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

Fri Mar 8 11:48:08 EST 2024

I remember using 2125 and 2925 Hz on receive and directly FSK of my Viking
Ranger. It IS interesting how stuff has moved around. In the US, anyway,
we stayed with mark on 2125 Hz and shift up 170 Hz instead of 850 for
space. When run through an LSB transmitter, we end up with the space being
on a lower frequency than mark.

I wonder if the reversal on RF to space high was due to the introduction
of SSB transceivers to the military. It seems that many commercial
transceivers (such as my marine SEA245
https://w6iwi.org/SEA245/SEA_245.pdf which is only USB unless put into
amateur mode) may only support USB. To avoid changing tones, the RF low
space MAY have been changed to high space.

Finally, on my DSP TU ( https://w6iwi.org/rtty/DspTU2/ ), I don't call it
a "reverse" switch. Instead, it is labeled "Mark High." When that button
is lit the audio mark tone is above the space mark tone.

In the DSP TU, there is also a "Shift" button that results in 850 Hz shift
when lit. The configuration data holds the center frequency and shift for
each mode. The tone filters are then loaded with the appropriate
frequencies and Q, calculated from the configuration data based on the
setting of "Shift" and "Mark High."

Anyway, I wonder if the RF frequency swap is due to the introduction of
SSB transceivers that only supported USB.

Harold
https://w6iwi.org

On Fri, March 8, 2024 8:59 am, Nick England wrote:
> At least one thing works out when running AFSK. If xmt/rcv audio is mark
> low, you will be OK for military USB (RF mark low) and also OK for ham LSB
> (RF mark high).
>
> Nick England K4NYW
> www.navy-radio.com
>
>
> On Fri, Mar 8, 2024 at 10:43 AM John Spigel <w1an.dxusa at gmail.com> wrote:
>
>> And, for us today, adding to the permutation mix of possible settings
>> you need to include along with AM/FM, USB and LSB.  With some mix of
>> combinations, not necessarily the same, we can talk to each other. The
>> Dovetron Tempest I'm playing with had an AFSK output which initially I
>> set for Mark Low, Space High with normal operation LSB.  But on the net
>> last Saturday I needed to copy in REV, because the other side of the QSO
>> needed to go to REV to copy me and we are on USB! We could copy, but,
>> unless told, what I think are correct settings are not! I could of
>> course flip the Mark and Space with the front M/S frequency dials, but
>> that would add to my confusion.  So in the interim I've added a switch
>> on my Dovetron rear panel to flip High/Low for my loop generated Tx
>> signal to give me that option and let others in the group copy and
>> transmit "Normally" and for me to determine what is NORMAL. I'll
>> probably also need to keep a cheat sheet!
>> 73, John W1AN
>>
>>
>> On 08-Mar-24 13:27, John Vendely wrote:
>> > Hey Nick,
>> >
>> > 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...
>> >
>> > 73,
>> >
>> > John K9WT
>> >
>> > On 3/7/2024 1:16 PM, Nick England wrote:
>> >> From a 1989 Coast Guard Manual -
>> >>
>> >> CV-3883/UG Converter Keyer AFSK Frequency Adjustment Information
>> >> If you have ever aligned a CV-3883/UG Dovetron you probably noticed
>> >> the absence of Navy and Coast Guard frequency shift information. Î¤Î¿
>> >> complicate matters, prior to about 1972 the Navy's Normal mode of
>> >> operation was wide shift RATT with the MARK tone HIGH and the SPACE
>> >> tone LOW.
>> >> The Navy made Reverse keying MARK tone LOW and SPACE tone HIGH the
>> >> normal mode of operation in 1972 but stayed with wide shift. On
>> >> existing signal conversion equipment radio operators would put the
>> >> RATT converter in the REVERSE mode to correct the output logic of the
>> >> received now MARK LOW signals.
>> >> Technical manuals for older Navy equipment reflect the original Mark
>> >> High Space Low convention e.g. the CV-2460/SGC. Manuals for newer
>> >> equipment e.g. the AN/URA-17E reflect the Mark Low convention.
>> >> The Coast Guard uses Space High Mark Low narrow shift keying as its
>> >> normal mode of operation. Some old timers argue that this is REVERSE
>> >> keying, but the bottom line is that Mark Low is the standard to which
>> >> we align our CV-3883/UG in the Normal mode of operation.
>> >>
>> >> ______________________________________________________________
>> >> GreenKeys mailing list
>> >> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
>> >> Help: http://mailman.qth.net/mmfaq.htm
>> >> Post: mailto:GreenKeys at mailman.qth.net
>> >>
>> >>>>> Jordan Spencer Cunningham's GreenKeys Search Tool:
>> >>>>> https://teletype.net/gksearch
>> >>>>> 2002-to-present greenkeys archive:
>> >>>>> http://mailman.qth.net/pipermail/greenkeys/
>> >>>>> 1998-to-2001 greenkeys archive:
>> >>>>> http://mailman.qth.net/archive/greenkeys/greenkeys.html
>> >>>>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
>> >>>>> http://comcents.com/tty/greenkeyssearch.html
>> >> This list hosted by: http://www.qsl.net
>> >> Please help support this email list: http://www.qsl.net/donate.html
>> >> Message delivered to jvendely at cfl.rr.com
>> > ______________________________________________________________
>> > GreenKeys mailing list
>> > Home: http://mailman.qth.net/mailman/listinfo/greenkeys
>> > Help: http://mailman.qth.net/mmfaq.htm
>> > Post: mailto:GreenKeys at mailman.qth.net
>> >
>> >>>> Jordan Spencer Cunningham's GreenKeys Search Tool:
>> >>>> https://teletype.net/gksearch
>> >>>> 2002-to-present greenkeys archive:
>> >>>> http://mailman.qth.net/pipermail/greenkeys/
>> >>>> 1998-to-2001 greenkeys archive:
>> >>>> http://mailman.qth.net/archive/greenkeys/greenkeys.html
>> >>>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
>> >>>> http://comcents.com/tty/greenkeyssearch.html
>> >
>> > This list hosted by: http://www.qsl.net
>> > Please help support this email list: http://www.qsl.net/donate.html
>> > Message delivered to w1an.dxusa at gmail.com
>>
>> ______________________________________________________________
>> GreenKeys mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:GreenKeys at mailman.qth.net
>>
>> >>> Jordan Spencer Cunningham's GreenKeys Search Tool:
>> https://teletype.net/gksearch
>> >>> 2002-to-present greenkeys archive:
>> http://mailman.qth.net/pipermail/greenkeys/
>> >>> 1998-to-2001 greenkeys archive:
>> http://mailman.qth.net/archive/greenkeys/greenkeys.html
>> >>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
>> http://comcents.com/tty/greenkeyssearch.html
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to navy.radio at gmail.com
> ______________________________________________________________
> GreenKeys mailing list
> Home: http://mailman.qth.net/mailman/listinfo/greenkeys
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:GreenKeys at mailman.qth.net
>
>>>> Jordan Spencer Cunningham's GreenKeys Search Tool:
>>>> https://teletype.net/gksearch
>>>> 2002-to-present greenkeys archive:
>>>> http://mailman.qth.net/pipermail/greenkeys/
>>>> 1998-to-2001 greenkeys archive:
>>>> http://mailman.qth.net/archive/greenkeys/greenkeys.html
>>>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
>>>> http://comcents.com/tty/greenkeyssearch.html
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to harold at w6iwi.org

-- 
Not sent from an iPhone.