quick brown fox jumps over the lazy dog
dl4yhf
...-.-
cq cq ddl4yhfd4yh e k
F4DTL Nicolas
Ok, I was inspired for that sentence when
reading the WSQ help pages :-)
btw Murray ZL1BPU has answered my questions regarding notch filter,
guess he won't mind relaying his entire message here.
Note the last sentence.
Cheers,
Wolf.
-----
Wolf,
I can read the rsgb_lf_group reflector, but not post to it
(problem getting them to change my login). I am pleased to note
your interest in WSQ2. I can hopefully answer your questions about
it works.
First, there is no notch filter, so if there are interfering
carriers, you’ll need to QSY. Not ideal, I know, but with no error
correction with a puncturing function there would still be no way
to recover from all the errors. The source code is available, so
if you want to try, you could add a notch filter.
The important reason behind not using FEC is TYPING SPEED. We
designed it for 5WPM. WSQ2 is intended to be a QSO mode, like CW.
If there are errors, you ask for repeats. In our experience (we
also tested WSQ with FEC), for the same text speed, there is
little difference between reception quality of 0.5 baud with no
FEC, and 0.25 baud with standard NASA convolutional coding FEC.
The big difference was that the FEC version was of course much
slower. Yes, the FEC version had slightly fewer errors at around
–24dB SNR, but it dropped out at –25 just like the non-FEC
version.
Exactly the same situation applies when you compare DominoEX4
with THOR8. Similar sensitivity, but double the speed. It’s all
about the integration time – the slower symbol rate has an impulse
noise rejection advantage as well as a sensitivity advantage.
You have to realize that WSQ2 is designed as a real-time QSO
mode, it is not for beaconing or propagation measurement. Sure,
you need slightly more signal than for WSPR, but you can have a
real QSO with a real person. FEC, and especially block modes,
don’t lend themselves to this level of operating freedom.
If anyone on the rsgb reflector has any questions about the
mode, please point them in my direction.
73,
Murray ZL1BPU
