Authentic BDU/U-Boat transmissions Intercepted by the Allies

[Laufen zum Ziel]

These were intercepted and deciphered in 1945

During the month of February 1941 there were transmission intercepts by the Allies from BDU and the following U-Boats: U-27, U-37, U-46, U-47, U-48, U-52, U-69, U-73, U-95, U-96, U-97, U-99, U-101, U-103, U-105, U-106, U-107, U-108, U-123, U-147 & U-552.
All of February 1941 Intercepts can be found HERE.
Credit to WWII Archives Foundation for having these on their site HERE,

This site may be suitable for sound modders to do a message mod as they are dated and time stamped.


EXAMPLE

[bigboywooly]

Nice find
Tis a pity only Feb 41 at mo but gotta start somewhere

[mookiemookie]

Very nice find!

[Sailor Steve]

Cool stuff!

[Jimbuna]

Nice one

[Puster Bill]

Originally Posted by Laufen zum Ziel

These were intercepted and deciphered in 1945

During the month of February 1941 there were transmission intercepts by the Allies from BDU and the following U-Boats: U-27, U-37, U-46, U-47, U-48, U-52, U-69, U-73, U-95, U-96, U-97, U-99, U-101, U-103, U-105, U-106, U-107, U-108, U-123, U-147 & U-552.
All of February 1941 Intercepts can be found HERE.
Credit to WWII Archives Foundation for having these on their site HERE,

This site may be suitable for sound modders to do a message mod as they are dated and time stamped.


EXAMPLE

As an ex-SIGINT weenie (I was one of the guys actually intercepting Morse transmissions, back 20 years ago), I think what you want are the raw intercepts. That's what a radio operator on the sub, or even just someone walking by the radio room, would have heard (likely by leakage from the 'cans' the operator wore).

A while back I contacted both the NSA and GCHQ to find out if they had any information on what the actual raw intercepts looked like, particularly the formatting of any preambles and postambles, and they didn't have any information. They both mentioned that the raw intercepts in most cases wouldn't have been kept, just the decrypts.

The M4 Project references some raw intercepts that were published in Cryptologia, formatted like this:
APPENDIX II (continued), TO THE COMMANDING OFFICER, H.M.S. HURRICANE'S
No. 110/S, DATED 25TH NOVEMBER, 1942.
TEXTS OF SIGNALS READ

CLXP LWRU HCEY ZTCS OPUP PZDI UQRD LWXX FACT TJMB HDVC JJMM ZRPY IKHZ
AWGL YXWT MJPQ UEFS ZBCT VRLA LZXW VXTS LFFF AUDQ FBWR RYAP SBOW JMKL
DUYU PFUQ DOWV HAHC DWAU ARSW TXCF VOYF PUFH VZFD GGPO OVGR MBPX XZCA
NKMO NFHX PCKH JZBU MXJW XKAU OD?Z UCVC XPFT CDXP LWRU VA

T.O.R.1152/19/221 (53 GROUPS).

FCLC QRKN NCZW VUSX PNYM INHZ XMQX SFWX WLKJ AHSH NMCO CCAK UQPM KCSM
HKSE INJU SBLK IOSX CKUB HMLL XCSJ USRR DVKO HULX WCCB GVLI YXEO AHXR
HKKF VDRE WEZL XOBA FGYU JQUK GRTV UKAM EURB VEKS UHHV OYHA BCJW MAKL
FKLM YFVN RIZR VVRT KOFD ANJM OLBG FFLE OPRG TFLV RHOW OPBE KVWM UQFM
PWPA RMFH AGKX IIBG FCLC QRKM VA


T.O.R.1840/19Z (62 GROUPS).

YKRB MGVA TMKF NWZX FFII YXUT IHWM DHXI FZEQ VKDV MQSW BQND YOZF TIWM
JHXH YRPA CZUG RREM VPAN WXGT KTHN RLVH KZPG MNMV SECV CKHO INPL HHPV
PXKM BHOK CCPD PEVX VVHO ZZQB IYIE OUSE ZNHJ KWHY DAGT XDJD JKJP KCSD
SUZT QCXJ DVLP AMGQ KKSH PHVK SVPC BUWZ FIZP FUUP YKRB MGVA VA

T.O.R.0321/21Z (54 GROUPS).

0557Z Corrections to above W 51 FIZP W 54 MGVA.

About the only formatting I can find is the common "VA" at the end of the messages, which
is probably a corruption of "SK", or "End of Schedule". They have almost the same pattern
in Morse:

VA ...- .-
SK ... -.-

I also note that in every case, the first and second group are repeated at the end of the message. This suggests to me that they are some kind of indicator, and the actual message doesn't start until the third group, although I could be talking out my sphinctoral orifice.

If anyone would like, I can hand-key some Morse formatted similar to that to make a sound file.
Someone else would have to convert it to .ogg though.

*Exceptions are first message with CDXP/CLXP and the second message with QRKM/QRKN. Both would have been relatively common Morse garbles.

[Puster Bill]

Just by way of explanation for the uninitiated, when messages are passed in Morse they are often preceded by a "preamble". Often, this contains things like a message serial number, a date and/or time group(s), the number of groups in the message, and sometimes other administrivia.

Sometimes that information is actually encoded in the message, though. The danger in doing that is that you give the enemy a stereotyped beginning which can help him break your codes/ciphers. Sending the information in the clear helps prevent that.

Here is a notional example of a preamble for a message:

NR 123 GR 8 0221 0904 BT
THISI SSUPP OSEDT OBEAN ENCRY PTEDM ESSAG EXXX
AR

NR 123 is the serial number, ie., this is the 123rd message from this entity
GR 8 is the number of groups, 8.
0221 is the date the message was sent, February 21st
0904 is the time the message was sent, 09:04
BT is a 'prosign' that means "Break Text", and it separates the preamble from the actual message.

After the 8 groups are sent, the operator sends "AR" which is a Morse prosign that means "End of Message".

I have yet to find evidence that the U-bootwaffe radio operators used preambles, or indeed if they even used callsigns to call up the other side. To the best of my knowledge (which is admittedly scant and circumstantial), it seems as if Ubootwaffe communications were sent "blind" on fixed frequencies with no calling involved. In other words, if BdU wanted to contact KL Schmidt on U-127, they would transmit just the encrypted part of the message, depending on the radio operator on U-127 to be alert and copy it (and all the other boats at sea would copy it also, unless they were submerged to deep to receive it). The radio operator on all the boats would decrypt the message, but for most it wouldn't apply.

Likewise, the operator on the boat would send a message "blind" to BdU, but because BdU had extensive receiver facilities and never submerged obviously, they were more likely to receive messages. BdU would acknowledge the message by repeating it with a serial number attached.

The frequencies involved would have been picked according to what worked best at that time of day for "DX" communications, higher frequencies for the day and lower ones at night. BdU would also transmit using their VLF transmitter, which could be received underwater and at great distances. The HF frequencies would be relative: boats in the North Sea would use generally lower frequencies than boats in areas farther away, because otherwise the station they intended to contact would be within the shadow of the "skip zone" and wouldn't be heard. Different operational areas would have different sets of frequencies.

Probably the best way to simulate the sound of a message being received would be to send a couple sets of V's (often used by operators to "warm up" and make sure the transmitter is operating properly), followed by some 4 letter code groups, and ended with an "AR" and perhaps an "SK", so it would look something like this:

VVV VVV
INDI CATR IFYO CANR EADT HISY OURT WODA MNED CLOS EXXX INDI CATR
SK

VVV VVV is the operator sending some V's to warm up, check his transmitter, and to alert the receiving operators that something is going to be sent.

INDI and CATR are the "Indicator" groups, sent at the beginning of the message and repeated at the end, with the actual message in between.

The SK or VA at the end is the prosign that signals the end of the transmission. I prefer the "SK" usage because that's what I'm used to, but in practice it makes no difference whether you copy it as SK or VA, the two characters are "run together" to make one big prosign, so it's a chose your preference kind of thing.

If you wanted to be really funny, you could make an 'Easter Egg' in the form of a message encrypted in Naval Enigma, formatted like an actual message, and record it using fast hand-keyed Morse. Might be an interesting exercise.

[Thomen]

http://www.u-boot-zentrale.de/eng/En...tandalone.html

He got an Enigma Emulator applet and an original coded message as example on his page.

[Thomen]

Originally Posted by Puster Bill

Just by way of explanation for the uninitiated, when messages are passed in Morse they are often preceded by a "preamble". Often, this contains things like a message serial number, a date and/or time group(s), the number of groups in the message, and sometimes other administrivia.

Sometimes that information is actually encoded in the message, though. The danger in doing that is that you give the enemy a stereotyped beginning which can help him break your codes/ciphers. Sending the information in the clear helps prevent that.

Here is a notional example of a preamble for a message:

NR 123 GR 8 0221 0904 BT
THISI SSUPP OSEDT OBEAN ENCRY PTEDM ESSAG EXXX
AR

NR 123 is the serial number, ie., this is the 123rd message from this entity
GR 8 is the number of groups, 8.
0221 is the date the message was sent, February 21st
0904 is the time the message was sent, 09:04
BT is a 'prosign' that means "Break Text", and it separates the preamble from the actual message.

After the 8 groups are sent, the operator sends "AR" which is a Morse prosign that means "End of Message".

I have yet to find evidence that the U-bootwaffe radio operators used preambles, or indeed if they even used callsigns to call up the other side. To the best of my knowledge (which is admittedly scant and circumstantial), it seems as if Ubootwaffe communications were sent "blind" on fixed frequencies with no calling involved. In other words, if BdU wanted to contact KL Schmidt on U-127, they would transmit just the encrypted part of the message, depending on the radio operator on U-127 to be alert and copy it (and all the other boats at sea would copy it also, unless they were submerged to deep to receive it). The radio operator on all the boats would decrypt the message, but for most it wouldn't apply.

Likewise, the operator on the boat would send a message "blind" to BdU, but because BdU had extensive receiver facilities and never submerged obviously, they were more likely to receive messages. BdU would acknowledge the message by repeating it with a serial number attached.

The frequencies involved would have been picked according to what worked best at that time of day for "DX" communications, higher frequencies for the day and lower ones at night. BdU would also transmit using their VLF transmitter, which could be received underwater and at great distances. The HF frequencies would be relative: boats in the North Sea would use generally lower frequencies than boats in areas farther away, because otherwise the station they intended to contact would be within the shadow of the "skip zone" and wouldn't be heard. Different operational areas would have different sets of frequencies.

Probably the best way to simulate the sound of a message being received would be to send a couple sets of V's (often used by operators to "warm up" and make sure the transmitter is operating properly), followed by some 4 letter code groups, and ended with an "AR" and perhaps an "SK", so it would look something like this:

VVV VVV
INDI CATR IFYO CANR EADT HISY OURT WODA MNED CLOS EXXX INDI CATR
SK

VVV VVV is the operator sending some V's to warm up, check his transmitter, and to alert the receiving operators that something is going to be sent.

INDI and CATR are the "Indicator" groups, sent at the beginning of the message and repeated at the end, with the actual message in between.

The SK or VA at the end is the prosign that signals the end of the transmission. I prefer the "SK" usage because that's what I'm used to, but in practice it makes no difference whether you copy it as SK or VA, the two characters are "run together" to make one big prosign, so it's a chose your preference kind of thing.

If you wanted to be really funny, you could make an 'Easter Egg' in the form of a message encrypted in Naval Enigma, formatted like an actual message, and record it using fast hand-keyed Morse. Might be an interesting exercise.

You can also try and contact the National Cryptologic Museum at Fort Mead.
http://www.nsa.gov/about/cryptologic...um/index.shtml

They have some Enigmas on display and visitors are allowed to play around with them. They might be able to give some more detailed information on the formating and stuff. When I was there last year, I picked up some booklets about the Enigma, but I do not remember if they tell you much about the actual formating.

[Puster Bill]

Originally Posted by Thomen

You can also try and contact the National Cryptologic Museum at Fort Mead.
http://www.nsa.gov/about/cryptologic...um/index.shtml

They have some Enigmas on display and visitors are allowed to play around with them. They might be able to give some more detailed information on the formating and stuff. When I was there last year, I picked up some booklets about the Enigma, but I do not remember if they tell you much about the actual formating.

That's who I contacted at NSA. This is the response I got:

Dear Bill,

The Center for Cryptologic History does not have any raw intercepts of U-Boat messages in its possession. Nor does it have any guide to U-Boat message formats. There is a good possibility that such material resides at the National Archives in College Park, Maryland. There are two records groups where such material might be found: RG 457, The Records of the National Security Agency/Central Security Service, Entry 9032, "Historical Cryptographic Collection." In this collection there are about 12-15 boxes of material dealing with the U-Boat problem. Anothee place may be in RG 38, Records of the Chief of Naval Operations, Commander Naval Security Group. There are several collections within this record group, notably the mistitled "Translations", Entry 1040, which has severl aboxes of material on the U-Boats, some of which are translations, but many boxes hold other material related to the U-Boat problem.

Sorry, we could not be of more help. It might be helpful to know that the British retained the "lead" on this problem, and while the processing of U-Boat intercepts was done both in the US and the UK, primary responsibility for intercept belonged with the British. Original intercept rarely was kept by the Americans, except for training purposes. But with the end of the war, there was little incentive to retain such material. As for the Britsh, what originals they retained is unknown.

Bob Hanyok
Historian

I didn't and still don't have the time or money to go waltzing down to Maryland to search through the National Archives, though. If someone in the area has the time, I would personally appreciate it if they could check.


I did contact Bletchley Park to see what they had, and I got an acknowledgement of the e-mail from the reception desk saying they would forward the request to the archives, and nothing afterwards. I never got a reply from GCHQ at all.

[Thomen]

Originally Posted by Puster Bill

That's who I contacted at NSA. This is the response I got:

Dear Bill,

The Center for Cryptologic History does not have any raw intercepts of U-Boat messages in its possession. Nor does it have any guide to U-Boat message formats. There is a good possibility that such material resides at the National Archives in College Park, Maryland. There are two records groups where such material might be found: RG 457, The Records of the National Security Agency/Central Security Service, Entry 9032, "Historical Cryptographic Collection." In this collection there are about 12-15 boxes of material dealing with the U-Boat problem. Anothee place may be in RG 38, Records of the Chief of Naval Operations, Commander Naval Security Group. There are several collections within this record group, notably the mistitled "Translations", Entry 1040, which has severl aboxes of material on the U-Boats, some of which are translations, but many boxes hold other material related to the U-Boat problem.

Sorry, we could not be of more help. It might be helpful to know that the British retained the "lead" on this problem, and while the processing of U-Boat intercepts was done both in the US and the UK, primary responsibility for intercept belonged with the British. Original intercept rarely was kept by the Americans, except for training purposes. But with the end of the war, there was little incentive to retain such material. As for the Britsh, what originals they retained is unknown.

Bob Hanyok
Historian

I didn't and still don't have the time or money to go waltzing down to Maryland to search through the National Archives, though. If someone in the area has the time, I would personally appreciate it if they could check.

I might swing by there at some point depending the difference in the cost between the US National Archives and the Federal German Archives for a complete u-boot ships journal.

I also found this:
http://users.telenet.be/d.rijmenants/en/kurzsignale.htm
He got some of the code books that were in use, too.

[Puster Bill]

OK, it appears that:

A. Ubootwaffe transmission *DID* have a preamble, that was formatted like this:

BDU 1540/8/107 24

"BDU" is the recipient, 1540 is the time, 8 is the day of the month, and 107 signifies that this is the 107th message from this sender. 24 is the number of groups.

B. I was correct in assuming that the first and second groups are indicators. They are in fact the wheel settings encrypted by the use of a "bigram table" to disguise the settings.

You can find this at http://users.telenet.be/d.rijmenants/en/enigmaproc.htm

If you want to hear what it sounds like in Morse, I posted a Youtube video of me sending it here:

And this is what I sent (with a couple of sloppy characters in there):

BDU 1540/8/107 24 BT
ADWL CFNP DERH RFRS OQRV DTYH QWBV HILS CXHR OPOD
GTQL DDHI KFTG EDZS WXQS EDFR HGYG EDZZ UYQV DTYY
EDGH KIRM ADWL CFNP
AR K


I keyed the side-tone on my ham radio transceiver with my straight key, and the
radio was tuned to 7041 kilocycles, but no actual transmission went over the air.

[Laufen zum Ziel]

Lots of great Info from everyone.

[Jimbuna]

Originally Posted by Thomen

http://www.u-boot-zentrale.de/eng/En...tandalone.html

He got an Enigma Emulator applet and an original coded message as example on his page.

First time I've seen that site...cheers

[Thomen]

Originally Posted by jimbuna

First time I've seen that site...cheers

Here is more about that particular message. Boat, Captain and fate.