FW or FA is "negative keying" of the Polish NDB DRE on 440 kHz.

The term "negative keying" describes a strange situation where the Morse code identification of an NDB becomes "inverted". This can produce some strange sounding IDs, and can often be characterized by uneven spacing, or a very long dash, which appears between the callsigns. Many of the ones that are frequently heard are located in Eastern Europe, though negative calls have also been heard from Western European countries from time to time.

"Negative keying" actually results from a drop (reduction) of the NDB transmitter's carrier level (amplitude) during the time when the transmitter is being keyed, i. e. transmitting the NDB's Morse code identification. Hence the most likely spot to find negative keying is to tune directly to the NDB's carrier frequency and operating the receiver in narrow CW mode.

If you want to translate between positive and negative callsigns (or vice versa), you might want to try the following procedure:

- Inside each Morse code character, the short period of silence between two adjacent "dits" or "dahs" or "dit-dahs" or "dah-dits" becomes a "dit".

- A "dah" becomes a character separator.

- The long period of silence (character separator) between two Morse code characters becomes a "dah".

- The very long silence between two consecutive IDs of the NDB becomes a very long dash.

Below I've tried to sketch a little graphical representation for some of the more frequently heard NDBs that are producing negative keying. The vertical line | indicates a character separator. Please have a look at the following examples:

C --------F
- . - .|. . - .
|. .|. - . .|.
--I----L----E

G----R-----U
- - .|. - .|. . -
|.|. - .|. - . .|
E--R-----L

and finally:

D-----R--E
- . .|. - .|.
|. . - .|. - |
----F----A

vy 73 + gd DX,

Michael


RX: ICOM R75, ICOM R71A,
Sony ICF-SW7600G, W&G SPM-3, Präcitronic MV62
Antenna: Radio West 22.5" ferrite loop with amplifier,
20m longwire, Wellbrook ALA 100
Location: Roschbach, Germany N 49°15' E 8°07' / Locator JN49BF
Editor of "The European NDB Handbook" & "The North American NDB Handbook"
cf. http://www.beaconworld.org.uk/datafile.htm

© 2004 RU6LA