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Re: LF: 137.500 kHz ROS MF-1 beacon

from [Andy Talbot] [Permanent Link][Original]
To: [email protected]
Subject: Re: LF: 137.500 kHz ROS MF-1 beacon
From: Andy Talbot <[email protected]>
Date: Fri, 2 Jul 2010 08:01:55 +0100
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A thought. 
MF1 ROS is one symbol per second isn't it.  If you can decode at -33dB (presumably in the reference bandwidth of 2.5kHz)  that's -1dB S/N in a symbol bandwidth.   Which I'm not sure I can believe.   FSK with good Feed Solomon, or whatever, FEC  needs 2 - 3dB S/N.
 
Is the S/N calculation being a bit optimistic?  The calculation in WSJT / WSPR gives an artificially high S/N value if the input bandwidth is restricted below a complete 2.5kHz's worth, and if impulsive noise is present.  So could ROS be suffering some similar effect?
On 1 July 2010 23:47, Graham <[email protected]> wrote:
 
Gary,
 
Just a  couple of db's   short  of a  decode  via the  web , -36 is going some though
 

RX1:

21:55 @ 13.8 Hz: *[:]V-KFY:32DM5#("")EM3H#/F[_ <CANCEL> -36 dB

G ..

 

Sent: Thursday, July 01, 2010 6:35 PM
Subject: LF: 137.500 kHz ROS MF-1 beacon

Hi LF,

My ROS MF-1 beacon is transmitting now with 3 minute timer.

Frequency is 137.500 kHz (dial 136.500 kHz USB), reports & QSO attempts very welcome.

ERP about 50mW.

73

Gary - G4WGT - IO83QO



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