[GreenKeys] Military Mark High to Mark Low change - FWIW

Sun Mar 10 12:03:55 EDT 2024

I was reading some old notices on NATOs website (Very interesting all the available orders and rule changes, Just look up RATT and things like that) 

While I can’t find an exact change I wonder if it was just a way to force standardization.  I read some earlier STANAG 5003 notices that specified everyone needed to use 50baud except for the USN (Probably because of the installed base) Then the USN switched to 75 Baud which was still not the NATO standard in 1968 with a caveat that everyone convert to 75 on an agreed upon date.   

This combined with the fact the Mark would be at the top end of the frequency as others have stated in this thread probably forced the issue.  

Either way still not a definitive answer but a lot of interesting reading that spans about 10 years time from 1957-1968 and the changes that happened in NATO communications.  

This link still shows Mark High in 1961

https://archives.nato.int/uploads/r/nato-archives-online/b/6/3/b63f7b729941bdb65957c2c1e9bd7a44f0e006263adcf2486250d075f2a48095/SGM-0223-61_ENG_PDP.pdf
SGM-0223-61_ENG_PDP
PDF Document · 1.1 MB

This one talks about the limits of bandwidth, not really specifying RATT in particular but they do worry about bleed over if I am readying right.

https://archives.nato.int/uploads/r/nato-archives-online/9/f/2/9f2d7c59d12232335b8cea1fcb5ba5991fa6de4a3eb78f9017987eebe100fd66/IMSM-0216-67_ENG_PDP.pdf
IMSM-0216-67_ENG_PDP
PDF Document · 1.4 MB

This one specifies the use of USB only

https://archives.nato.int/uploads/r/nato-archives-online/f/4/d/f4d506d0915455ddae55956910c7c98e661681da693a45d2be710f2ff26e6344/IMSM-0468-68_ENG_PDP.pdf
IMSM-0468-68_ENG_PDP
PDF Document · 4.6 MB

https://archives.nato.int/uploads/r/nato-archives-online/4/4/d/44d13bbd4bd51d7a4067110a8bc797323c72772661314b5ce89f66636baf1802/SGM-0488-63_ENG_PDP.pdf
SGM-0488-63_ENG_PDP
PDF Document · 521 KB

https://archives.nato.int/uploads/r/nato-archives-online/5/5/c/55c2a8aef7bafe4f2f254a0e324f254c5d4e5c35175891bd8fbc57e278a4b053/IMSM-0429-68_ENG_PDP.pdf
IMSM-0429-68_ENG_PDP
PDF Document · 651 KB

Daniel Jones (K6YIC)
DJones at k6yic.com
http://K6YIC.com
HH Phone #11973

> On Mar 8, 2024, at 16:16, Dave Horsfall <dave at horsfall.org> wrote:
> 
> On Fri, 8 Mar 2024, John Vendely wrote:
> 
>> The reason for various military branches switching from MARK high to 
>> MARK low is surely one of the world's great mysteries, on par with the 
>> construction of the pyramids.  From an engineering perspective, the 
>> choice is entirely arbitrary, but so far as I can see, prior to the U.S. 
>> Army's introduction of the MD-522 in 1967, MARK high was the 
>> convention.  So why change?  This must have been a bit confusing at 
>> times for Army RATT operators, since their existing GRC-26 and GRC-46 
>> equipment was MARK high...
> 
> Perhaps it may have something to do with higher frequencies being 
> attenuated or something?
> 
> -- Dave (vk2kfu)______________________________________________________________
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