Wednesday, September 11, 2019

RDF

Scanning Chain Home Installations - The Last Zeppelin Raid 1939 - mfp > .


Radar is an object-detection system that uses radio waves to determine the range, angle, or velocity of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna (often the same antenna is used for transmitting and receiving) and a receiver and processor to determine properties of the object(s). Radio waves (pulsed or continuous) from the transmitter reflect off the object and return to the receiver, giving information about the object's location and speed.

Radar was developed secretly for military use by several nations in the period before and during World War II. The term RADAR was coined in 1940 by the United States Navy as an acronym for RAdio Detection And Ranging. The term radar has since entered English and other languages as a common noun, losing all capitalization.

The modern uses of radar are highly diverse, including air and terrestrial traffic control, radar astronomy, air-defence systems, antimissile systems, marine radars to locate landmarks and other ships, aircraft anticollision systems, ocean surveillance systems, outer space surveillance and rendezvous systems, meteorological precipitation monitoring, altimetry and flight control systems, guided missile target locating systems, ground-penetrating radar for geological observations, and range-controlled radar for public health surveillance. High tech radar systems are associated with digital signal processing, machine learning and are capable of extracting useful information from very high noise levels.

Other systems similar to radar make use of other parts of the electromagnetic spectrum. One example is "lidar", which uses ultraviolet, visible, or near infrared light from lasers rather than radio waves.

http://www.bbc.co.uk/history/topics/radar

https://www.youtube.com/watch?v=BSajdavR6Yw >


RADAR
Naval (ASV) and airborne (AI) RADAR
https://youtu.be/uTE-jHVIKJU?t=26m39s .


RADAR - Kammhuber Line - German night air defense system
The Kammhuber Line was the Allied name given to the German night air defense system established in July 1940 by Colonel Josef Kammhuber. It consisted of a series of control sectors equipped with radars and searchlights and an associated night fighter. Each sector would direct the night fighter into visual range with target bombers.
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When Germany organised its air defences into the Kammhuber Line, it was realised by the British (Bomber Command's Operational Research Section (BC-ORS)) that if the RAF bombers were to fly in a bomber stream they could overwhelm the night fighters who flew in individual cells directed to their targets by ground controllers. It was then a matter of calculating the statistical loss from collisions against the statistical loss from night fighters to calculate how close the bombers should fly to minimise RAF losses.

British intelligence soon discovered the nature of the Kammhuber Line and started studying ways to defeat it. At the time RAF Bomber Command sent in their planes one at a time to force the defenses to be spread as far apart as possible, meaning that any one aircraft had to deal with little concentrated flak. This also meant the Himmelbett centres were only dealing with perhaps one or two planes at a time, making their job much easier.

At the urging of R.V. Jones, Bomber Command reorganized their attacks into streams of bombers – the so-called Bomber stream, carefully positioned so the stream flew down the middle of a single cell. Data provided to the British scientists allowed them to calculate that the bomber stream would overwhelm the six potential interceptions per hour that the German "Tame Boar" (Zahme Sau) night fighters could manage in a Himmelbett zone. It was then a matter of calculating the statistical loss from collisions against the statistical loss from night fighters to calculate how close the bombers should fly to minimise RAF losses. The introduction of Gee radio navigation in 1942 allowed the RAF bombers to fly by a common route and at the same speed to and from the target, each aircraft being allotted a height band and a time slot in a bomber stream to minimize the risk of collision. The first use of the bomber stream was the first 1,000 bomber raid against Cologne on the night of 30/31 May 1942. This tactic was extremely effective, leading to fighting between Kammhuber and Erhard Milch, his boss.

Although the success rate of the Line dropped, the network of radars and plotting stations continued to prove their worth. Now when a raid started, night fighters from any base within range were directed into the stream, where it was hoped they would be able to find aircraft with their radar. At the same time a massive building program started to add hundreds of Würzburgs to the system, although the infrastructure needed was extensive. The boxes were initially the radius of the Würzburg radars, about 22 miles, but more powerful radar later on made the boxes up to 100 miles across. Eventually, the line of boxes was several deep, especially around larger towns and the Ruhr valley. Once again the system started to score increasing successes against the British raids.

The British were ready for this development, and as soon as the rates started to improve – for the Germans – they introduced "Window". Dropping strips of foil from a number of "lead" bombers, the German radar operators saw what appeared to be a stream entering their box, each packet of chaff appearing to be a bomber on their displays. Night fighters were then sent to attack this stream, only to find empty space. Just as the fighters reached the false stream, the "real" stream appeared hundreds of miles away, too far to be attacked. The first time this was used was during Operation Gomorrah (a week-long bombing campaign against Hamburg) and proved spectacularly effective. The German radar operators eventually learned to spot the lead bombers at the edge of the windowing, making it less effective. The British had held back from introducing Window for over a year lest the technique be adopted by the Germans and used against British cities.

A more sophisticated method for blinding the German radar was "Mandrel", a jamming signal broadcast from aircraft accompanying the bomber stream or later certain bombers themselves. This progressed into jamming techniques against individual German radar types and spoofing radars to see bomber streams that weren't there. The British also attacked the communications between ground stations and fighters, with Operation Corona, broadcasting false directions in authentic accents over the radio.

One other element was long-range nightfighters operating against the German nightfighters, using a system called "Serrate" to home in on the German nightfighter radar signals. At least three squadrons equipped with Bristol Beaufighter and de Havilland Mosquito were part of No. 100 Group RAF supporting Bomber Command with electronic countermeasures.

https://en.wikipedia.org/wiki/Operations_research
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The Line was very effective at first, but was soon rendered useless by a simple change in tactics. The RAF directed all of its bombers to fly in a single stream, overwhelming the sectors, who could only intercept a single aircraft at a time. This led to a dramatic drop in interception rates compared to the raid size. The Line was eventually turned into a radar network, and the night fighters improved with their own radar sets to allow them to hunt on their own.
https://en.wikipedia.org/wiki/Kammhuber_Line

RDF – Plane Safety ‘38

Battle Stations - Radar - Documentary + Rare Bonus Footage
https://www.youtube.com/watch?v=NRvcLNLe3VU
Under The Radar - Radar Technological Evolution
https://www.youtube.com/watch?v=BSajdavR6Yw

Chain Home:

Early Radar Memories .
http://spitfiresite.com/2010/04/early-radar-memories.html
Stories of the Battle of Britain 1940 – Chain Home .
http://spitfiresite.com/2010/08/stories-of-the-battle-of-britain-1940-chain-home.html
“The Spies Who Lost the Battle of Britain” .
http://spitfiresite.com/2010/11/the-spies-who-lost-the-battle-of-britain.html
Aboukir’s High-Altitude Spitfire .
http://spitfiresite.com/2010/04/aboukirs-high-altitude-spitfire.html
http://spitfiresite.com/2010/04/deflating-british-radar-myths-of-world-war-ii.html

Filter Room
http://www.telegraph.co.uk/history/battle-of-britain/11865303/The-Battle-of-Britain-as-it-happened-on-September-15-1940-live.html .

Boffins Beat Belligerents >> .
RAF Uxbridge - WW2 command centre > .

RDF – Plane Safety ‘38 > .

RDF - New Forest
New Forest, WW2 ..

Early Radar Memories
http://spitfiresite.com/2010/04/early-radar-memories.html
Stories of the Battle of Britain 1940 – Chain Home
http://spitfiresite.com/2010/08/stories-of-the-battle-of-britain-1940-chain-home.html
“The Spies Who Lost the Battle of Britain”
http://spitfiresite.com/2010/11/the-spies-who-lost-the-battle-of-britain.html
Aboukir’s High-Altitude Spitfire
http://spitfiresite.com/2010/04/aboukirs-high-altitude-spitfire.html


http://spitfiresite.com/2010/04/deflating-british-radar-myths-of-world-war-ii.html




RAF Bawdsey > .

1940s: Radar, RAF High Speed Launch (HSL), AFS, 1941 Jowett pump, Austin 12 taxi, Austin K Fire Truck, WLA & David Brown VAK1 tractor, cavity magnetron & H2S, Daimler Scout Car (Dingo), Bren Gun, gas turbine = Whittle jet engine, Gloster Pioneer & Meteor, ejector seat, Aston Martin DB1 & DB2 & DBR1

https://www.youtube.com/user/EnginePorn/playlists?view=1&shelf_id=0&sort=dd .

Of zoos and fire-fighting, today and in wartime
https://web.archive.org/web/20110902160428/http://worldwarzoogardener1939.wordpress.com/2011/03/22/of-zoos-and-fire-fighting-today-and-in-wartime/

Britain's greatest machines - 1940s > .

https://www.youtube.com/watch?v=eWSMJFeBfj4&list=PLrWZd-gHTah5CuJVlQgNFmk5jeh0-7mNx

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