ITU HF (and VHF) Kurier System 2014
(based on Kurier System; c.1942-1945)
Historical Origins of the Kurier System |
In August 1944 the Kriegsmarine (German Navy) began testing an experimental system called "Kurier", designed as a counter-measure against the High Frequency Direction Finding (HFDF). The transmission system was based on a principle now known as burst-encoding. The principal 3 component Kurier System sending device was connected to a radio transmitter in the work area of the Radio Officer on a U-Boat or weather boat. The system was never experimented with for use with battleships or cruisers.
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Together with start pulses and pauses
between letters, the complete transmission of the short message took
never more than 460 milliseconds (under 500ms)! In an era (1940s, 1950s) where it could take up to 2 minutes (ideally 45 seconds for continuously monitored frequencies) per HFDF fix (within ~2 degrees of accuracy), the Kurier System would have been of great tactical advantage. Yet, the Kurier System was barely used. |
NOTE The U-Boat Kurzsignal (originally designed for Morse Code use, but adapted to the Kurier System) had to be physically converted into Morse Code bar settings at the sending unit. This was the only design overhead of the Kurier System. The Kurier System could not send long signals (say of 25 Morse symbols, 5 groups of 5 letters). The lack of ability to send long signals was a huge system design defect. |
SIGNAL DESIGN PARAMETERS Preamble
Signalling
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Modern Implications of Kurier System Signal Interception Capabilities |
Modern Wullenweber arrays (for which there are remarkably few
still existent since the end of the Cold War) can [in array mode] do
an HFDF fix to within (+/-) 0.25 degrees under normal conditions for
signals lasting 50ms. Wullenweber arrays take a lot of staff to maintain optimal functionality (in spite of the systems being in their 7th to 9th generation of modernization). SETI @ Home type signal extraction and decoding for transcription for Wullenweber systems are probably as old as SETI @ Home, with one multicore computer (in a cluster of computers) per 200khz. Wullenweber Arrays, how many does one need for HFDF?
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To what extent Wullenweber systems
actually monitor the HF bands for burst transmissions is unclear,
but probably all traditional RTTY signals can be extracted at
Wullenweber SIGINT locations. The NATO and Echelon HFDF monitoring
systems are not what they once were during the Cold War, and
although the monitoring systems like this may be fully automated
their ability to pick up burst signals is unclear. Wullenweber systems may somewhat discourage security intelligence people from using a Modern Kurier System for transmitting messages, but for the spy crowd things are technologically better. Globally -- the security intelligence agencies have access to far more illusive and evasive coding and transmitting technologies. Wullenweber systems are an IT issue to be dealt with, not an overpowering technical or technological problem. |
No
legal issues for Amateur Radio
For Amateur Radio use in the Amateur Radio bands, there is no reason to worry about using the Kurier System legally or otherwise. This Modern Kurier specificaiton is not at all like the original 1942 version, but it has many design commonalities with it. ITU Legal Rules for Amateur Radio Notice As long as a modulated signal (and or encoding format) is publicly specified in an easily accessible forma
This ITU rule was designed to allow Amateur Radio experimentation in encoding and modulating systems, as well as normal operations. This ITU rule allows Amateur Radio operation to be possible accross borders (and inside nation states) while avoiding conflict with any domestic security regime or trans-national secruriy regime (like NATO). |
Mode | Preamble Pulse | Preamble A | Preamble B | Preamble (A|B) | Message 0 | Message 1 | Inter-letter | Inter-word |
Duration | {PRE A} | {PRE B} | Spacer {PRS} | Dot "_P_" | Dash "_P_P_" | Spacer # x "_" | Spacer # x "_" | |
equals # x "_" |
Duration |
Duration |
aka 'Marker' |
|||||
into Message {PRS.m} |
0 ▷ 0 : 3TC | 1 ▷ 0 : 2TC | ||||||
0 ▷ 1 : 2TC | 1 ▷ 1 : 3TC | |||||||
Morse |
3TC, "P__" | 40 Pulses | Not Applicable | 31TC |
3TC | 5TC |
5TC |
9TC |
-- Dotty |
6TC |
97 Pulses |
19 Pulses |
37TC |
3TC |
5TC |
5TC |
7TC |
-- Dashey | 6TC, "P_____" | 97 Pulses | 29 Pulses | 41TC | 3TC | 5TC | 5TC | 7TC |
RTTY6 |
2TC, "P_" | 67 Pulses | 67 Pulses | 67TC, into Message 61 |
3TC | 5TC |
3TC |
Not Applicable (0) |
RTTY7 |
2TC | 77 Pulses | 77 Pulses | 53TC, into Message 59 |
3TC | 5TC |
3TC |
Not Applicable (0) |
RTTY7P | 2TC | 77 Pulses | 88 Pulses | 43TC, into Message 53 | 3TC | 5TC | 3TC | Not Applicable (0) |
RTTY8 | 2TC | 88 Pulses | 77 Pulses | 41TC, into Message 47 | 3TC | 5TC | 3TC | Not Applicable (0) |
RTTY11 | 2TC | 33 Pulses | 44 Pulses | 23TC, into message 41 | 3TC | 5TC | 3TC | Not Applicable (0) |
Notes
Syntax
Encoding
Message Integrity
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Message Syntax |
This specification does not handle the cryptographic encoding of
message content in any way. It is up to user to encode binary files
or Morse Messages in any code or cipher they may wish. Cryptographic encoding may be necessaery to guarentee message or binary file integrity. Open message cryptographical encoding (where the key and code used are in plaintext) is recommended for Amateur Radio use. Dotty or Dashy Morse Code encodings are not cryptography, as they are technically "Prosigned" Morse. |
Formal Transmission Syntax
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Morse Code {PRE A}{PRS}{MMM}{KK} Morse Code (Dotty or Dashy) {PRE A}{PRS}{PRE B}{PRS.m}{MMM}{KK} |
RTTY (with no error correction) {PRE A}{PRS}{PRE B}{PRS.m}{MMM}{KK}{KK} RTTY (with error correction) {PRE A}{PRS}{PRE B}{PRS}{PRE B}{PRS.m}{MMM}{KK} + [{KK.256} | {KK.5} | {KK.mpeg}] |
Burst Communications
Morse
RTTY
Error Correction
Created By | Initial Idea | Created | Current Version | Version | Last Change | Revision State | ||||||||
Max Power | 10 July 2014 | 25 August 2014 | 15 September 2014 | 0.76a | Appearance |
Revisable, Updatable |