at a minimum. They then read the angle at which the pointer on the goniometer was at (the control had a angle scale on it). The main issues with the system in 1940 were none of the radars had been calibrated fully and that a lot of operators were newly trained and not experienced enough to be able to use the system to its best accuracy.
interesting stuff, we have a site near me in Cornwall, Nancekuke where they produced nerve agent Sarin. Rumors say that they even dumped it local mineshafts.
Good introduction, Cap! Here is a starter for ten on behalf of Airborne Radar: alanblumlein.com/h2s-airborne-radar/
By one of those strange coincidences Alan Dower Blumlein was also the inventor of Stereo sound whilst working pre-war at EMI. This probably contains the hint that both required signals to be in phase with each other (amongst other things). If I remember Abbey Road had a memorial to him but it may have been at EMI's Hayes site (memory failure). Good hunting! Best, Pete.
thx Pete
Very interesting video, Cap!
I love seeing about the development of military technologies like these, and radars are particulairly interesting for some reason, I'm finding.
Now, I heard you get confused at about 20 minutes into the video about having radars on some WW2 planes, and yes, various planes in the war did have radars on them.
I don't know much more than the fact that they did have them, however, so I can't tell you much about their effectiveness, specifications, or how they worked back in that time.
What I do know is that while they developed very quickly and could indeed fit in aircraft quite early on, they could only be fitted on larger aircraft such as bombers or attackers, that had the space, strenght, and engines powerfull enough (for electricity) to facilitate the radars. So they obviously couldn't fit on Spitfires, back in the day.
I do know that the Brits also used radars to great effect in WW2 on maritime patrol aircraft to find and destroy German U-Boats, and that the Germans later even nicked a surprisingly capable RWR-like device from the French to warn them of incoming aircraft. (Which then lead to the development of the Leighlight and much more historical stuff that won't fit in this comment, involving the war against U-boats)
As for the question in the end of the video
No, I highly doubt that one radar sight could triangulate the position of enemy groups independently.
In order to find the bearing of a target with a single radar you would have to focus and steer the radar beam by physically moving the antenna or moving the beam on an electronically scanned array. And it looked like the antenna's were completely fixed, and they obviously didn't have the technology for ESA's back then.
As the man explained in the museum, the range would be interpreted by an operator looking at the signal bouncing back on a screen, by looking at where the signal appeared on the scale. But since the antennas would only be a few acres apart, the signal on that scale would also only be a few acres apart, at best, which would be quite difficult to read off on that display, I believe. (Not even factoring in the accuracy of the radar) So even if you were to read off a range deviation from the diffirent antennas you would only get a very rough and totally insuffient estimate of the bearing.
Very interesting, tho! I'd love to see more about the technology behind the stuff!
A Chain Home Radar could track aircraft in Range, Azimuth and Elevation using a single station. The operator could Direction Find Azimuth and Elevation of a target via the Receiver system which had four aerial towers in a rhombus configuration. On each of the towers there were between 2 and 3 receiver aerials. (The original design was 3 per tower, but due to equipment shortages the stations in the Battle of Britain only had 2 per tower). The Receiver Aerials were located at the top, in the middle and towards the bottom of the tower on the three aerial system. The Signals from all of those aerials could be fed into the Receiver in various ways via switches and a device called a goniometer. The goniometer was controlled by a rotating knob on the Receiver unit, which included the display console. The goniometer control was fitted with a pointer and a angle scale. On the CRT display was a movable pointer that the operator put under the target they wanted to get the bearing and elevation of. The operator would then select the Azimuth mode (which compared the signals off the aerials in the horizonal plane) and turn the goniometer until the target they wanted to get the bearing of went to minimum deflection on the CRT. They would then read off the angle on the dial and press a button. Switch the Receiver mode to elevation which measured the signals across the aerials in the vertical plane, turn the goniometer for maximum peak signal on the CRT, read off the angle and press another button. By the time the Battle of Britain started, 21 of the Chain Home Stations were fitted with a device called the Fruit Machine. This was an Electro-Mechanical Computer which took the position of the pointer on the CRT and the Position of the goniometer when the switches were pressed and converted them into a latitude and longitude of the target on the CRT, plus its height above the sea based on the range, elevation angle and curvature of the earth. These figures were read off numbers on dials (like a gambling machine) and phoned to the Filter Room.
On a well calibrated CH Radar, with experienced operators, elevation and bearing could be quite accurate. The problem in 1940 was none of the radars had been completed to the final design standard (lack of equipment) there hadn't been time to calibrate the radars properly (lack of autogyros and ship mounted balloons to do it, bad weather and enemy actions) and a lack of experienced operators. This was why they was so many issues with incorrect bearing and heights sent to the Filter Room at Bentley Priory during the battle.
Very enjoyable and informative video.... Thanks Cap
51:37 Ryanair is everywhere
Always wondered what this place was in WT
Hi can some one in the grimreapers please help me ? I was in the process of changing my joy stick bindings and done a silly thing. I deleted all the default bindings and started to change things all went well until i came out of options and came out of the game with out saving any thing, completely forgot myself [ TWAT } NOW I CAN NOT DO ANY THING AT ALL IN DCS FLAMING CLIFFS STEAM EDITION. when i press the esc key nothing comes up at all it seems that i have deleted the the hole bloody panel with all options.How can i get it all back i've deleted the game and re installed it but the esc key brings up nothing .please please can some one help me.thank you Tony.
ps i watch a hole lot of your stuff and think its great like watching a movie.
lol how the hell u did that Tony? OK sounds like you have upset DCS. I think you need to repair it. Do you know how to do a DCS repair? If not then I have done a video on this. Search "grim reapers DCS world repair". thanks