Questionnaire
  
 
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for
  
 
Reporting on Communications
  
 
( Order " Marco Polo " )
  
     
     
     
     
 
a) Testing of the aforementioned communications arrangements.  Issues.
   
b) Up to which area could the transmitter of the U-boat Circuits be heard?  Short and Very Long wavelengths.  Best Circuit or wavelengths.
   
c) Difficulty in picking up communications from radio circuit "Bruno"
   
d) Difficulty with sending communications from the boat to the homeland.
   
e) Experience with traffic from Choshi Radio and reception from Tokyo Radio.
   
f) Suggestions for the U-boat Communications Service in similar operations aa) up to Penang bb) up to port of destination.
 
     
     
     
     
     
     
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C  o  m  m  u  n  i  c  a  t  i  o  n  s    R  e  p  o  r  t  .
  
 
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Communications Order "Marco Polo"
  
     
     
 
To a) Up to Penang faultless communications with the homeland - boat and vice versa.  After Penang gap-less reception of all Serial Nos. was no longer possible.  Sending side gave great difficulties.
   
To b) See Signal Strength list.
   
To c) Up to Penang good reception on Wavelength 8 and 12.  Directional transmitter for the Indian Ocean heard with Volume 4/5.  Directional transmitter for the North Atlantic was often heard by day with Volume 3.  From Penang only the directional transmitter for the North Atlantic was still heard, because the directional transmitter for the Indian Ocean was continually interfered with by a strong radio transmitter.  From 29.7.43 starting from naval square MX to the objective harbor on radio circuit "Bruno" only still more difficult reception in the period from 18.00 to 01.00 hours DGZ.  All radio messages could no longer be picked up.
   
To d) In the Indian Ocean there were no difficulties sending Radio Messages.  In the South China Sea sent Radio Message on 36 meters (1142/26) was not heard.  On the other hand, in the Malacca Strait on America I, Wavelength "cd" sent Radio Message (1212/24/257) was acknowledged with Volume 2/3 and "r" was acknowledged.  No confirmation followed on the base circuit.  The Command accepts that the Radio Message encrypted with Ägier was treated as not solvable on the U-boat circuit.
   
To e) On 29.7.43 Choshi Radio was called from the boat in accordance with Communications Order "Marco Polo", Enclosure II, (Kirschblüte [Cherry Blossom]) at 11.40 hours DGZ as follows:  JJU de IeD qtc k, (JJU runs cq strip).  Boat called further:  11.55 hours JJU sent bk and answered with qrk k. Radio Message was sent up to the third group.  JJU sent bk qrm as.  Boat waited.  12.10 hours JJU called qrk ud k.  Boat sent qrk qsa 3 ok hr 1 etc. (Radio Message was sent).  Afterwards qsl requested.  JJU no longer answered.  Continued to call approximately every 10 minutes.  After a while sent JJU ud ud qrk k.  Boat called further and requested once again qsl ud.  JJU no longer answered.  JJU called in certain intervals still twice qrk ud k.  Then let cq strip run and no longer answered.  On 30.7. 03.30 hours DGZ the boat called again:  JJU de I4D qtc k.  JJU then sent qrz ud and then silence.  Broke traffic off.  From 30.7. 07.10 hours DGZ boat called:  JJU de I4D qtc k.  07.30 after cq strip he boat called again.  JJU sent qrk qsa 3 k.  Boat sent Radio Message off.  Was not completely understood by JJU and requested um rpt qsz k.  After sending once again JJU repeated our Radio Message with a few errors, which however were immediately corrected.  At 08.33 hours traffic was finally ended.
 
     
     
     
 
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  So communications with Choshi Radio was very difficult.  From Naval Attaché Tokyo receipt of the Radio Message were not confirmed.  Radio Message reception from one sided service of Tokyo Radio was always good and assured.
   
To f) The Command suggests that directional transmitter DGM for the Indian Ocean be used at certain Program Times also for the "Afrika" U-boat Circuit.  The suitable Very Low Frequency transmitter for Afrika was "Goliath", because the control transmitter 15.5 kHz was even heard by day still with Volume 4/5, while sometimes the other wavelengths were no longer heard.
  The transition to radio circuit "Bruno" only needs to take place from 80°E.  Since from Penang it is no longer possible to pick up all Radio Messages on the "Bruno" Circuit without gaps, it is proposed that the Tokyo Radio one-side service broadcast the messages intended for the boat during its Program Times.  To check whether all Radio Message broadcast by the one-way service Tokyo Radio are picked up, they must be numbered consecutively. Since all other Radio Messages originating from Naval Attaché Tokyo are encrypted by other encryption means, all Radio Messages encrypted with Ägier [Norse god who personifies the sea] must be identified externally, otherwise the boat has no key check.  At the instigation of the boat, the following solution was found between Penang and the objective port.  Radio Messages encrypted with Ägier receive predetermined padding letters as 5th filler letter in the initial and final radio identification groups.  This solution can be maintained if the padding letters are changed from time to time. 
  Since wavelengths from the U-boat Circuits sometimes appeared more favorable for transmitting messages between Penang and the objective port than wavelengths from the "Bruno" radio circuit, it must be ensured that Radio Messages encrypted according to Ägier can also be decrypted on U-boat Circuits. See section d). U-Boat wavelengths recognized as favorable for transmitting:
  Ireland "rx" from 19.00 to 21.00 DGZ and America I "cd" from 17.00 to 20.00 hours DGZ.  Traffic on Choshi Radio posed great difficulties (See Section e) and therefore the Command suggests:  because the Naval Attaché Tokyo receive side radio circuit "Bruno" is manned, it only has to be on a particular wavelength of the "Bruno" radio circuit at certain Program Times in order to pick up all the messages transmitted from the boat on these wavelengths, even if the Control Center does not hear them.  If these suggested Program Times are between those of the one-side Tokyo Radio Service, the Naval Attaché Tokyo may very quickly give the boat an acknowledgment of receipt, which is essential.  Traffic via Choshi Radio may remain as an additional way to send Radio Messages.  If a German base in Penang or Shonan receives a transmitter and this also switches to the "Bruno" radio circuit at the suggested Program Times, they can possibly act as a radio repeater.
                     
   
                              Kptlt. and Kmdt.
Ltn.z.S. and Radio Message Officer