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Re: LF: MW

To: [email protected]
Subject: Re: LF: MW
From: jannsen <[email protected]>
Date: Mon, 20 Dec 2004 19:24:35 +0100
References: <[email protected]> <[email protected]> <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
Michael Oexner schrieb:
Hi Uwe, Walter & list:

I'm attaching a list with NDBs that are listed on 440 kHz +/- 2 kHz.

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,

Hi Michael,
thanks for the efforts you made explaining us the effect of negative keying.
best regards

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