How Germany used radio waves to guide night bombing raids in WWII | Hacker News Reader

How Germany used radio waves to guide night bombing raids in WWII

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82 pointsTheSpine14 comments

The title is terrible, but the story is interesting. Germany was using ground-based radio waves to guide aircraft, possibly including unmanned ones. It was clever, but easily jammed, especially since England had a BBC tower readily converted to a jamming system.

One wonders if they would have discovered frequency-hopping spread-spectrum, famously co-created by actress Hedy Lamarr, but her patent in 1941 was after the Germans abandoned their project. I suspect that the distances were too great for it to work well (they were trying to guide planes to specific target from transmitters in Germany and France, hundreds of miles away).

Ok, we've taken a crack at a more accurate and neutral title. If anyone has a better one, we can change it again. Thanks!

Much less clickbaity, thank you. It's a really good article.

> It's a really good article.

That is pretty much the thing we most hope to hear from users.

The systems they did use were very accurate for their time (as was the later British Oboe), despite the distances (and most of Britain is closer to occupied Europe than Eastern Germany is to Britain), so would not a spread-spectrum version be capable of similar accuracy, if the additional complications of implementation could be overcome? (and I am sure Germany's engineers were capable so doing.)

I think the countermeasures for Knickebein were deployed before the Coventry raid, but the frequency being used was not detected (by sending up 'sniffer' airplanes) that night.

According to Wikipedia, the interfering with Y-Gerät was mostly done at power levels too low to produce the 'ring-around', which was good enough to spoil the accuracy while not giving the game away, and leading the German engineers and technicians on a time-consuming and fruitless search for technical problems.

Coventry. That was not a normal raid. It is also a raid that is mired with myth. According to the legend Churchill knew all about it but 'sacrificed' Coventry as that would reveal that Enigma had been cracked.

This myth has persisted for many years and those that perpetuate it never mention that there were other sources of intelligence such as the guided radio waves, which were only turned on when the planes were on their way. There wasn't much point doing anything other than praying when the radio beams came on, it was too late to evacuate the city by then.

It is also quite hard today to appreciate what a useful place Coventry once was. It is not a particularly remarkable city, although, that said, the people there are remarkably friendly, welcoming and helpful. It also lacks urban sprawl, so although a 'big city' it does not feel that way when you enter it. Compare with nearby Birmingham where there is no green space between Birmingham proper and built up 'West Midlands'.

The myth about Churchill letting the Germans just bomb Coventry also serves to under-appreciate how important manufacturing was there. Coventry really was where it all got made, the numerous car companies that were once there all swapped over to making weapons of some sort and with no car companies there today it is hard to imagine so much came out of Coventry.

Other places the Luftwaffe helped with the town planning didn't quite have Coventry's industrial clout. Southampton, Plymouth, Bristol, Liverpool and Hull were historically ports rather than places where stuff got made although there were plenty of factories in all these cities when Britain was the 'workshop of the world'. Quite a lot was made in London too, although this is quite hard to believe given today's complete absence of smokestacks in the capital. All considered, the idea that Churchill just let Coventry go so as to not reveal Enigma is laughable.

There's lots more in The Wizard War: British Scientific Intelligence 1939-1945 by R.V. Jones.

https://www.amazon.com/Wizard-War-Scientific-Intelligence-19...

He also features a lot in the 70's BBC Series, 'The Secret War'.

A compilation of it seems to be on YouTube (for the time being). The Battle of the Beams is the first segment :

https://www.youtube.com/watch?v=GJCF-Ufapu8

Cannot recommend this book too highly. Also worth reading is anything about PMS Blackett and the birth of Operations Research, Barnes Wallis (the JP Morpugo biog is good), and Solly Zuckerman ("from apes to warlords") on the bombing accuracy issues, statistics and the 'transport plan'

its not on kindle, but Robert Buderi's book on Radar is also worth reading. from the roots up to chips and microwave physics, amazing stuff

Thanks for this comment. I recently discovered that the inventor of PCM, Alec Reeves, was also involved in the development Oboe system for guidance of bombers.

https://en.wikipedia.org/wiki/Alec_Reeves (the offsite reference pages are particularly good)

I get the sense that he was much less of a mover and shaker than either Blackett or Zuckerman. By the same token, I wonder if they have been idolized a bit (even though I had never heard of them, and their names are clearly not heard very often these days.)

Published in Britain as 'Most Secret War', in case anyone else us looking for a copy and surprised that they're all American and/or expensive...

There's an amazeballs BBC documentary on this "Secret war; the battle of the beams"

https://www.dailymotion.com/video/x123i1g

also https://en.wikipedia.org/wiki/Battle_of_the_Beams

The entire BBC series is pretty good.

It's been posted in this thread, but I'll say anyway: The British "The Secret War" documentary is absolutely fantastic and well worth watching either for the engineering or the human intelligence working around the engineers

Steve Blank has covered this issue well in his Secret History of Silicon Valley

https://steveblank.com/tag/world-war-ii/

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