LF: Re: ROS s/ware

["James Moritz" <james.moritz@btopenworld.com>]

Dear Dave, LF Group,

>Their first suggested working frequency on 20m put it splattering
> right over the IARU beacons on 14100, which it seems the developers had
> never heard of.
"Splatter" usually refers to distortion products outside the signal 
bandwidth of a signal, but these don't really occur with ROS and other 
constant-amplitude, FSK,  modes since there is only a single tone being 
transmitted at any one time, and so nothing else to intermodulate with, even 
if the TX is highly non-linear. So this complaint is technically 
nonsensical, although 14.1MHz obviously isn't a good choice of frequency! 
What people seem to get excited about is that the transmission has a 
bandwidth of 500Hz, or 2.2kHz - somewhat wider than some other modes, with 
the objective of trading off increased bandwidth against achieving increased 
robustness. The theory is fine; finding out if this actually works and 
offers any practical advantages is why we should be trying it out of course. 
The 500Hz bandwidth easily fits into the "digital" segment even of 500kHz, 
so no problem there.
BTW, now getting about 95% copy of G4WGT/ 100% of G0NBD having a QSO in ROS 
500Hz / 16baud mode - the bandwidth and centre frequency is as advertised - 
see attachment. Might try transmitting later, but have some other problems 
to sort out first...
Cheers, Jim Moritz
73 de M0BMU

Ros_QSO.jpg
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