How the Germans failed to Detect Chain Home Radar

[watchmaker]

I just watched "Battle for Britain: Radar".  The Germans probed the installations with a Zeppelin pre war but failed to identify the radar even though they in fact detected it.

SPOILER ALERT

So the deal was that all they detected all the way up the coast was a 25 Hz pulse that never changed.  They concluded the UK's grid was very leaky.  But in fact, Watkins-Watt chose to use the grid's frequency for his pulse generator.

This also had the advantage of automatically synchronizing all 13 stations.

The Germans were looking for a much higher frequency signal and ultimately dismissed what they detected.

Some very good photos of the installations and discussion of the issues.  It actually offers a very plausible explanation for Chamberlain's acquiescence.

[ebastler]

[...] all they detected all the way up the coast was a 25 Hz pulse
[...] The Germans were looking for a much higher frequency signal and ultimately dismissed what they detected.

They were not looking for a higher pulse rate, but a higher carrier frequency (than the ~25 MHz and 200 MHz used by the British), right?

[Stray Electron]

   What surprises me is that the Germans apparently failed to realize the significance of the Bruneval Raid in early 1942 in which the British raided a German RADAR site in France and stole parts of it and took them back to Britain for analysis. 

   The Germans completely underestimated the British time and time again at many critical points and it ultimately cost them the war.

[watchmaker]

According to my understanding, the Chain Home was pulsed at 25 Hz (cps) based off the 50Hz UK grid.

[ebastler]

   The Germans completely underestimated the British time and time again at many critical points and it ultimately cost them the war.

I generally agree. But in the particular case of radar technology, it seems that the Germans overestimated the British -- reckoning that they could not be using the rather dated 12 m wavelength technology for radar, and hence assuming it was something else.

[themadhippy]

 radar had nought to do with our sucsess ,it was down to our military eating plenty of carrots.

[DenzilPenberthy]

If you are interested in this topic I can 1000% recommend the book 'Most Secret War' by R.V. Jones.

I saw it on the shelf at a relative's house and picked it up out of idle interest and was absolutely hooked.

R.V. Jones was the director of Scientific Intelligence during the war and oversaw (and was involved very practically in) all of this stuff. The reverse engineering of the German equipment, the Bruneval raid, and the development of British systems and countermeasures, the 'Battle of the Beams', etc etc.  The book lays it all out in fantastic detail and is very well written.

https://www.waterstones.com/book/most-secret-war/r-v-jones/9780141042824

[coppice]

radar had nought to do with our sucsess ,it was down to our military eating plenty of carrots.

That only helped with line of sight detection. Longer distances still required electronics.

[brucehoult]

radar had nought to do with our sucsess ,it was down to our military eating plenty of carrots.

The most successful misdirection ever. Not only my grandparents (in New Zealand) believed that carrots improved night vision, but also youngish ex USSR people who I meet today.

My grandmother's brother, Mervyn Legg (4 Jan 1917 - 7 Nov 1993) served in the RNZAF in WW2 as a RADAR technician at RAF Ventnor on the Isle of Wight. After the war he owned a radio and TV sales and repair shop in Pukekohe NZ in which I spent happy hours in some school holidays in the late 70s "helping" him with fault diagnosis and repair work, and building a few little things of my own from spare components.

[brucehoult]

radar had nought to do with our sucsess ,it was down to our military eating plenty of carrots.

That only helped with line of sight detection. Longer distances still required electronics.

No, the carrots story was just a complete fabrication.

[coppice]

   The Germans completely underestimated the British time and time again at many critical points and it ultimately cost them the war.

I generally agree. But in the particular case of radar technology, it seems that the Germans overestimated the British -- reckoning that they could not be using the rather dated 12 m wavelength technology for radar, and hence assuming it was something else.

There was nothing really dated about using 12m. The home chain worked well for its time. If you see powerful radio pulses, and you don't see that as either a detector or a navigation system there's something wrong with you. This story about the Germans makes no sense.

[coppice]

radar had nought to do with our sucsess ,it was down to our military eating plenty of carrots.

That only helped with line of sight detection. Longer distances still required electronics.

No, the carrots story was just a complete fabrication.

Really? I'm shocked to hear that.

[nali]

If you are interested in this topic I can 1000% recommend the book 'Most Secret War' by R.V. Jones.

I saw it on the shelf at a relative's house and picked it up out of idle interest and was absolutely hooked.

R.V. Jones was the director of Scientific Intelligence during the war and oversaw (and was involved very practically in) all of this stuff. The reverse engineering of the German equipment, the Bruneval raid, and the development of British systems and countermeasures, the 'Battle of the Beams', etc etc.  The book lays it all out in fantastic detail and is very well written.

https://www.waterstones.com/book/most-secret-war/r-v-jones/9780141042824

I can second that... I read it years ago.

IIRC Jones was a protagonist for using Infra Red for aircraft detection, but lost out to Radar development, and the rest is history so they say.

[Xena E]

   The Germans completely underestimated the British time and time again at many critical points and it ultimately cost them the war.

I generally agree. But in the particular case of radar technology, it seems that the Germans overestimated the British -- reckoning that they could not be using the rather dated 12 m wavelength technology for radar, and hence assuming it was something else.

There was nothing really dated about using 12m. The home chain worked well for its time. If you see powerful radio pulses, and you don't see that as either a detector or a navigation system there's something wrong with you. This story about the Germans makes no sense.

German technologies at the time were set up for the offensive, they had radar, but it was initially utilised for guidance purposes.
Britain's chain home system did have the advantage of range.

The Germans saw no great need for it in a defensive role having the knowledge of Britain's lack of long range bomber capabilities in the later 1930s.

The mistake the Germans made was the London blitz. Had they maintained a systematic offensive against solely military targets their early advantage and goal of overrunning Britain by the end of 1942 would have been achievable.

One of the saddest mistakes by order of Winston Churchill was the assumption that the Germans didn't know Britain's had radar, so he didn't want to give them any suspicion that there was any kind of early warning. He refused the RAF permission to engage bombers that attacked Coventry until the beginning of the strike , a decision killing countless more civilians and destroying a great deal of essential industry for no reason.

What a hero.

[watchmaker]

   The Germans completely underestimated the British time and time again at many critical points and it ultimately cost them the war.

I generally agree. But in the particular case of radar technology, it seems that the Germans overestimated the British -- reckoning that they could not be using the rather dated 12 m wavelength technology for radar, and hence assuming it was something else.

There was nothing really dated about using 12m. The home chain worked well for its time. If you see powerful radio pulses, and you don't see that as either a detector or a navigation system there's something wrong with you. This story about the Germans makes no sense.

German technologies at the time were set up for the offensive, they had radar, but it was initially utilised for guidance purposes.
Britain's chain home system did have the advantage of range.

The Germans saw no great need for it in a defensive role having the knowledge of Britain's lack of long range bomber capabilities in the later 1930s.

The mistake the Germans made was the London blitz. Had they maintained a systematic offensive against solely military targets their early advantage and goal of overrunning Britain by the end of 1942 would have been achievable.

One of the saddest mistakes by order of Winston Churchill was the assumption that the Germans didn't know Britain's had radar, so he didn't want to give them any suspicion that there was any kind of early warning. He refused the RAF permission to engage bombers that attacked Coventry until the beginning of the strike , a decision killing countless more civilians and destroying a great deal of essential industry for no reason.

What a hero.

Actually, according to the documentary, the Air Ministry ASSUMED the Germans knew about the Radar since pre war.  The 300 ft towers were easily seen from France. Especially after the Zeppelin reconnaissance and then the loss of some mobile equipment at Dunkirk.  As I recall, Coventry was allowed to be attacked, but for some other reason I forget.

[themadhippy]

they had radar, but it was initially utilised for guidance purposes.

until we bent it

[Xena E]

As I recall, Coventry was allowed to be attacked, but for some other reason I forget.

There were several reasons given, possibly all have some credence, but the main ones were the radar and the other was that codebreakers had intercepted a message about a major bombing, "midnight sonata raid" in retaliation for the bombing of Berlin. Winnie was against revealing either to be the reason for countermeasures.

[coppice]

As I recall, Coventry was allowed to be attacked, but for some other reason I forget.

There were several reasons given, possibly all have some credence, but the main ones were the radar and the other was that codebreakers had intercepted a message about a major bombing, "midnight sonata raid" in retaliation for the bombing of Berlin. Winnie was against revealing either to be the reason for countermeasures.

Let's be realistic. In a war the mostly likely explanation is that it was a complete cock up.

[Xena E]

As I recall, Coventry was allowed to be attacked, but for some other reason I forget.

There were several reasons given, possibly all have some credence, but the main ones were the radar and the other was that codebreakers had intercepted a message about a major bombing, "midnight sonata raid" in retaliation for the bombing of Berlin. Winnie was against revealing either to be the reason for countermeasures.

Let's be realistic. In a war the mostly likely explanation is that it was a complete cock up.

 


As likely as no one dared tell the powers that be in the war cabinet that Germans weren't stupid people who could be convinced the towers were for early TV, and all that carrot crap, for being able to spot their planes.

X

[iMo]

radar had nought to do with our sucsess ,it was down to our military eating plenty of carrots.

Another sources say:

..it was not your military, but group of US gunners located east of London helping with shooting down V1 flying bombs. When nearby stationed UK gunners asked the US gunners (while drinking in the local pub) why their efficiency in shooting down the V1s is much higher than theirs, they answered because they eat a lot of carrots..
In reality the US gunners were using proximity fuses already (and a top secret info at that time)..
 

[jonovid]

the misguided assumption by the Germans at the time, that the British was incapable of having a working radar system. when they in fact did.
today history repeats itself in regards to current 2024 military conflicts.

[Stray Electron]

radar had nought to do with our sucsess ,it was down to our military eating plenty of carrots.

Another sources say:

..it was not your military, but group of US gunners located east of London helping with shooting down V1 flying bombs. When nearby stationed UK gunners asked the US gunners (while drinking in the local pub) why their efficiency in shooting down the V1s is much higher than theirs, they answered because they eat a lot of carrots..
In reality the US gunners were using proximity fuses already (and a top secret info at that time)..
 

  Well eating carrots was a plausible reason for the American's accuracy. So plausible that here we are 80 years later and mothers are still telling their kids that eating carrots will help improve their vision.

[coppice]

the misguided assumption by the Germans at the time, that the British was incapable of having a working radar system. when they in fact did.
today history repeats itself in regards to current 2024 military conflicts. one might say the boot is on the other foot.
 its astonishing to see how some misguided technological assumptions are still been made.
inspite of all the information that is now freely available to anyone who cares to look for it.
the misguided assumption that A known nuclear superpower today, is somehow technologically challenged and therefore incapable of particular technological advancements. even called a giant gasoline station by some military commentators.

Its hard to know what is real thinking and what is just something presented to the public. In the past I was interviewed, along with colleagues, by people from the security services, about the levels of performance we were achieving, and might expect to achieve over the next few years. We were surprised how pragmatic those guys were in trying to assess where the opposition might be compared to us. There was obviously some hand waving, due to a lack of detailed knowledge, but they didn't try to big up the other side, or put them down. We found them quite balanced.

[coppice]

radar had nought to do with our sucsess ,it was down to our military eating plenty of carrots.

Another sources say:

..it was not your military, but group of US gunners located east of London helping with shooting down V1 flying bombs. When nearby stationed UK gunners asked the US gunners (while drinking in the local pub) why their efficiency in shooting down the V1s is much higher than theirs, they answered because they eat a lot of carrots..
In reality the US gunners were using proximity fuses already (and a top secret info at that time)..
 

Another story is the government nutrition people, trying to work out how to keep the country adequately fed when cut off from farms in the empire, used the carrot thing as a way to increase consumption of root vegetables that grow well in the UK.

[IanB]

Another story is that carrots are, in fact, good for eye health. Carrots are a good source of beta-carotene, and beta-carotene is known to be beneficial in many ways, including supporting eye health, and reducing the risk of certain eye problems.