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5 letter groups

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aggie72

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#9
Those are "cut numbers" : abbreviated morse code instead of sending long number. "AANWA" is 11931. Have you tried listening there after signoff/QSY?
Morse Code Operating Aids
I'm not familiar with "cut numbers" or MAFOR. Here is a sampling of the broadcast if any one cares to venture a guess:
RRGAT NAANU WANDT DGDNA AIRTD IUADG AGGRT GDAWU NGUDN TAUNI UNUTR TUAGN GNWAU WTTNA INARA INIUD DWNGG RDUTN NTNUW UINRD NWAAT WUNWW UGWDW GUTGT AWNNU RAAGW GDAIT AUTIU RDDWG GAWNG DRRNR RWIIU TGTII TRIDW WGNTW GRWUT WWIIW TTNAG
IWTGR WWRIG GTTWU RUNRW RATTR NIGRA NIGID NTIIT RRNNA GAURG DINAD DDNTT IUAID IWAAW TDDGU TLUIN RAAAI AURNN AGDWD ITRGI IUAAN UWUNA IAUGU GURUA ININA TDTUA ATTRA INGDI UUADD AIUWN IIRRW AIUAN IRNUG TTWNI IGRUW IUIAR GWGGU NDIGR
 

Token

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#10
The station heard was almost certainly Cuban MCW numbers station M08a. They have a regular schedule on 5800 kHz at 0600 UTC.

Cut numbers are a shorthand method of using short CW letters in place of long CW numbers. In the case of M08a they use the letters ANDUWRIGMT to replace the numbers 1, 2, 3, 4, 5, 6, 7, 8, 9, 0. A=1, N=2, D=3, etc.

OK, you may notice I said this was M08a and they have a schedule on 5800 kHz, but you reported 5801 kHz. Neither of us are in error.

M08a most often uses MCW. This is a full DSB plus carrier AM transmission. They modulate a 1 kHz tone on the carrier. If you tune to 5800 in the AM mode you will hear CW with a 1 kHz tone. If you tune to this signal in the CW mode of your receiver, but tune to 5801 kHz (the center frequency of the CW characters) then you will hear the CW with whatever pitch offset your radio uses for CW, frequently between 600 and 800 Hz. By the same token you could tune 1 kHz below the carrier, at 5799 kHz, and hear the same signal.

M08a sometimes uses what look like a normal ICW (keyed CW, what most hobbyist refer to as “CW”) signal. When they do this they are most frequently 1 kHz under their scheduled freq. This is because they use the same 1 kHz audio tone as when they are in MCW, but the transmitter is in LSB mode, creating what looks like keyed CW 1 kHz under the scheduled freq. Very, very, occasionally they make a mistake and do the same thing in USB, resulting in keyed CW 1 kHz high.

Anyway, the next time you see or hear this station flip over to AM and see if the CW is still copyable. This will indicate they are in MCW/AM mode.

T!
 

aggie72

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#11
I think that explains it pretty well. At the end of the broadcast I did briefly go into AM mode and did hear the 1 Khz tone so you are right about that.

Thanks,
 

Token

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#12
Here is a video of this transmission (at least the same frequency and time slot, I was not recording it specifically on the day you reported).

Numbers Station, Cuban, M08a MCW, November 10, 2012, 0600 UTC, 5800 kHz AM (MCW) Mode - YouTube

Note that in this video I start out with the receiver in CW mode and tuned to 5801 kHz. I then shift to CW and 5799 kHz, then to AM on 5800 kHz, and later USB and LSB are also used, tuned to 5800 kHz, and I do the majority of the video in AM mode and tuned to 5800 kHz. The purpose of this is to show how many modes can be used to "correctly" receive a signal sent in MCW.

T!
 
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#13
She was on again last night 11th November, S7-9 here at 0600UTC on 5800kHz MCW sending cut numbers - funnily enough in the usual sequence of G's and W's there the occasional "R", wonder what that means??? Then she sent "TRIGA" many times at 0614 then back into the numbers again....

Kenwood R2000 from 66ft wire strung N-S about 20ft up via a 9:1 impedance transformer.
 

Token

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#14
She was on again last night 11th November, S7-9 here at 0600UTC on 5800kHz MCW sending cut numbers - funnily enough in the usual sequence of G's and W's there the occasional "R", wonder what that means??? Then she sent "TRIGA" many times at 0614 then back into the numbers again....

Kenwood R2000 from 66ft wire strung N-S about 20ft up via a 9:1 impedance transformer.
R is the number 6 in cut numbers. G is 8 and W is 5. There is no "usual" sequence of G's and W's, the transmissions are determined by who the message is intended for and what the message body contains. The first several minutes of transmission is the recipients (all 3) for that time blocks transmission, repeated over and over.

The station (assuming M08a format) sends three message bodies in slightly over 45 minutes, each with 150 groups. Each message goes to a different recipient. The break at 0614 was the end of the first 150 groups and the start of the next 150 groups. The "TRIGA" that was sent over and over is "06781" and it is the recipient of the 2nd set message body, in this case. If you had listened closely you should have heard another break at about 0630 or so and a single 5 figure group sent repeatedly, and this is the recipient ID for the 3rd and final message body.

T!
 
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#15
There is no "usual" sequence of G's and W's,
Oh yes, I realise that! It was just for example :wink:

Perhaps I haven't taken enough interest to interpret "R" as "6", but haven't I heard other stations using a different code - AUVHENDBMO? I seem to remember that a Shell Tanker I was R/O on had a 5 number code something like that, although it was nearly 50 years ago...
 
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