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Reply from R .
MF1 ROS is
0.837053 symbols/second. If you can decode at -33dB
(presumably in the reference bandwidth of 2.5kHz) that's +1.7 dB
S/N in a symbol bandwidth, that in the case of 16FSK with
Viterbi Decoder is possible.
ROS calculate
S/N for 100Hz, after tx , show's S/N for an equivalent system of
2500Hz >> CANCEL> -36 dB
<< (end of rx text string)
Sent: Friday, July 02, 2010 8:01 AM
Subject: Re: LF: 137.500 kHz ROS MF-1 beacon
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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