Andy,
I guess it is the same SNR issue that has been noticed with WSPR.
As you mentioned SNR is calculated for SSB bandwidth. If some uses a narrow filter the calculated SNR is too low.
If I remember well one of our French friends used a very narrow filter for 500kHz WSPR reception, resulting in solid copy at very low (calculated) SNR levels.
73, Rik ON7YD - OR7T
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
